Not as hardy as windmill palm. Even that one may be damaged by 10 degrees F.

My neighbors bought a big one last year, looks like with the mild winter it might barely make it this time. Too bad really, because it's only delaying the inevitable. No realistic chance of long term survival here in Marysville.

One as close as possible to the water froze to the ground in 1990 at the government locks in Ballard. But sprouts appeared afterward and I think the specimen may be back up to where it was before that hard winter - or perhaps bigger. I have not looked for it for awhile.

I tried the grayish form on Camano Island several years ago, it did not last.

There is much variation in minimum temperatures on different sites in the region, how cold your particular garden gets is critical to whether or not a specific plant is "hardy here".

Thank you both for the feedbacks, althought discouraging:-)
The reason I bought them because last year I had a few small ones planted in the ground in Auburn and they all survive our mild winter (the lowest I got was about 14 F for one or two nights-I think). I think I'll put these in pots and try to move or cover them somehow.

Sunset Western Garden Book (2007, Sunset Publishing Corporation, Menlo Park) says

Probably one of hardiest palms; has survived brief (but not prolonged) temperature drops to 0F/-18C or a bit lower

That was likely in a hot climate on a warm soil. Hot climate plants may often not be so tolerant under our conditions.

Thanks bboy. Maybe I should tryp needle palm or sabal huh?

The only one you see around here as a long-established, persisting landscape feature is windmill palm. That one sometimes even re-seeds.

bboy, do you know of any Trachycarpus wagnerianus (T wagneriensis) that have persisted in the area? I have a small one in my Edmonds garden.

The outside of the greenhouse at the state capital campus has been attended by one for years (I assume it is still there). Searching "wagnerianus olympia" or something like that will probably bring it up. Also try "northwest palms" or maybe "pacific northwest palms" for ample photos and discussion - there are groups with an internet presence that are devoted to growing of palms here and related topics.

I saw the Trachycarpus wagnerianus at the state capital campus greenhouse in 1962. It was about four or five feet tall then. So it has been through some very cold events.

I understand that the state is removing the greenhouse and will get rid of that palm tree. I hope they just move it, not cut it down.

Maybe a letter writing campaign is in order. Since palms are not hard to move, as far as it goes and the tree is not huge it would be quite a shame if somebody just cuts down what pretty much amounts to a heritage specimen at this point.

I also planted a small waggie last year along with a Takil. So far waggie is doing well but Takil lost the spear (still green though). But we all know that last winter wasn't that bad.

There are examples of long term Chamaerops humilis in the PNW in Seattle, Victoria Salt Spring Island, Portland, etc. Yes, they can get damaged in a bad winter, and do greatly benefit from a hot, dryer in winter site, to give them the best chance of surviving the periodic bad winter. I'd suggest that they can be just as hardy as Trachycarpus fortunei in surviving occasional freezes down to about 20F, but will greatly benefit from being sheltered from excessive wet in combination with cold temperatures, and stringing old fashioned Xmas lights amongst the foliage and a protective tarp overhead will minimize damage. As they are slow growing to make any height, they can more easily be protected when you know a bad freeze is coming. They also make great container plants, and can be left indefinitely in a half oak wine barrel sized container that could be wheeled into an unheated garage during a bad freeze event. They easily handle cold down to 25F without need of special measures, and it is alleged that the silver form C. humilis v. cerifera may be marginally hardier.

If the idea of siting one of these to best suit it given PNW wet winters sounds like too much work, stick to growing it as a movable container plant. It is documented both in the USA and Europe that this palm can survive temps down to 5F, but yes, they are more reliable where it doesn't usually get this cold, and winters seldom get this cold and temps rise back up during the day.

Chamaerops humilis, along with Butea capitata and Trachycarpus fortunei have proven to be among the more durable palms for the PNW, but will definitely perform better if one doesn't expect them to fend for themselves in a severe freeze. I would add Jubaea chilensis, Brahea armata and Brahea 'Clara' to this list of palms if one is also willing to protect them occasionally. Personally, I would tend to think they are worth the bother if one likes the look of these palms, and is willing to accommodate their needs in a bad winter. It is also important to realize that micro-siting for perfect winter drainage, and knowing that freezing rain can also damage foliage are important considerations to remember with growing palms in the PNW.

Also, it would be important to remember that container grown palms left in pots outdoors may get frozen roots at temperatures which the same palm will easily tolerate if it were in the ground, and plan accordingly.

Thanks bahia for the information and suggestions. I'll try to protect them as much as possible during winters.