Smart Pioneers

The making of a Classic Portland Snowstorm.

Just a short post about the weather because its the middle of winter and we just experienced a classic Portland winter situation. It wasn’t major or destructive but it was a classic set up that a gardener should be aware of in the future because it has happened innumerable times in the past and it will happen in the future. I’ll try to explain it in a way that is easy to understand and show some of the things to look for and how a classic Portland snow/ice storm sets up.

The Jet Stream and damn cold

We had a remarkably active jet stream throughout the month of December. It landed us with a record amount of rain for the month and aside from sodden hillsides and swollen rivers it pretty much soaked our gardens. For several weeks warm, then progressively colder storms streamed in, soaked us and then repeated. So it was not a surprise at all when the jet stream not only backed off it split. VERY El Nino. In fact, research shows that the strongest El Ninos produce some pretty prodigious rains for the PNW before turning the Jet Stream to the south. In the last week of December what is known as a REX block stopped storms from impinging on our region. High pressure- thats air that is sinking and drying- in a clockwise motion stopped the storms and with a slight northeast bent it ushered in very cold, (not quite arctic) dry air east of the Cascades. The jet stream dropped to our south into Northern California.

ICE STORMWintery Scene



A Bora Wind

Cold high pressure enveloped the Columbia Basin where dense dry and almost arctic air collected. The Columbia River Gorge is a sea level path through the mountains. As low pressure centers rode the jet stream into N. California it set up a dynamic sucking the cold dry air through the Gorge. So- there was low pressure to the south west and high pressure to the north east. The perfect set up for an easterly flow. Air flows from high to low pressure and in this configuration its sent blasting through the gorge.  A Bora wind. This steep pressure gradient was responsible for the wind that lashed Portland for several days at the end of December and beginning of the New Year. A pressure gradient can be likened to a ball rolling down a slope. The steeper the slope (closer the bars of pressure are aligned ) the faster the ball rolls and the steeper the gradient the faster the air goes. Confined to the slim width of the Gorge and you have yourself some wind. On top of this the Columbia Basin and eastern Oregon, the source of our cold air was refrigerating in a large and expansive low elevation snow pack. Cold. As you were aware  that frigid air moved into the Portland area and down the Valley. It even blasted out of the east facing canyons at the beach.

Dewpoint, down, down, down

Two things to watch when an east wind (Bora) wind sets up are the temperatures at the source of the wind and then the dew point. Cold air is dry air- the colder it is the less moisture air can hold. (The molecules are closer together). Without going into graphic detail, lets just say that you should be aware of the dew point in Troutdale because they are at the front doorway of cold dry conditions. I watched the dew point dip day after day through the twenties and down into the teens. Tell tale signs of not only the measure of the atmosphere but the depth of cold air at the surface. Typically several days into an east wind event the temperatures at Troutdale will not plunge- but the mixing of the air will keep the temperature up. The dew point however, is where to look, it edges steadily lower. The other important clue is the temperatures east of the Cascades. If it is in the teens or single digits in Pendleton and the teens or colder in The Dalles- thats where our air originates and pressure gradients are shipping it to us directly. Those conditions were present.

A (weak) moisture source

What happened on January 2nd was  a classic set up for snow and then freezing rain in Western Oregon. The cold, dry air that had been flooding the western part of the state became entrenched at the surface. Remember, cold air is dense and it follows the contours of the ground- it sticks close to the surface it fills up the valleys and canyons. Slowly, the rex block high pressure that had capped our atmosphere gave way to lower pressure edging north from California. Moisture rode northward and over topped the cold air. I should say that if a storm is strong and comes barreling in it will scour out the cold air at the surface and there is a faster transition. This time, the weakness of the system moving north left the air in place and after days of easterly flow cold air was deep. The first precipitation to fall into that air mass began as snow and ended in freezing rain. The large difference between the air temperature and the dew point (humidity) shows the large depth of cold air. And hence we got about 1.5″ to 2.5″ of fluffy snow in the morning of the 3rd. More was to come.


Grevillea australis all iced up.

A Silver Thaw

This is a term I learned as a child and its fallen out of modern favor instead replaced by more scientific lingo. Yes, we are all becoming junior meteorologists, but from the past I bring up ‘Silver Thaw’ because it was well known to our predecessors and it is so aptly descriptive. Freezing rain occurs when the layer of cold air over us is eroded and over topped by warmer air and moisture. Precipitation begins as snow, falls into warm air and melts and then if the layer of cold air at the surface is deep it refreezes. Technically, this is sleet – its the ice balls that bounce and pelt you. As the warm air becomes deeper (eroding the cold surface air) rain does not refreeze, instead it remains liquid but becomes super cooled and it will freeze on contact with every surface- the temperature is below freezing but rain is falling. Glazing, is the term but I prefer ‘Silver Thaw’- harkening back to true Oregonian roots. Typically, in this set up the East Wind continues to pour cold air into the western valleys and is met by more moisture over riding from the west and south. We were lucky this time that the storm was not particularly wet. Hence, we had only about .25″ of ice and we escaped real tree damage and a prolonged bout. Warm air then wins out- the perfectly applicable term ‘Silver Thaw’. The Pioneers knew what they were talking about.

That may be it for winter

I probably don’t need to point out that the window for truly arctic air to come into our gardens is waning quickly. Typically the final gasp of that kind of air dies around Valentines Day. It can get cold after that and certainly freeze but true arctic air is extremely rare and as far as I am concerned that is spring. So long term forecasts are not showing any real set up for arctic air. We could be out of the woods. I’ll continue to watch it closely and chime in if I see anything that looks dangerous. Until then, we are probably looking at the second zone 9 winter in a row. YAY.


Smart Pioneers

Cold damage details

Its now time to get up and personal with your garden to begin to really see what specific damage our winter has wrought. This is my third and final post on the winter of 2016/17.   Greg and I have been obsessively observing cold damage now for almost 20 years as growers. I’m going to give you some tips that we’ve learned as well as a plant by plant analysis of some genera. Growing a garden is a crap shoot and if one thing doesn’t go right something else goes wrong as we say and as Greg is always telling me. “They are plants after all”. My previous post ‘Whats in a zone’ shed light on how cold affects plants. This post will be much more specific.

It could have been worse

I’ve seen much much worse freezes. In February 1989 when I was in college a massive arctic outbreak tore down from Alaska. Following weeks in the 50s and even 60s plum trees were in full bloom and spring was in full gear. The high temperature was 61ºF on Monday and by Thursday it was just 14ºF (for a high (!) and the low was 0ºF. The damage was immense- even rhododendrons and cherry laurel (Prunus laurocerasus) froze to the ground or died outright.  All roses were toast and those plums in bloom lost most of their major limbs.  Our worst freezes are when mild weather precedes arctic air and with our wet conditions plants are flush with water and haven’t entered dormancy and they are shocked by dry cold conditions. This year believe it or not we were relatively lucky. The warmest November ever was followed by a December that had 17 days below freezing but no real arctic air. This hardened plants to the more severe cold of January. If we had gone into December from November with the deep cold we had in the middle of winter it would have been so much worse.

The three stages of damage

So, the first stage of damage  occurs when we still are experiencing arctic conditions (lows below 20ºF). For instance, Abutilons will look fried immediately at temperatures in the teens. Zone 9 plants in general will die or look awful. The second stage of damage occurs about 2 weeks after arctic air has abated. That is when you see plants begin to go downhill. Browning, splitting stems, loss of leaves and frozen tips become evident. And remember that our temperatures don’t zoom back up- we gradually warm to the 40’s and 50’s and its often wet. Perfect conditions for Botrytis- rot. I’ll address that in a minute. The final stage occurs in spring with the first really warm days (above 70ºF) and plants break dormancy in earnest  and burst cells and bark split interrupts the plants ability to fully function. Whole branches die or the plant may die to the ground or die all at once. Often a plant that I’m testing for hardiness will look relatively unscathed until this first warm day. Then WHAM! Dead as a doornail- the whole thing just fails.

Take a closer look

There are some things I’d like to pass along. Not all plants respond with cold damage in the same way. Some plants its the tips- the newest foliage that goes. Cistus, Roses, many common broad leaved evergreens.  Other plants its the oldest foliage that succumbs- which can be counter intuitive. As an example,  Callistemons (Bottlebrush) show cold damage in two ways. The oldest foliage will begin to turn brown not the newest. Real trouble occurs when there is bark split. Thats when the woody cells rupture. The split shows up conspicuously if you take a real close look on the stems and trunks. The good news is they can actually recover from some bark split. So don’t give them up for dead. If the split actually girdles (surrounds) the whole stem then recovery is unlikely. In severe cases if all the top growth has failed Callistemons can be cut to the ground and a strong, woody root system will aid in fast regeneration. You will likely lose a year of flowers but you’d be shocked at how fast they can regain their former stature. Make sure they are well watered and maybe add some a compost mulch to speed recovery.



Many Ceanothus definitely didn’t appreciate our cold wet winter

Several other shrubs and trees that show (partial damage) on old foliage:

Arctostaphylos, Callistemon, Eucalyptus, Leptospermum, Agaves, Olearia, Ozothamnus, Evergreen Oaks- just a small list.

Arctostaphylos if it is cold damaged will represent with dead interior foliage while newer leaves can be unscathed. The best way to deal with this is to wait for the dead foliage to become a little dry. Then shake the whole shrub to dislodge the dead leaves. This will leave you with bare twigs which you can then remove. Remember that Manzanitas do not have dormant buds on bare stems and will not spontaneously sprout. If your Arctostaphylos is a species that forms a burl at the base (a swollen woody dome shaped trunk) you can cut the whole thing to the ground for radical regenerative pruning and dormant buds on the burl will erupt and the shrub will quickly regrow.

Rot: The final insult

Following a freeze our temperate climate that is wet is ideal for botrytis or gray rot. Its a fairly obvious mold that colonizes dead foliage and stems. There have been experiments with fungicides applied before and after freezes to combat this. To be honest we don’t use them and I don’t encourage you to- nasty chemicals mostly. There are some more benign homespun recipes for fungicides involving baking soda, toothpaste, butterfly wings and god knows what else.  Well, they don’t work.  The best prevention for botrytis is tidiness. To prevent it from infecting undamaged tissue and spreading ASAP remove dead leaves and branches. For Agaves, this is especially important. Don’t allow dead material to collect in the rosettes (deciduous leaves from other plants)- this can be the catalyst for rot that on already challenged plant tissue and once necrotic tissue begins to spread there really isn’t much you can do. Tenting plants to allow them to dry is one possibility just as long as you can maintain good air circulation. This year Agaves had a triple whammy from the the three things they despise in our climate. Freezing rain and then prolonged cold, and copious rain.  It seems only the most well established and adapted varieties came through all right. So, get out the rake and the pruners and sweep up dead material. Cut out dead branches cleanly and do not let them remain and fester rot. Tidy, tidy, tidy will increase air circulation which will deter mold  and be sure to dispose of dead material.

Agave ovatifolia

Total rejuvenation:

If a plant has frozen completely to the ground there are several things you can do to encourage recovery. First, keep them well watered all summer and add a nice mulch of compost and perhaps a little handful of organic fertilizer to give them a boost. Remember that the more established a semi-tender plant is then the larger the root system from which it can re-emerge. Plants that respond to this treatment are Melianthus, Abutilons (the hardier ones like A. megapotanmicum) Fuchsias, Phormiums, and just about any zone 8 perennial that may have lost above ground growth. A little extra care the following summer yields great rewards and you’ll be surprised, I guarantee, at the rate of recovery.

Spring is here

Spring is here, we’d love to see you at the shop. Greg and I are going to host a little symposium on plant damage so that gardeners can share information on what was a historically obnoxious winter. We’ll be announcing that via our Facebook page.


Cold damage details

Whats in a zone?

Winter 2016/17 will go down as a harsh winter. The combination of prolonged subfreezing weather with multiple bouts of snow and freezing rain exacted a price on our gardens.  I write the tags for Xera and aside from witty repartee I also am tasked with assigning cold hardiness for each plant.  Let me tell you that it isn’t as easy as picking a number out of a hat. Years of observation from both myself and Greg have gone into how I give each plant a rating. Just so you know I make our ratings relevant to our specific climate. I’ll get into that as well as the many other factors that fall into line. And I will tell you that I am far from correct. The capriciousness of weather and climate and microclimates is vast. And I swear that once I have assigned a cold hardiness number I will invariably be proven wrong. Visiting a garden and voila! what I thought was completely tender is there thriving in uninhibited replete glory. I like when that happens. This years weather was NOT funny for avid gardeners in our region. It was a prime example of the most extreme conditions that tests plants. Every freeze is different and I learn something new each time. I work to pass that on to gardeners because above all else I want gardeners to succeed with our plants.

Averages miss the details

Its important to possess a working knowledge of weather to pair with growing plants. This is obvious. We are all familiar with USDA climate zones and most gardeners will tell you what zone in which they reside. Well, it isn’t that simple. Temperatures are compiled at official reporting stations over a 30 year period and averaged to achieve a temperature and then assigned a rating. The last period of record used to assign our USDA hardiness rating was 1980 to 2010. During those years our average annual low was 19.3ºF- USDA zone 8b (15º to 20ºF) at the Portland Airport.  This isn’t up for discussion. In fact, all over western Oregon and Washington we are in zone 8. You may say well in my garden its zone 7 or even zone 6. Nope, the law of averages and reality is against you. That doesn’t mean we don’t experience the kind of cold that can relate to those numbers its just that an annual average is not very helpful for long lived plants.  Remember that averages are made up of extremes which can’t be ignored in a garden and such things as microclimates, soil conditions, and the age and health of a plant all have an effect on hardiness. Most of all simple temperatures miss the all important nuance of the actual weather and how it acts on our gardens.

Hardiness for the long haul

There is another way of looking at the climate with real impacts on our plants- that is expected extremes over time. For instance,  we average 6 years in ten with zone 9 winters. (ultimate lows above 20ºF) and four winters that are zone 8 (10º to 20ºF). That is for the Portland Airport and its a better way of interpreting hardiness. As it turns out we have dropped below 20ºF every four years for the last 18- the same interval between each arctic air intrusion. We have become used to mild intervals and are shocked when a colder than that winter comes a long. (What we locally call Phormium killers).   For a better predictor of plant performance I consider that equation and the even more specific number of the coldest temperature we have experienced in the last 10 years. In Portland that is 11ºF- Zone 8a. Locations in the city are subject to the urban heat island. Concrete, glass, and asphalt retain heat and release it giving the city a warm cushion. In outlying areas it is considerably colder and those areas have a different cold profile and average. For instance, Hillsboro sees an average of three zone 7 winters in a 10 year period and their lowest  1o year temperature is 3ºF (zone 7a). Though the averages puts them squarely in zone 8 significantly colder conditions occur regularly. This must be factored into plant performance. Even more specific are the highs that occur during arctic episodes. Many plants can endure very cold overnight lows but highs above freezing gives them a period of recovery. During our arctic episodes we see subfreezing high temperatures. This continuous stretch of subfreezing weather causes more damage. This year was a prime example of that. So, I factor that into a plants hardiness rating as well.  For instance, many Australian plants can endure very cold overnight lows but they almost always rise above freezing there during the day. This is why you see such plants as Acacia pravissima rated zone 7 but it fails to live through our quad annual freezes- it dies during the day with no daily period of recovery- hours on end below freezing.


The &$#%$%% East Wind

Another way plants can be damaged is by the subfreezing desiccating effects of wind. Our arctic blasts are invariably accompanied by howling east winds from the Gorge. Couple that with insanely low humidity (dew points) and you get a recipe for freeze dried plants. Wind, which can actually keep things milder by stirring the atmosphere is horrible  for plants when temperatures are below freezing. Wind evacuates transpiring moisture from leaves, and lowers the point of freezing, frozen soil prevents the capillary action of moisture replacement- semi tender plants, evergreens and even perennials suffer. Be wary of temperatures below 28ºF and winds above 25mph. (If you don’t own an anemometer use the tried and true Beaufort Method of observed effects: 25+mph winds move the largest branches of trees, cause overhead electrical wires to whistle, and fully extend flags- often with some raucous snapping). The longer subfreezing wind persists the more damage will occur. The closer to the Gorge or the higher in local elevation gives you more wind. In my years of observation conditions such as this can erase fully 10ºF of hardiness from a plant- a whole zone.  That means the temperature may dip no lower than 26ºF (zone 9b) but the effects of wind produce the amount of damage you would expect at 16ºF (Zone 8b) in a calm environment. And this effect is perhaps the most confusing to gardeners and the reason why people come up with crazy zone ratings for their own patch of land, they have observed damage equivalent to that rating. Another example,  18ºF and roaring wind can fry even zone 7 plants. If a plant is particularly susceptible to subfreezing wind I factor that in too.

Plant protection. Is it worth it?

In a complicated way it can be worth it. In the Portland area when you protect a plant you are shielding it from the wind. Wrapping plants doesn’t keep them warmer. It just makes them freeze more slowly. Plants are not warm blooded- they make due with adaptation and we can slow the process of freezing. If you really want to protect a plant place a wind proof screen around it and add an emergency light that projects real heat. I get a kick out of strings of new cool LED lights wrapped around palm trunks…the effect is not protection its more Las Vegas if anything. Even the huge old dangerous glass lights from childhood only heat a tiny amount of space around each bulb- and can cause damage to plant tissue. You are better off providing an actual heat source to raise the ambient temperature. Wrapping containers is another way to make the gardener feel better but only prolongs the inevitable. Clear bubble wrap can act like a mini-greenhouse and provide some daytime warmth but you are better off moving the whole plant to a protected location. Even an unheated garage can make a huge difference.  At Xera we cover all plants INSIDE the hoop houses with clear plastic. This prevents the loss of heat from the ground, provides an added layer of protection and if our arctic air comes with sunshine gives a little bit of daytime heating. The plants may still freeze in their pots but that is slowed as well as thawing is slowed providing a smoother transition and the ability to recover during the day.  Remember that plants in pots are MUCH more at risk because cold air surrounding the container will quickly and thoroughly freeze the soil and the roots. For potted plants that you do not intend to move make sure they are hardy to at least one zone lower than we expect. Zone 7a or lower. Even then the roots on plants vary greatly by species in their tolerance for freezing. And the longer the freeze the more thoroughly frozen the roots will be.


A perfect world

For a plant to achieve maximum hardiness to cold several things must be right. First, the plant should be grown in the most optimum conditions that suit it. That means a borderline hardy plant (Zone 8b) should be sited with protection. That could be the top of a south facing slope, under the partial overhead protection of trees or on a heat accumulating south or west facing wall. Age plays into hardiness in a big way. A good example is Olives (Olea europea ). When young they are significantly less hardy to cold than when established with at least a year or two of life in the ground. The difference is remarkable. Small specimens can barely recover from lows of 20ºF while big trees handle temperatures down to 5ºF with little damage. Most plants exhibit this characteristic. So the bigger the better. Another complication in our climate is saturated soils. Good drainage is key to so many plants – I feel like a broken record writing this on tags but for many plants its key to surviving arctic spells when soil moisture turns to suffocating crystals and plants lush with moisture are suddenly confronted with arctic air. From perennials such as Echinacea, Salvias and Agastache, to most drought adapted shrubs and trees it imparts hardiness. And I’m not talking about removing all the soil and lacing it with pumice- slopes, even gentle slopes count for a lot. Annual top dresses of organic material increases the oxygen in the soil. So many plants need to breath and just a moment of work can yield great success.



Summertime and heat and ripening

One last component to rating the hardiness of a plant is the amount of heat that it requires to achieve cold hardiness. Plants from very hot climates are adapted to a certain amount of ripening to achieve their ultimate cold tolerance. High summer temperatures converts green wood to brown, it accumulates calories in foliage and it can spur plants into bloom to complete their annual life cycle. They are adapted to this. When plants receive inadequate hardening they are way more susceptible to cold damage in the ensuing winter. Another facet is growing a plant in soil that is too rich. Many plants from mediterranean climates are adapted to dry somewhat impoverished conditions. Rosemary, Cistus, Arctostaphylos are adapted to a period of summer dry conditions. This pushes them into a second type of dormancy and prepares them for winter. Some plants just don’t like it fat and happy. Its important then to know where a plant is native, lower latitudes, deserts, subtropical environs this can tell you a lot about a plant. An example is Loropetalum (Fringeflower) it is native to subtropical SW China which can get surprisingly cold in winter. In the Portland area we receive just enough heat for this plant to survive our winters. Its not recommended for Puget Sound because their cooler summers don’t allow for ripening and it can freeze away at surprisingly warm temperature. A shocking number of plants register this same necessity. Daphne, Nandina, Camellias are just other examples where this is a factor. And I figure this into our local climate when assigning hardiness.

When things go horribly wrong

For almost all plants autumn brings a period of shorter days and colder and colder conditions nudging plants safely into dormancy. Ideally, in our climate, you want successive mild frosts to harden plants for colder conditions that meet the middle of winter. Well, in the best of all possible world that happens. Instead our mild maritime climate saturates plants with moisture and temperatures hover in the 30º to 50ºF range. You actually want mild freezes to convert the chemicals in your plants to freeze protecting sugars. And all but the most tropical plants possess this capability. Even, Phormiums and Bananas can do it. But when an early (Nov 15-Dec. 15) arctic blast descends or a late freeze when plants have lost their dormancy real disaster occurs. Even perfectly hardy plants that are still in lush growth mode can fall victim. And I’m not talking about borderline plants I mean ALL plants. Luckily, that is a rare occurrence and many, many years can pass between these devastating conditions. In Portland it has occurred historically every 15-20 years or so. Its infrequent but good to know when you are assessing plants for our climate.

Lets put it all together

So, there are many factors in plant hardiness. My best advice is to follow the instructions on the label. And if there is inadequate information look up the plant. Pay attention to its native origins and when in doubt ask us for the most specific instructions possible. If a plant requires poor soil and little summer water- its for a reason. At Xera we don’t just grow plants because they are exotic – banish the hardiness, we have a real commitment to plants that succeed here. Its important not to dismiss an entire genus if you have lost it to a freeze- there is great, great variability within each category and we are always looking for the most dependable. We test plants rigorously before we release them to the public, in our own gardens as well as above ground containers and in the harshest possible environs at our wholesale nursery. I hope this sheds some light on how and why cold damage occurs. This past winter brought an exceptional test in that realm. Be patient, many plants can show recovery even deep into summer. We look for three things regarding plant damage. First immediate damage, second about 2-3 weeks following arctic conditions real damage is apparent and finally the first day above 70ºF in spring when a plant really breaks dormancy. That is when the most conspicuous problems become apparent. We’re looking forward to a great year at Xera. Climate adapted plants for gardeners in the Pacfic Northwest.








Whats in a zone?

Plant triage after a wild winter

Winter damage control

This winter has been tough on gardens- unlike something we’ve seen in a decade or more. Ice/Snow/wind have wrought havoc and I know of more than one gardener that is dreading the details when they go outside. Its important to note that many years can pass between large snow/ice events and those benign years can leave our trees and shrubs vulnerable. If it happened every year they would be better adapted.  I’m kind of a weather/plant nut. I’m obsessed with how weather interacts with plants. That is to say I’m not just fascinated by cold hardiness but I really am curious about which plants stand up best to the elements, all the elements. As a nursery owner, grower, and gardener for a LONG time in Oregon here are some things to look at and some ways to fix what winter 16’/17′ has wrought.

I wanna rock. ROCK!

That foot of heavy wet snow that fell on January 10, and then stayed around for a week was the icing on an already icy trio of storms. The snow came down fast and heavy and it started above freezing and then slipped below. That means the snow stuck to every conceivable stem, leaf, and twig. It was beautiful- for the first hour.  Then reality set in- our gardens were flattened.  In the following weeks many plants have rebounded. After an event like this I always have to tell myself to be patient. Elasticity is built into many plants and if you give it time then you will likely see a return to their former stature. Aside from broken branches  what is most likely to happen is that plants that have been tackled by jack frost will then rock. The entire plant has been loosened from the soil and has lost stability.   Thats not good. This instability can tear the roots and result in a permanently compromised plant.  To correct this first gently move the plant back to its upright position. Gently, you don’t want to tear the roots. Then, looking at the base of the plant notice any displaced soil. Firmly and gently use your foot to depress the soil to regain stability.   Some plants that are prone to this are fast growing like Arctostaphylos, Grevillea, Ceanothus, Daphne, Buddleia- and just about any newly installed plant. Once the plant is upright then find a large, heavy rock (good rocks are the friend of gardeners) and place the rock over the weakest side of the rootball. This will provide an anchor and deter further movement.

Our gardens were flattened. My Olive looked awful but regained its full stature.

Plant bondage

To further secure a shrub or tree you  may have to resort to staking. And it doesn’t have to be permanent. Often it will only be necessary through one growing season. Ideally your staking material should be as strong as possible. For this I use rebar which can be purchased in 4′ foot and longer construction lengths at home repair stores. Rebar is strong, doesn’t rot ( like bamboo or wood) and you can reuse it indefinitely. Best of all its relatively inconspicuous hidden in the center of a plant.  The best way to adhere the plant to the bar is to use generous lengths of garden velcro. If you don’t have it you must get some-its magical stuff. It allows the plant to grow without girdling the stems and you can easily re-adhere it to accommodate growth. Even better it lasts a long time and is re-useable. Make sure that the plant is back to its upright state and pick a strong stem that is near the base and then work your way up.  Adhere the trunk to the rebar which should be anchored strongly in the soil. In time- usually one growing season is sufficient, true stability is achieved and out comes the bar.

Weight loss for plants

If the plant still wants to rock more intense first aid may be required. Many plants that were top heavy prior to the snow load were completely knocked to the ground. I had shrubs, even trees that were prostrate under the snow for a long duration. If the plant does not want to become as vertical even as you’ve followed the above procedure  you can correct this by some selective and judicious pruning. Think carefully. Don’t go crazy and shear the whole shrub or tree, instead take note of the growth the plant can do without. Most often it is growth from the previous season. Carefully cut out the top heavy branches. Think of this as sculpting the plant- and you are relieving the plant of weight to achieve a balance that ensures stability.  Be thoughtful as you remove material until you come into a size that the plant can stand up on its own. You are helping the plant to recover- remember that the green material on the plant exerts the most weight- you will likely not have to prune into leafless wood unless it is unavoidable. You may even not need to remove more than one or two branches.  Make your cuts with a sharp pruner and make them firm and deliberate. No wimpy cuts that tear. For branches that are broken make sure to make a clean cut BELOW the break. It may make you wince but often this kind of damage results in spontaneous growth. Its natures way of repairing damage. Take heart.

Tree inspection time.

After repeated bouts of freezing rain and snow I always take a moment to go around and inspect every one of my trees and even the neighbors if they are relevant to my garden. If you spot broken limbs look carefully at the wound. Did the broken branch snap cleanly (this is rare) or did it tear part of the tree bark along with it. You may need to go in and do some surgery. If possible cut the torn branch or whats left of it cleanly so the wound is contained. If it requires major surgery the city is full of talented tree people who you can hire to do the repairs. What you don’t want is a wound that becomes larger or can leave the tree open to infection by disease, rot or insects. Be aware of dead cling-on branches. They are branches that have broken but do not detach. They hang conspicuously in the crowns of trees.  Plums, Oregon White Oak, Callery Pears and many other deciduous trees are prone to this. If its unreachable, again call the tree guys. These are dangerous because they can detach at any time and some of the branches that are suspended can weigh a lot and cause damage when they fall. Including damage to the gardener. Look for limbs that appear out of place- the heavy and long duration of snow and ice put extreme pressure on every limb and there can stress fractures that are not immediately evident.  If you don’t spot this immediately it usually becomes apparent in the growing season by a part of the tree that is lack luster. The real evidence comes in autumn where a weakened part of a deciduous tree will often display fall color weeks in advance of the rest of the tree. That part of the tree has been compromised and is at risk. Keep an eye on that part of tree.

Garden round up

If you incurred a lot of damage in your garden the best advice is that time heals most wounds. Go around your garden and check for rocking plants. Give them a firm wiggle and stomp at the base to make sure they are secure in their given spot. I’ve chosen to keep this blog post short  so as not to overwhelm gardeners with too many tasks. Stay tuned and my next discussion will be on damage from cold and how to manage that. We’ve moved our opening date at Xera to Saturday, February 11. We have a LOT of new plants this year that we are excited to share with PNW gardeners.



Plant triage after a wild winter


Days and days

If someone had told me that the first 17 days of January in Portland would be below freezing I would have laughed- recoiled in horror but laughed. Well, woo wee we just did that and some of the lows were pretty far down the slope as well. In most years the repeated arctic episodes we experienced in December would qualify as a “real winter”. But it just kept coming.  I had a feeling we would have a real winter, but what we have been through so far exceeds my wildest presumptions. In the past we’ve had what I call Columbia Gorge Winters – winters dominated by easterly flow with arctic air entrenched east of the mountains- our source of frigidity. The colossal snow and ice winters of 1992/1993, 1979/1980, 1968/1969, 1949/ 1950 are examples of Columbia Gorge winters. That is there were unbroken repeated intrusions of air from the east and repeated snow and ice events.  This winter will go down in history (and its but exactly half over) as one of those winters. Notice that there are about 20 years separating those events. So we are looking at a winter we can expect once in 20 years. And it has been a LONG time since we last experienced one. Earlier in the 20th Century they were more frequent which is interesting to note.

December to remember

In a normal year the events of December would classify as a real winter. Nineteen days below freezing, two snowfalls, two ice events and an average low of 32.2º. Temperatures way below normal following what was our mildest November, it was something of a shock. And for those of us in N and NE Portland  there was a very damaging ice storm. I’m in north Portland and the ice was most damaging there and to the east in town. Other parts of the metro area were spared the 3/4″ of ice that caused so much localized destruction.  We can expect at least one Columbia Gorge event each year in Portland, and a truly arctic event every three to four years. If I was a betting man I would have said that December was the sum total of winter 2016/17.

Over achiever- January 2017

From the first through the 17th we had lows below freezing and our warmest high was a meager 41ºF. And a surprising six days had lows in the teens at the airport. Over a thirty year period we average 2 days below 20ºF per year- and that usually happens with regularity every three to four years. We doubled that so far this January.  The snowfall of January 10/11 was the piece de resistance and never have I seen a low pressure target the metro area with such an intense amount of snow in such a short period of time. I even had thundersnow at my house- I saw a flash and then heard the muted rumbling. I dismissed it as a blown transformer at first but when the rumble kept going I was really shocked. Its a snowfall that exceeded snowmageddon of 2008 because it was just one condensed event and 2008 was a series of three storms. If you throw out 2008 it was the most snow to fall in the city since 1980. A long time. In most parts of the city it was the most snow in one event since January 1943. Whoa.

Snow and cold- a reinforcing pair

Arctic air that flowed into the Columbia basin/eastern Oregon had a continuous reinforcing source with a jet stream from the north. Subzero temperatures there provided a source of the cold immensely dry air that has fueled the weather this month. Remember that low pressure to the south and west of Portland and high pressure east of the mountains provides a gradient that sucks air through the Gorge and it enters the the Portland Metro area and then due to the coriolis  effect curves to the left and fills the Willamette Valley – usually as far south as Eugene. This year it was not only the gorge as the primary  conduit of air- early in the month a large push of arctic air crossed the mountains all the way into Southern Oregon- there Medford recorded its most snow in one event (8.1″) that hadn’t occurred since 1919 (1919!!!). Substantial snow accumulated on the southern Oregon Coast in locations which hadn’t seen it since 1990. Truly remarkable. And this set the stage for the arctic events that were to come. Record breaking snowfall in the Columbia basin and Central Oregon meant that temperatures were not modified between each reinforcing wave of arctic air. Snow covered land refrigerates- and it enhances the evacuation of long wave radiation – read: it gets really cold. The ice box was primed and ready. This was to happen in Portland following our mini-blizzard- (stay tuned I’ll get to that).  So, the stage was set with a source of cold air and regime that kept the east wind blowing.

The snow that fell came down fast and was wet and heavy this maximized the damage.

The atmosphere for really cold temperatures.

Following the mini-blizzard the city was set up to experience some very frigid nights. Cold, arctic high pressure (not historically cold either) set up and gave us day after day of brilliant sunny weather and clear nights. The east wind even gained in intensity forcing cold air into the metro area over the snow covered surface. It could have led to crippling cold for almost all of us  but this did not happen. The strongest winds coming through the Gorge were restricted to the west end – Multnomah Falls to Troutdale  and then much diminished through the metro area. Its important to reiterate that wind actually keeps the temperature up.  The atmosphere naturally inverts, cold air sinks to the lowest points  while warm air escapes via long wave radiation to the sky. Wind keeps the lower levels of the atmosphere mixed and interrupts the evacuation of heat.   The coldest conditions occur on perfectly calm nights over snow covered terrain.  So, though the wind feels horribly cold due to windchill, and dry arctic wind can damage plants its calm conditions when temperatures really plunge.

Most of us dodged a bullet

On the 13th as high pressure built over Portland and deep snow cover had not begun to melt I was convinced we would dip to devastating lows. Luckily, that night and early morning there was just enough of a drifting east wind to prevent a plunge. At the airport the temperature which had been hovering at 20ºF all night took a perilous dip to 11ºF at 7am. The wind had stopped. This shows how volatile the airmass was. Luckily, the wind returned in the next hour and the temperature rebounded. All over the city the difference between Antarctica and relatively mild 20ºF lows was the capriciousness of a 5-10mph breeze. At Greg’s house in NE his low was just 21ºF- the same time 11ºF was recorded at PDX one and a half miles away. My low was 16ºF. But many areas repeated the temps that Greg recorded. One location that was not as lucky and which is often the coldest in the metro area was the Hillsboro Airport. Again, farther away from the winds of the Gorge it is a low and calm place and coupled with 8″ of snow it allowed the mercury to plunge that night to 3ºF. Probably very damaging to gardens there. And the coldest temperatures at an official reporting station in Western Oregon in four years.

Wait and see

So the real news of this winter so far has been the duration of the cold and as well as snow cover. The overall intensity of the cold has not been historic (Jan.13, 11ºF) broke the record of 14ºF for the date. In my own garden I’ve noticed very little cold damage as it begins to thaw. Some of of my intentional indicator plants show that damage will not even exceed the last arctic year of December 2013. This gives me hope. What I am really astounded by is the amount of damage that 13″ of heavy wet snow can do to trees and shrubs. All over town trees suffered horribly- possibly the most damage from a cold event since the great Ice Storm of Dec. 26, 1996. And even very surprising species succumbed. Downtown huge Ginkgo trees surrounding the First Presbyterian Church lost immense limbs- a tree known for its ability to endure winters wrath. A friend has a great theory that its the extraordinary time and benign intervals between events that sets all of our trees up for damage when it happens. This is most likely true.  If you are anticipating cold damage it is most prudent to wait at least two weeks before true damage is apparent. It should show by then. Then, wait until the first day in spring above 70ºF- this is the most telling and you have even given it time to break dormancy and grow. Patience often pays off. For plants damaged by snow or those that look bent beyond hope. There is hope. Most trees and shrubs have great elasticity and over the next few months will correct the misshapen  habit they have now. Give them time before you go hog wild with the pruners.

Even Ginkgos succumbed to storm damage

The second half of winter.

It will be fascinating to see if we return to what has been a stubborn weather regime for the past month and a half. At the moment we are enjoying a much more normal and deserved thaw. Pay close attention to long range weather forecasts. The NOAA Portland has done a fantastic job in its prognostications so far this winter. Remember that Presidents Day/Valentines Day is normally the end to when we can still have arctic air. Which is why it is often recommended as the time for pruning many garden plants. Our Shop will be opening on February 9th, barring any more arctic intrusions. Greg and I will be organizing a symposium for gardeners at the shop to discuss what failed and what sailed through this winter. If not for just some moral support. Thanks.


January 18, 2017


READY for 2017? Here’s what we’re working on at Xera.

Every year we focus on certain plants that we feel are excellent. After we have observed them for a number of years we see their star potential. They may be our own introductions, they may be just obscure but they deserve wider distribution. This year we are focused on shrubs. While we have an enormous inventory of Manzanitas there are many new varieties we are bringing to the market. It seems you can never have enough Manzanitas and we think thats the way it should be. Here Are some trees and shrubs whose excellent, reliable performance has impressed us. We love to share these plants with gardeners- discovery on all levels of gardening is a thrill. Check out these five shrubs/trees we are making in quantity. We think they will shine in your garden.

Grevillea x ‘Neil Bell’


7′ tall and   7′ wide in 5 years

Tomato Red Flowers

Bloom time: Year round

Zone 7b (5º to 10ºF)

Growth rate: Fast

Drought tolerant

Full sun to light shade

Well drained soil

Deer resistant

‘Neil Bell’ Spiderflower

This seedling was found in the garden of OSU extension agent Neil Bell near Monmouth, Oregon. Its parent is likely Grevillea x ‘Constance’. Neil thought it had promise so we took cuttings and what it has yielded is a fantastic shrub. Hardier to cold than its seed parent by a good 10ºF we have never had damage down to 5ºF, extraordinary. Its a handsome fast growing evergreen shrub quickly to 7′ x 7′ in just 5 years. Its best attribute is its YEAR ROUND heavy flowering. Large pendant spiderlike flowers are vivid tomato red and will open happily in all temperatures down to freezing.

The open flowers are cold hardy to approximately 25ºF (-4ºC) and if they are damaged flowers in the bud stage are hardier- protected by fine hairs and subsequent weeks will open happily. Full sun to part shade in the hottest aspect. Not fussy about soil as long as it is never boggy. ‘Neil’ is completely unphased when unirrigated in the hottest weather- never requires summer irrigation.  If your plant is shy to bloom it may be tip pruned at any time of the year. This seems to spur Grevilleas into bloom – just remove the very tip of each branch. It will also increase the shrubs density.


Lagerstroemia x fauriei ‘Yuma’


12′ tall and   6′ wide in 5 years

Light bluish lavender

Bloom time: Late July to Sept.

Zone 6b (-5º to 0ºF)

Growth rate: Moderate

Regular summer water

Full sun

Rich soil, especially clay

Fall color- Orange/red

Bark: Taupe/tan/pink

‘Yuma’ Crape Myrtle

I’ve grown a LOT of Crape Myrtles in Western Oregon and I’ve had about 30 years to sufficiently gauge the best performers. Our summers are not as sweltering as the SE U.S. or interior California and Crape Myrtles with the lowest heat requirements to bloom have always been the best. This spectacular tree has surprised me again and again. I never thought lavender/bluish would be the color that I found most spectacular but there are several reasons why ‘Yuma’ changed my opinion and makes it my FAVORITE Crape Myrtle in our climate hands down.

The flowers show up reliably even in cooler than average summers- most often in town in late July. The trusses of flowers are a luminous hue and they are HUGE, FULL, and over the top OPULENT- substance makes up for the less bright flower color and exceeds it. Its habit is unusual for Crape trees. Rather than the rigid upright to pendulous branches on most other cultivars this one produces a spreading sinuous slightly angular crown that is not only graceful it excels at featuring the HUGE flower trusses. The bark is a showy combination of russet/taupe/pink and remains striking year round. Finally it has very impressive and consistent fall color. A combination of smoldering bright orange and red. Regular water is necessary for this small moderately fast growing tree to perform.

Nerium oleander ‘Hardy Red’



5′ tall and 5′ wide in 6 years

Red/Magenta flowers

Bloom time: Late June to Sept.

Zone 8a (10º to 15ºF)- Survives lower with establishment

Growth rate: Moderate

Regular water to dry

Full sun – a hot position

Rich soil, good drainage

‘Hardy Red’ Oleander

I’ll have to admit that I planted this Oleander just to see how ‘hardy’ hardy truly is and I’ve been thrilled with this shrubs performance. In its first year as a youngin’ it breezed through 9ºF and the evil double freeze winter of 2013/2014 with just a few crispy leaves. I wasn’t prepared for it to repair itself so quickly in spring and commence full bloom by June. All of my preconceptions about this as a highway ornament that ubiquitously lines the freeways in California went right out the window. It begins blooming and then on new wood it produces a continuous supply of vivid, incredibly showy flowers for more than two months. Well worth its weight in mid to late summer.

In our climate ‘Hardy Red’ has been slower to bulk up than in milder zones but it still puts on about 2′ of growth a year. I think its going to be most successful as a garden shrub in the urban heat core of Portland. Cold damage begins in the low teens- but again recovery is ultimately fast. We grow 3 other ‘Hardy’ Oleanders but this one is my favorite as I’ve always had a soft spot for the red flowered variety in this species. Full, hot sun and light summer water in well drained soil. Mine is located on the SW corner of my house near a west wall- adds a little protection. And I’ve planted another in a full open exposure just to see how it fares. We are also growing ‘Hardy Pink’, ‘Hardy White’, and ‘Mathilde Ferriar’ (double yellow flowers). These should be more than reliable in mild urban places.



Hydrangea quercifolia ‘Munchkin’

3′ x 3′ in 7 years

White /green flowers

Bloom time: May-July

Zone 5a (-20º to -15ºF)

Growth rate: Slow

Average water

Full sun to high overhead shade

Rich soil, well drained

‘Munchkin’ Oak Leaf Hydrangea


Oak Leaf Hydrangea has long been one of our favorite shrubs at Xera but the problem is that they almost all get enormous. And the few that were touted as compact would often not bloom very well. But forget all that. The National Arboretum has come up with a stellar version of this tough, dependable and multifaceted shrub. To just 3′ by 3′ in 7 years this truly compact plant also explodes into bloom from every densely branched tip. And the flowers aren’t small, they can be cones of creamy white and green up to 1′ long. A shrub in bloom is magical. As the summer goes along the flowers age to a rosy pink and extends the show well into autumn.

This dainty shrub has a wonderful congested habit and it displays the huge white cone shaped trusses of flower in every direction. In late autumn/winter the large substantial leaves take on burning tones of red and maroon. By spring it is a clean little deciduous shrub. Full sun to light shade in rich soil with regular summer water brings the best performance- but established plants seem to get by on their own. This is a fantastic plant and it brings this wonderful species into the smallest gardens. No pruning is required. We’re the number one fans of ‘Munchkin’.



Callistemon ‘Wetlands Challenged Mutant’

You simply don’t see this flower form often in our climate- so its spectacular and welcome

5′ x 4′ in 7 years

White /Cream

Bloom time: May-June

Zone 7b (5º to 10ºF)

Growth rate: Moderately slow

Average water to dry

Full sun to high overhead shade

Rich soil, well drained

‘Wetlands Challenged Mutant’ Bottlebrush.

At Xera we are fascinated by bottlebrushes. More and more we are finding excellent species and cultivars that thrive in our climate. This is perhaps one of the best. Raised and named by Ian Barclay at Desert Northwest Nursery in Sequim, WA we are entranced when this hardy evergreen shrub blooms. Huge 5″ long by 1″ wide ivory cream brushes decorate the modest stems in mid to late spring and often again in early autumn. Not only is it showy in bloom its a really nice looking plant as well. Army green relatively large leaves make this plant glow. Though it has a very light texture this is a  substantial shrub for a hardy Callistemon.

Slow growing it will reach 5′ only after a half dozen years. Full sun to (surprisingly) very light shade in average soils suit it. Its even ammenable to heavy clay on slopes. Light summer water speeds growth and I suspect enhances the bloom show of the following year. This is a spectacular shrub for those who seek the original. Excellent selection made by our friend Ian and it should be one of the most popular. Somewhat deer resistant. The name refers to a character in the long defunct cartoon ‘The Neighborhood’- either way its a great shrub.

So here is a glimpse of the future- we think these plants have true star potential. There’s nothing more exciting than trying new things- and if you plant enough new stuff you are sure to find a diamond in the rough. Look for these plants next spring when we open.

Have a wonderful Holiday Season and a Happy New Year!




READY for 2017? Here’s what we’re working on at Xera.

Pruning guide- Shrubs, Manzanitas

Shrubs and pruning

Working in both wholesale and retail and selling a LOT of unusual shrubs I can tell you that one of the most perplexing issues facing a new gardener is pruning. People are deathly afraid of doing it wrong and as we’ve seen more than our share of butchering by landscrapers in this climate there should be some healthy fear. The problem is there are literally thousands of shrubs that thrive in our climate. And I’ll try to impart my best advice on how to approach this. This blog post is about pruning shrubs, I’m not going to go into trees and vines but some of the advice may be applicable.

Do you need to prune at all?

That is a great question. Most pruning is done to restrict the size of a shrub that is too big for its allotted space anyway. The first and most important thing you should do before planting is get a realistic size for your prospective beauty. When I write our tags I try to give the best estimate of what that ultimate size may be. To be honest very few shrubs stop growing- they may just grow slower and so that adds to my dilemma. In some cases I give the size in 5-7-10 year increments. A garden changes an awful lot in that time frame but at least it gives the gardener perspective. Some of the most important ideas to consider are the location, water availability, and soil conditions.

Too Fat and Happy

For instance, many cultivars of Ceanothus that we grow are California derivatives. They were selected in a climate with MUCH less spring rainfall and soils that are less than perfect. I learned early on to factor in the PNW conditions and basically double the size of these shrubs on our tags. Remember, rich soil (ideal conditions) and availability of water can send a shrub from a less fat and happy climate soaring. That little Ceanothus ‘Concha’ that you plant here can reach tree-like status very quickly. Its funny to see it growing in California where it is a nice restrained plant. Thats why we don’t advise improving the soil with many west coast, mediterranean, Australian, Chilean shrubs. Not only is there no reason to do this you may actually shorten the plants lifespan or leave it open to fungal root pathogens, it can also nudge slightly tender plants into perpetual growth- they never shut down for the approaching winter. That means that they are MUCH less hardy to cold in winter. Summer drought adapted shrubs (West Coast, etc) are used to growing in spring and then going into a second dormancy related to summer drought- they require this to meet their ultimate cold hardiness. Some shrubs that fit into this category are the aforementioned Ceanothus- Cistus, Arctostaphylos, Rosemary, Myrtus, Grevillea- and many other broadleaved evergreens can be nipped or killed, especially by a November or early December Arctic event. The moral is to trust the plants and give them what they are adapted to do. Organize them in your garden by water need or neglect- think of your garden in terms of biomes that you create.  What does this have to do with pruning?

You made me do it.

Pruning can do quite a few things to a shrub. It can restrict the size, it can make a lanky plant fuller, and it can spur many plants into boisterous growth. The first thing you need to know about pruning is how it will affect the plant. Imagine when a plant is pruned in its native habitat. Deer, as an example, can browse many shrubs and the shrubs best defense is to sprout like crazy and replace the lost photosynthetic material with much more. The plant grows into a dense ball of foliage. It may also be said that more light and wind makes a more compact plant and even small compact shrubs can grow openly (lanky) in less sunlight. But if you are unsure how a shrub is going to react- and no tag is big enough to address that and books almost NEVER mention it. Then you need to rely on that most important of all gardening skills OBSERVATION. Make a little test cut on the shrub and see how it responds. Stay tuned and I’ll give you an example of when to do this. But Its important to note that where on the shrub you prune, how you prune it, and most importantly where the shrub is adapted to grow dictates your results.

Some important terms to guide your results

One of the most disastrous outcomes of improper pruning is to eliminate the flowers and thus render a flowering shrub a foliage only plant. Many people who go whole hog pruning on the first warm day in March probably can’t understand why their Rhododendron, Camellia, Lilac, and many other shrubs then don’t bloom- they’ve eliminated that years flower buds. So, I like to refer to OLD wood- shrubs that bloom on one to two year old wood and NEW wood- flowers born on current season growth. This is where observation is your guide. If you HAVE to prune make sure that your first test prune is right AFTER a plant has bloomed. This will almost always put you in safe territory. Shrubs that bloom on old wood grow  after flowering and then set their buds in the summer to fall for the following season. If you then prune when the shrub is in its current season of growth you can still allow the shrub time to grow and set buds in the ensuing summer. Some shrubs besides those already mentioned that bloom on old wood are Viburnum, Berberis, Leptospermum, Osmanthus, Pittosporum, Pieris. If you do measured and careful pruning right after bloom and before flower bud set you won’t wreck next years show.

Lagerstroemia x fauriei ‘Wichita’- Over pruning Crape Myrtles is not necessary and is called ‘Crape Murder’. Little or Light pruning is sufficient. An example of pruning on New wood.

Why would I prune on new wood? 

The most immediate reaction of a shrub to pruning is to branch. On most when you take out the terminal branch bud then that causes the plant to double its growth output. Like a deer browsing the effect is to cause the plant to increase the amount of wood and foliage. Its what nature tells them to do. So, on shrubs that bloom on NEW wood- the current seasons growth pruning can increase the amount of flowers that you achieve in the season. The most applicable example of this is Hybrid Tea Roses. By pruning them back you increase the amount of blooming wood. (Remember that ALL roses do not bloom on new wood- so you should, YES, OBSERVE for a season and do a few test cuts-most roses that bloom on old wood are once blooming.) Pruning of these plants should be done in our climate on or AFTER Presidents Day, Valentine’s Day- mid February. Then we are safe from arctic cold and the growing season has not yet started. Some shrubs that benefit from this are Vitex (Chaste Tree), Shrubby Crape Myrtles (prune lightly), Buplerum fruticosum,  Deciduous Ceanothus (‘Topaz’, ‘Henri de Fosse’, ‘Glory of Versaille),  Indigofera, Oleanders, Jasmine.

Radical Pruning- if you really have to do it.

Sometimes a tired old plant or enormous thing you’ve been gifted by a previous gardener can benefit from some hard core intense pruning. You may be able to resize the plant, reshape it, and reinvigorate it with hard pruning. I’ve seen this accomplished on arboreal Camellias, Rhododendrons, many things. First the plant has to have what are referred to as dormant buds. That is leafless wood on the large branches or trunk that has dormant buds that you can’t see but will be activated in the case of a radical pruning. The best way to achieve the results of a radical pruning is not to just chop the whole thing down all at once. This shocks the plant and though it will respond with the resources of a large root system it can be too much. Rather do measured removal in a few seasons of  no more than 1/3rd of the plant at a time. Though its not pretty and it undoubtedly sacrifices a year or more of bloom it can work. I suggest that you keep the plant well watered during the dry summer to decrease stress.  Some plants that benefit from radical regenerative pruning are: Yews (Taxus), Osmanthus, Lilacs, Hibiscus, Arbutus unedo, Pyracantha. Plants that definitely don’t are Cupressus, Cistus, Ceanothus (evergreen kinds).

Pruning Manzanitas follows slightly different rules.

Manzanita- a pruning primer

One shrub that we LOVE and sell a lot of is Arctostaphylos (Manzanita). I’m going to go into a more specific example of how to prune them because its a little different. Arctostaphylos are grown for their foliage, flowers, AND dramatic bark. Here are a few pointers to get the most out of them. They bloom on OLD wood. That is they grow after winter and spring blooming then set the flower buds for the following season. Tip pruning- is a term that you hear and this is what it is: twigs of the most recent years growth will be clothed in leaves. Tip pruning is just that, after blooming you tip out the bud on the new growth. Thats between any leaves on the stem. On Arctostaphylos the wood grows distinctly. What we call green wood may be pruned and dead wood or leafless wood which will not re-sprout if hard pruned- think of the bare trunks of the Manzanita- there are NO dormant buds.  Tip pruning can apply to any shrub and it does a few different things. If forces the green wood to branch and can lead to an over all denser habit. It will then lead to more tips to produce flowers. This should be done directly AFTER blooming has finished. In the case of many evergreen shrubs the canopy of leaf cover will shade out the lower leaves and they will drop leaving bare legs. If you want to expose the dramatic trunks simply prune off any dead stems cleanly at the surface of the trunk. This increases not only your view but enhances air circulation which Manzanitas dearly love. To complicate it a bit more certain Manzanitas will create what is called a burl at the soil base. This swollen rounded dome of wood contains  dormant buds. It is an adaptation of fire in its native environs. If a burl is present the whole shrub can be cut back to that and regeneration will occur. So, leafless wood on a Manzanita will NOT sprout if cut, green wood with leaves will sprout and if a burl is present regenerative radical pruning can be done.

Slicing and dicing

Remember that when you prune that hygiene is of utmost importance. Keep a clean, sharp secatur and make your cuts thoughtfully. Make cuts on a slight diagonal plane and make them firm and hard. No wimpy cuts that tear or mangle. If you are pruning for shape and results don’t just get in there and start hacking. Make a cut. Step back, look at it and then make the next cut. To be honest most shrubs are fairly forgiving. Be thoughtful and you will achieve your desired results.

Xera Plants will be closing on November 6th for our winter hiatus. We’ll be back open in February barring any arctic events. I’ll still be blogging and posting them on our Facebook page and website. Look for a new website in January 2017. Happy Thanks Giving.


Pruning guide- Shrubs, Manzanitas

A sample of winning plants that I wouldn’t be without.

I thought I would do a different blog this time. Instead of talking about the weather I decided to share some of the plants that I couldn’t be without. I’m exposed to thousands of plants because of my profession. Greg would agree that we are are total plant whores. I love, love, love finding a new plant and testing it out in my garden. In fact my garden isn’t the most aesthetically consistent. I try new plants all the time. What this entails is plunking the plant straight into my un-ammended soil and getting it established. I figure that most people don’t have the time or resources or continuity to make the soil perfect for individual plants. In my garden its sink or swim. Here are some plants that I think are perfectly adapted to our climate. Plants that I wouldn’t be without.


Agave bracteosa (Zn7a) and Yucca linearifolia (Zn7a)

Agave bracteosa & Yucca linearifolia (Zn7a 0ºF)

Two plants that I find completely indispensable in my garden are these two easy to grow Mexicans. Agave bracteosa is perhaps one of the easiest Agaves to grow in Portland. Sometimes called the Octopus Agave I love its easy ways, and non-lethal leaves. This dear plant thrives in very well drained soil and forms a substantial plant quickly. Mine are located in the partial shade of a ‘Summer Chocolate’ Albizia. I love that it suckers freely and I can detach and move them all around my garden. On a scale of 1-10 I give this remarkably adaptable large succulent a 10.    Just north of the Agave in this picture is another nearly flawless plant. Its the ultimately symmetrical, always erupting stunning Yucca linearifolia. Its a new comer from Mexico as well but it LOVES the gravely well drained soil of my parking strip. I have three in a group and they have been spotless through five winters as well as precipitous lows. Its a perfect plant. I love to stare directly into the rosette, its symmetry is dizzying and always makes me smile, smile, smile. This Yucca has become very rare on the market and all I can advise is buy it immediately if you see it offered. Immediately.

Jasminum officinale ‘Affine’ (Zn7a)

Jasminum offiinale ‘Affine’ (Zn7a 0ºF)

On a totally different note I thought I’d share my favorite vine. Sure, it doesn’t have 6″ wide flowers and smother itself in color but what it does offer I love. Jasminum officinale ‘Affine’ earns top marks in my garden for several reasons. First, its totally adapted to our climate, cold hardy, drought tolerant, and remarkably vigorous. This regal vine, also known as Poet’s Jasmine takes up vertical real estate but its well worth it. Heavily in all of June and then sporadically through summer it delights with clusters of 1″ wide crystal white flowers with the worlds most exquisite perfume. June wouldn’t be June without the wafting perfume of this elegant, romantic vine. In fall the pinnate leaves turn to tones of apricot and fawn before dropping. To 15’+ it deserves a place on every large pergola in western Oregon. New growth on this vigorous cultivar is a stunning deep burgundy. Light summer water and nearly any soil. Full sun to quite a bit of shade.

Fatsia japonica ‘Variegata’ Zn7a

Fatsia japonica ‘Variegata’ (Zn7a 0ºF)

A good friend of mine and the owner of a large nursery in California once told me that “foliage is king”. I have to whole heartedly agree. Fatsia is a wonderful plant to grow in our climate. Its bold and undemanding and suffers the rigors of dry shade with nearly bionic aplomb. My favorite is plain old ‘Variegata’. Its huge evergreen leaves are irreverently edged in white. Perhaps its most remarkable trick is to have huge candelabras of variegated, pure white orbicular flowers in autumn. To 6′ tall and half again as wide. We will have an enormous amount of this exact cultivar for sale in the spring. Deer shun it even as it imparts the toughest display of tropical foliage. Easy and hardy.


Digitalis x ‘Honey Trumpet’ (Zn5b)

Digitalis x ‘Honey Trumpet’ (Zn5b -15ºF)

This is pretty self indulgent but I have to plug this remarkable hybrid Digitalis that emerged at our nursery. The product of a tetraploid yellow foxglove and a semi-shrubby species what you get is a sterile but blooming machine. Tubular amber imbued trumpets line tall spikes from May to October. Cut back the spent scapes on this long lived perennial and more will arise. It thrives in full sun and  many types of  soil. Its Iberian heritage means that it thrives despite our dust dry summers. To 28″ tall and producing multiple scapes. Perfect in a perennial border or adaptable to xeric realms. Regular water in full sun sends this foxglove soaring


Arctostaphylos x ‘White Lanterns’ (Zn7a)

Arctostaphylos x ‘White Lanterns’ (Zn7a 0ºF)

Manzanita. Everyone in our region should have at least one. They are the ultimate shrubs of the west. And WOW what they offer is a four season display of bark, foliage, and flowers. I’ve grown a shitload of Arctostaphylos and I can tell you that some are great garden plants but many species are determined to be feral. This smaller growing shrub is a perfect plant as far as I am concerned. Small, dapper leaves- held perpendicular to the sun to avoid moisture loss- are a fine textured bonanza. To just 3′ x 3′ it finds a home in the smallest gardens. And holy smokes it offers smooth cinnamon bark with age and a reliable display of  profuse white flowers in late winter. As with all in this wild genus it thrives on utter neglect. ‘White Lanterns’ has been a stellar performer at the OSU North Willamette Experimental Station. And I completely agree. Its a fantastic, adaptable, disease free, cold hardy cultivar.

Callistemon viridiflorus (Zn7b)

Callistemon viridiflorus (Zn7b 5ºF)

This groovy bottlebrush should be everywhere. Diamond shaped forest green leaves line the corky white stems. In May-July it erupts in delicious chartreuse brushes. This 7’x 5′ evergreen shrub loves full sun in our climate. Its a boon for pollinators as well as hummingbirds. A native of Tasmania it actually needs cold for a good flower set- and our region is ideal. In its native haunts it dutifully follows cold air drainages in canyons to achieve its perfect adaptation. We have been experimenting with this species and have selected three distinct varietals. ‘Shamrock’ is  a tidy compact but decidedly upright cultivar. ‘Xera Compact’ is exactly that but with an unmatched profusion of bloom. ‘Xera Hedgehog’ is but 2′ x 2′ with a copious display of chartreuse brushes. It could find a perfect home in the sun drenched tough life of parking lot islands. Light summer water.

Osmanthus x fortunei ‘San Jose’ (Zn7b)

Osmanthus x fortunei ‘San Jose’ (Zn7b 5ºF)

I have a thing for fragrance in my garden and when you pair that with a handsome glossy evergreen shrub…woo, I’m there. This hybrid Tea Olive is just the ticket. In time it achieves tree like status but I prefer it as a large shrub with leaves from the ground to the top. In Oct/Nov. it produces small parchment colored flowers with the penetrating perfume of apricot and freesia. Mine is 25′ from my back porch but when the weak but warm autumn sun blazes it sends the perfume on a roaming path to my house. Easily grown in almost any soil, once up and going it is completely tolerant of our summer drought. Whatever you do, don’t forget autumn where some of the most sophisticated plants shine.

Grevillea  miqueliana (Zn7b)

Grevillea miqueliana (Zn7b 5ºF)

This Australian shrub was a pure experiment and its turned into a winner. Round Leaf Grevillea is the not so original common name of this large shrub which is less than common. Undulating round suede textured leaves are dapper year round. This large, dense evergreen shrub is fantastic in bloom from January to July. Pendant sunset colored flowers decorate the tips and delight gardeners as well as hummingbirds. Best with exceptional drainage such as a slope, but one of the most tolerant of clay soils. Grevilleas can be a challenge to grow  but with careful siting and deliberate neglect they are more than rewarding. Last winter we experienced a small freezing rain event. My Grevilleas were in full bloom. Peering out the window I watched as a hummer perched on a stem waiting patiently for the ice encased nectar rich flowers to thaw. A natural bird feeder and an elegant shrub.

Remember every season

We are so gifted in this climate to be able to grow a nearly endless palette of plants. I love testing new plants and I’ve come to respect these as reliable and dynamic additions to the garden. Gardens are not static, we begin them and then follow where they go. This group of plants I encourage you to try, include, enjoy in your own space. I’ll continue to try new and old plants to discern their adaptability. Trial and error is the essence of growing plants. All of these plants we grow at Xera. Have a good early October, one of the nicest times of the year in PDX.



A sample of winning plants that I wouldn’t be without.