Forestfarm
Colvos Creek
Cistus

have sold it. Who has some for sale today I can't say. All of the above do have web sites with availability information.

I planted one on Camano Island that grew up, bloomed and then froze out all in a few years. However, a Seattle garden I know of probably still has one, it came through the same winter without serious difficulty.

Thanks. I tried those, no luck. Baileyana, pravissima and dealbata are what I have seen the most of. Maybe boormanii isn't quite hardy enough for the nw and thats why it's not available.

I'm not quite sure but if we are talking about a certain Ms. S. M. her A. boormanii (and the big A. pravissima, sadly) were severely damaged in this year's Feb freeze. She got to 20F. Of course, they were all in bud and just starting new growth. Last I heard, she was going to give them the axe.

A. boormanii is at least as hardy as A. baileyana, but I would rank it a little less hardy than A. pravissima or A. dealbata on average. I'm starting to think Acacias here are not really worth it at all unless you start with a known provenance of superior hardiness (e.g. A. dealbata var. subalpina). Even more so than most Southern Hemisphere plants... they really hate cold, dessicating winds with low humidity when the cold air comes.

Well thats kind of discouraging. I guess the good news is I can't find any anyway. I had struck upon boormanii because I saw a mention of it online as being tolerant of winter wet and summer dry-but you are saying it's the cold winter wind, not the winter wet that is the problem. Maybe I could cover it with a clear plastic tarp for that one cold week each year!

Now I am interested in Acacia Vestita, which, unfortunately, I am able to find.

I also came across Arthur Lee Jacobson's article on Wattle. He suggests planting in a drier spot to avoid overly rapid new growth that may be less cold hardy. And to expect a winter sometime that kills it.

Same location, not surprised the other species eventually went as well. Had that one on Camano, too, grew taller than house before burning up. Ian should try to get a look at the Washington Park Arboretum files of plants that have been tried there over the decades. Centuries of gardening experience in UK to learn from, too, recorded in comparatively abundantly produced British gardening books and periodicals. There is always scope for individuals to break new ground, building on the findings of the vast number of people who have come before rather than ignoring them.

The more similar a site is to plant's habitat, the more likely success. Arctic fronts do not occur in southern hemisphere. And each plant has a minimum temperature below which even a few hours of exposure is lethal.

TREES OF SEATTLE - SECOND EDITION (2006, Arthur Lee Jacobson:

"Perhaps two dozen species (of over 1,200!) of Acacia have been tried here over the years, chiefly at the Arboretum and the U.W. campus. Though they grow rapidly, very cold winters here kill them, so they seldom attain much size--but some resprout from their roots."

Same reference gives descriptions and locations of examples of AA. baileyana, dealbata, longifolia, pravissima, retinodes and rubida. However, two of these were the ones Ian said are gone, so others mentioned may also have failed already.

Well she said she was going to chop them, I'm not sure if she actually did it. I need to visit her again, as well as take a day to poke around Seattle and see what survived the winter in the euc and Acacia department. I am especially curious about all the Acacias since they seem to hate dessicating winds even more than eucs. I should also check out the E. globulus specimens. I did not lose any Acacias from my garden in Olympia last winter, including all aforementioned species except baileyana (I don't have it).

I've seen very little damage.

Well, this weekend I bought two a. vestita and an a. pravissima, 5 dollars each. If it gets really cold this winter I will be out 15 bucks. I can live with that.

I'm thinking of putting the pravissima in a big pot for now. I planted the vestita on a slope next to my driveway on the SE corner of the property. What about putting plastic tarp over the roots to keep them drier in the winter?

I hope you're not out in Maltby, that is too far out for acacias.

The Australian Acacias should not be kept dry in winter - in general, they like moisture. Here is an idea. When those cold winds come along (and they WILL come, and freeze-dry your plant one of these years), get out your garden hose and spray the plant until the entire thing is covered in a nice coating of ice. That way the leaves will be protected from the dessicating cold winds. I am completely serious... try it as an experiment anyways!

Not in Maltby. Madison Valley, slope facing east, not too far from the Arboretum.

Ian, have you actually tried this technique? What about a screen of clear plastic around it to block these dessicating cold winds. And should I be watching the weather report looking for a certain minimum wind chill factor?

You'll likely have problems down there that sites higher up and farther west won't. Notice that the Arboretum has most such plants (gums, New Zealand collection, anything that won't like a frost pocket or soggy soil) on the ridge, around Arboretum Drive and in other more elevated portions of the park. As it happens up and down east shore of central Puget Sound there is a tendency for the Banana Belt to be west of I-5, with districts east of it to have lower temperatures. With its low-lying areas the Arboretum gets readings below 10 degrees F. when there is a cold winter.

East exposure can also be a problem for borderline plants, as the sun may hit them early in the day while still frozen. It depends on the specific attributes of the planting site. If you are planting these in warm sandy soil, in hot pockets against south-facing walls where cold winds are cut by a building right behind and frosty air does not pool you may have great results--as long as the minimum winter temperatures stay high enough.

Since they are nearly all tender it might actually be more rewarding to go for the showy ones like Acacia baileyana and just expect to be replacing them periodically. Buying direct from growers like Colvos Creek or others who stock small sizes, such as forestfarm you can get comparatively inexpensive small starts, as required (and when available). Or try ordering seed and growing your own.

Here is a link that might be useful: Desert Northwest

Dang, wrong side of 1-5. But while close to the Arboretum I am higher up. The two I planted are not in a frost pocket. I'm treating this as an experiment, I know these are tender plants, I'm just trying to find out if there is anyway to improve my odds.

The replace every few years strategy suggests going with the fastest grower. But then what if you have several mild years in a row and your Dealbata is growing like crazy in a space where you only wanted a big bush.

The mention of soggy roots again makes me wonder about trying to keep the roots drier. While it might like the moist soil, maybe the drier soil slows newer and more tender growth as Arthur Lee Jacobson suggested.

More like every few decades, if you are lucky. Probably won't have that level of success, but every few years would be kind of ridiculous. Might as well plant herbaceous annuals.

No, I haven't actually tried this - it's just an idea. Plants cannot "feel" or suffer from wind chill in the way that people do. The thing that really gets the Acacias and certain other Southern Hemisphere plants (many of them really, and some more than others) is the combination of wind, subfreezing temperatures and low humidity. Anytime we have east winds bringing modified arctic air into the region, you will notice the humidity drops way off to about 10-20% (except in the most maritime of locales, such as Port Townsend). In this situation, the plant is severely stressed because
- air movement has a dessicating effect
- super low humidity has a dessicating effect
- being below freezing is obviously an additional stress.
These Acacias etc. do endure very cold temperatures in the wild, in some cases down to 10F, 0F or even below. But whenever they have severe frost in the wild it is always with 100% humidity and no wind.
So that is why I like my ice idea, even though I have never tried it. Sure the plants will be cold but there will be no chance of them getting dessicated. It is just that though, an idea. If you can trap humidity with plastic, that might work, until the plant gets too large. But you will have to seal it off pretty well for that to work!

As far as 'drier soil' we could be talking about a couple of different things.
#1 For many plants, there is an advantage to allowing them to dry out in late summer so they will harden off instead of growing into the fall, which would leave them susceptible to freeze damage. Such plants can still be rained on all winter and watered and fed generously in spring with no problems, as long as you stop in summer.
#2 Many alpines, xeric plants, some western natives etc. show greater cold hardiness if the soil is really gritty so that it does not collect moisture in winter (better yet, a rain cover may be beneficial for some). But they too usually like to be watered generously in the spring.

I would put Acacia and most cold hardy Aussie plants in category #1. Growing them a little tough is great...we don't need to water everything all summer around here.... growing them too tough might slow them down more than necessary.

Plants going into winter with a water deficit are disadvantaged. The winter dampness issue here may be mainly one of fungal decay, in many instances. Spraying with water at the point of freezing to protect from deep cold has been used for years in agriculture. You have to get the timing right.