2/3rd of winter down. What winter?

Winter in Portland is a tale of two climates and there are two important facts you should consider when gardening here. The first is that  our proximity to the Columbia River Gorge significantly influences our weather  and the second, is that winter here may or may not even show up.   And statistically that holds true. And climate is nothing if not held hostage by statistics. In the last 20 years we have had a major intrusion of arctic air (lows in the teens or lower with highs in the twenties or lower) once exactly every four years. That is both significant in its symmetry but also how consistent it has been for a surprisingly long time. The truth is we average 7 zone 9 (above 20ºF) winters out of 10 and  just three years per decade- for the past three decades that have slipped down to Zone 8 (below 20ºF)  Last year was the coldest winter overall (real meteorological winter Dec-Jan-Feb as measured by the NOAA) in 38 years! It was the first winter since 2013 where a real , deep, arctic  airmass came and stayed. It was the completely rare case of cold and snow repeating over and over – way out of sync with our normal climate and truly unusual. Time for a real perspective.

Say no to PTSD and garden in the present

It left a kind  of gardening PTSD (Portland Traumatic Snow Disorder)  that has carried over into this season. Here is a reason that you should get over last years trauma. It was somewhat inevitable statistically but still very rare and likely a one off occurrence.  Those same statistics that the majority of our winters are mild upholds this argument well. And this years return to mild weather is a further validation of lasts years rarity.  We hadn’t had weather that consistently cold and snowy and icy in four decades and it could easily  be that long again before a repeat looms.  So, let your trauma fade- status quo is on your side. As a child who grew up here and a complete  life long weather hound I can tell you how really difficult it is for snow to fall here. Last year was beyond a fluke, it was a once in a generation occurrence. Snow/ice is by far the hardest thing to predict here and the truth is a very specific succession of events must come together for it to happen at all. This years white christmas was another very rare fluke. Only 6 times in 150 years has snow been observed on the ground on Christmas Day in downtown Portland and it has only been recorded FALLING on Christmas twice.  The reality is that in a thirty year period we experience an average only 2.6″ of snow per year- thats spread out over a long time and includes the majority of years where NO snow is observed at all.  Last year was a HUGE anomaly and trauma may be complicit in gardeners fearing weather patterns will repeat. No fear, here are the real statistics. Let go of last years garden PTSD and live in the moment. This years refreshingly average moment.

December and January vastly different from last year.

Here’s an example of December’s weather, notice the profound two week warm and two week cold period in the first and second half of the month respectively.

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Fourteen days below freezing in December had me second guessing myself around Christmas.  Compare that to the similar total of 17 days below freezing in December 2016 and you’d think we were about to repeat last years Cold. However 2018 has begun very differently.  In fact, January 2018 has been the second mildest January of all time and the mildest since 2006. Check it out:

January18

 

 

A confused year but vigilance

As of now there is a weak La Nina, which forecasters have been very attached to in their forecasts. Each long range forecast has shown a wetter/colder future until that future arrives and models modify the temps and precipitation and winter is held off for another several weeks. For us at Xera it is a constant game of waiting. Our weather tends to operate in two week cycles. Two weeks mild – a ridge  (which usually involves fog and cold at the surface- inversion)  which makes us tend to not notice them as warm and two weeks cold a trough- stormy, cold, and rainy.  How cold we get is completely dependent  on the jet stream and its the way it orients the flow of air from the north or northeast. During cold regimes we are more likely to experience an ice/snow event or an arctic intrusion so we watch the weather then very carefully . However, there is a typical end to cold intrusions.   The past shows us that real arctic air after February 15 is incredibly rare and has only occurred twice in 100 years of record keeping. The door on cold air slams shut. There’s an old garden adage in Oregon that you wait until after Presidents Day to prune roses in earnest. Apparently wise advice and based on a long standing fact that a hard freeze is then unlikely

Arctic forecasts and evil retrogression

This two week alternating cold/warm  pattern is what we watch here at Xera.  (Its part of a global pattern that is very complex). A trough of low pressure in the upper atmosphere divides arctic air to the north from warmer high pressure to the south . As the jet stream plows along it produces these ridges and troughs ahead of it. They usually move along with regular alacrity.   If a strong trough sets up over the PNW it allows cold air to the south and a naturally occurring dome of high pressure can shift its position in the Gulf of Alaska. If this ridge expands and becomes stable its called a blocking ridge or a Rex Block. This becomes apparent in the forecast as the block of high pressure moves ever so slightly to the west- it retrogrades or moves opposite to the standard flow.  This sends the jet winding up and into Alaska/Yukon and then it makes a right hook and spills directly down from the north east over the PNW. Then high pressure east of the Cascades and relatively lower pressure over the ocean sucks cold, dense, dry arctic air through the Columbia River Gorge- a reversal of the more common western, zonal flow. Retrograde highs are the worst as they orient the flow NE to SW and deliver the coldest arctic air directly over us from the the north and northeast. We don’t like the word Retrograde at Xera. Bad word, very bad word. Luckily, with the help of statistics we know that it will happen in a major way about once every 5 years- a long time between events and they luckily are seldom a surprise- with quite a bit of forecast lead time with current models. Lesser intrusions of cold air follow this pattern too but often the cold air is shunted to the east of the Rocky Mountains and delivers us only a glancing blow- a few days of cold air pouring out of the gorge.

 

What if the jet stream fizzles? 

A retrograding high is the set up for a truly arctic air event and while we are in a colder two week scenario there is always the possibility of this arctic door opening.  If however, the trough moves through fairly quickly, a warm atmosphere replaces the trough of a cold atmosphere and there is no time for cold air to build. This is our more normal and consistent zonal (west to east) flow.  What has been happening in recent years is the prospect of a de-engergized jet stream. That is the typically huge temperature gradient from the poles to the tropics that energizes the jet stream may be failing.  The poles are heating up MUCH faster than the equatorial latitudes.  This depressed temperature gradient is having a profound implication for our weather. The jet has lost the fuel of a wide pressure gradient and we must prepare for a new pattern- AKA ‘The Lazy Jetstream’.   As I mentioned normally  ridges and troughs would move through the region quickly as the Jet stream propelled them across the upper latitudes. Arctic air was kept north of this active jetstream corralled as they say and weather also moved along much more consistently.

No denying change is happening

A weaker jet stream blows this all to hell.  Weather patterns become static and as ridges of high pressure persist they form huge troughs of cold air downstream. That has been the scenario this year over North America. The Western U.S. has had persistent ridging and the eastern U.S. with a straight north south trough orientation plunging cold air deeper and farther to the south- snow and ice to the Gulf of Mexico not once but three times so far this winter. The actual weather in the Arctic has been far above normal- all the cold air left- drained away with a lack of an atmospheric dam and as nature abhors a vacuum that cold air was replaced by lighter warm air- yet more warm weather in the arctic. The sluggish jet stream is changing the way we experience weather.  If you are persistently hot and dry that could continue for an extended time and the opposite is true cold and wet can persist.  It seems that once patterns take hold they have been loathe to get on out.  Could this have been an ingredient in last years persistent cold? At the moment an example of this is the persistent drought in California. A stubborn, stubborn ridge of high pressure has formed and re-formed over the winter months. Just a handful of storms have made it inland and they are facing a pretty dire return to drought unless things change drastically.  A sluggish jet stream will effect everything from flash droughts and heat waves that persist and build to an open gateway to the arctic where cold air simply bleeds far south unimpeded by a healthy intervening rapid jet stream.  In essence we could be looking at a sloppy mess. How this is impacted by a more energized, warmer atmosphere that can hold and release more water is just a piece of what is keeping climate scientists awake at night.  Its complex.  It has great implications from droughts to coastal storms virtually every way the weather is delivered. And I personally have been keeping close attention.

Predictions of an active cold winter evaporate

If I was observing this winter on paper without any other input I would swear that we are having an El Nino winter. Weak, splitty  storms and stretches of mild high pressure. Not at all what you would expect for a WEAK LA NINA- (La Nina is the colder and wetter climate cycle) and this appears to have tripped up forecasters this winter. La Nina has been factored into the forecasts but has simply failed to show up. I had a feeling based on this past summer and autumn and tossing in the statistics of arctic intrusion that we would see a repeat of the non-event mild winter of 2015/2016. And as my hunch was correct, that seems to be playing out.

 

Watching Climate Change in Real Time

In reality we are seeing climate change in real tangible ways.  If true it would dovetail with 2017 being the second warmest year ever recorded despite the fact that 2016 was the warmest- inflated by a strong El Nino (warmer Pacific). 2017 was expected to be significantly cooler as the large El Nino had dissolved into a weaker La Nina. The cooler waters were expected to buffer the planets overall fever.  Instead, 2017 was shockingly the second warmest year since record keeping began. Could it be that the real news is that the rate of global warming (not just climate change, but warming) has usurped stronger existing patterns and systems. We may have entered scary new territory. I’m sure this will be the subject of quite a bit of research……not by our pathetic denier government.  Remember that 17- yes 17 of the warmest years ever recorded have happened since 2000. Yep. Not a good time to deny.

Mildest January since 2006 which was the mildest of all

January has been extraordinarily mild and uneventful. Just TWO days below freezing rather than our average of 12. BTW Portland averages 26 days below freezing per year- this year we are at 16- as I said the majority being in December and not at all arctic. (Our low of 23ºF is right on average for mild years) we typically see a zone 9a winter for four out of five winters.  The long range forecasts for February at first showed a hint of cold air but as time has elapsed the models have inevitably trended warmer and warmer. In fact there is a good chance of sunny, dry warm weather for an extended period this month. Weak La Nina aside the most accurate forecast models keep pointing to a warm ridge of high pressure. It will be fun to see what comes to pass. An early spring? A famous False February Spring?

Groundhog Day is passe

So, despite the prediction of the groundhog in two days it appears the climate dice are set for the rest of this winter. Remember that we can still get a freeze up until April 15 and we could even see some wet snow. But real arctic cold is likely a memory. Wahoo.

Here’s to spring!

Happy planting in 2018!

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2/3rd of winter down. What winter?

You really move me

The seasons are changing and I’ll be posting consistently about the weather/gardening for the next few months.  Its been a great, if hot summer and I don’t know about you but I’m glad for the respite from watering. I get asked a lot of questions at the shop but the one that surprised me over and over was when and how to move a plant. I thought I’d give a few tips on how this may be done successfully. I get the impression that people are carting their plants all over their gardens with very mixed results. Here is how to do it and succeed.

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The right tool for the job

Moving a plant can be daunting and if you don’t have the right tool it can be downright arduous. The correct shovel not only ensures success it takes the toll off of your body. My favorite shovel and one that I think all gardeners should own is a ditching shovel. Unlike its clunky common cousin with a wide scoop, this shovel has a long 30″ blade that is just 5″ wide. The wooden shaft is only 3′ long and ends in a plastic or metal ‘D’ handle. The long blade is built for cutting into the ground precisely and will easily cruise right through heavy clay, even gravel, as well as woody roots. I use it for not just ditches and moving plants I use it for planting bulbs or carving a hole in a tight space anywhere you need to be precise.  This implement directs you to use your foot to absorb most of the effort and is much easier on your body as a whole. It makes a great gift for a gardener. Its sharp enough to pierce cleanly though perennials that require division  and when digging and moving a plant it is indispensable.

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A ditching Shovel is the right tool for moving plants.

The right time for the job

I’ve moved plants myself in every season of the year and I if you do it correctly and follow a few pointers you can mitigate the hazards of heat and dry,  cold and wet. The best time to do this is when conditions are as moderate as possible. That  is  mid-late spring and early to mid autumn. Or when temperatures fail to exceed 80ºF or drop below freezing. I like to move plants on an overcast day when its in the 40’s to 60’s- this is ideal if not practical with people’s schedules and lets be honest most people are active when its hot. So,  then pick the most moderate time of the day- early morning or late afternoon/evening to forestall too much shock.  I like to dig the new home hole first before I unearth the plant to be moved and this lessens the amount of time the plant spends twisting in the wind.  I fill that hole with water while I am unearthing the new tenant.  This will wet the soil column on all sides of the new hole and will tease the roots into fresh territory.

Some terminology that will help you along

“How big a rootball should I dig?” Is a query I get time and time again. The answer is that the live material you see above ground is often mimicked with the same amount of subterranean growth. A better way of envisioning this is to understand a plants drip line. That is the extent of its foliage- if you look directly down on a shrub for instance it would be the outer limits of where the shadow is cast or where water drips off the foliage.  The drip line gives you a fantastic cue about where to start digging around this line.  Another method, which I’ve used and does help is to pre-root prune a woody plant or vine.  Simply use your ditching shovel to slice directly down into about 1/3 of the way around the plants root mass-  slice gently going down at least 2′.  Ideally,  this should be done 2-3 weeks prior to moving. Its thought to put the plant into a more conservative mode- slowing growth and conserving energy. It puts the plant on notice.  This can be especially important when moving large shrubs.  Though prudent it isn’t always practical. So identify the drip line and you will understand how big of a rootball you will need to extricate.

Avoid shock with several different tactics

Use your shovel to cut around the drip line and insert the blade as deeply as possible. This should be done carefully and methodically. Once you have encircled the plant then go back and start to use the blade to insert and gently lift.  Distribute the leverage evenly around the plant. What you should not do is to grab the plant and pull. This will only lead to sadness.  Keep working the root ball with your blade gently easing it up out of the ground.  If you have to slice through  large roots then dig even deeper. Almost all plants have horizontal feeder roots that radiate out in a circle just below the soil surface. You want to retain as many roots as possible. Gently roll the plant out of the hole and transport it to the new site.  If the plant begins to wilt or if it is out of the ground a while and under stress I highly recommend pruning the top of the plant to equal the root mass.  Otherwise hose down the entire plant and make plans to keep it moist until installation. Notice where the plant wilts along the stem. Cut off  the wilted foliage. This will leave older hardened foliage that will survive the move more readily. And the plant will not waste energy rehydrating damaged tissue.  It should be said that deciduous plants should be moved in dormancy and this is best done in late winter prior to spring growth.

Settling in for a good life.

Dig your new hole about twice as large as the new rootball. This can seem like a lot of digging but it will ensure that your plant has stability and the resources to get up and start growing. Before you insert the new plant remember to fill the hole with water. Then set the new rootball in the water and carefully back fill with soil. This does three important things. It hydrates the plant, it wets the soil column below and alongside the hole directing root growth, and it settles the plant eliminating air pockets and ensuring stability.  Don’t be hesitant to stake unsturdy plants- recently planted things tend to wobble and a good windstorm can rock it and tear the roots. Adhere the plant firmly with gardening velcro to a sturdy piece of bamboo or rebar.  Then moving out from the trunk make a “moat” around the trunk about 1′ wide with a raised lip. This reservoir should be filled regularly to ensure that the roots grow happily directing the water straight down. To be honest there are very few woody or herbaceous plants that shouldn’t be watered frequently if the weather is hot. Under those circumstances you seriously cannot water too much for the first week. after watering its vital that you mulch with a material that will even out the soil moisture and mitigate temperature swings. Compost or fine bark mulches all work well. If you are planting into a gravel mulch  you can replace that when done which will also shade and protect the soil inhibiting moisture loss.

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Agaves require a long season to develop an extensive root system. Until this is developed the plant is much less hardy to cold. They are best planted/transplanted by mid- spring. The same can be true for semi-tender plants (zone 8).

Good to go

Pay careful attention to your recently moved plant.  If the season is right you should see new growth in several weeks. If your plant is anemic or yellow you might consider applying fertilizer at the time of the transplant. For broad leaved evergreens I find nothing superior to cotton seed meal (about 6.2.2). Simply dust several handfuls in the moat before you mulch. For perennials  I try to give a good handful of all purpose organic fertilizer (about 4.6.3). Its important to note that repeatedly moving young plants will cause so much stress that you could easily lose it to shock. Let plants develop a substantial root system before shifting them all over.   If you can only get a small root ball- you should consider cutting off as much of the top growth until you have an equal part roots to photosynthetic material.   The larger the rootball, attention to water, and mulch should have your plant established in no time. One last thought. Broad leaved evergreens that are moved from the shade to the sun can easily sunburn. Make plans to shield them from the hot sun with old pieces of screen or remay. The foliage should gradually acclimatize to the new light levels.

Finally

Summer 2017 (June, July, August – meteorological summer) was the second hottest recorded at PDX.  Records there have been kept since 1940- but even longer local records in context confirm it was an exceptionally hot year. This is surprising considering our hottest summer of all was just two years ago (2015) and 3 of the warmest summers of all time have occurred in this decade.  This scorching summer we topped 90º 24 times (average is 12) and we hit 100º three times (average is once at 100.3ºF) with 105ºF the warmest of all- a summit that has only been reached 10 other times in Portland recorded history.   We are anticipating a weak La Nina this winter which could mean quite a few things. I’ll wait to comment until new long range forecasts are out. Hopefully, there will be some consistency. Stay tuned.

Happy Gardening!

-Paul

You really move me

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.

 

 

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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.

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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.

-Paul

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.

zones

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.

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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.

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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.

-Paul

 

 

 

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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.

olive
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.

Thanks,

-Paul

Plant triage after a wild winter

HOLY MOLY GET THE COLD OUT

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.

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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.

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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.

-Paul

January 18, 2017

HOLY MOLY GET THE COLD OUT

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’

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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’

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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’

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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

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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’

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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!

-Paul

 

 

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