What is your favorite cold hardy palm?

[Fukuoka Scott]

6 hours ago, PricklyPearSATC said:

I am not much of  a Washingtonia fan....

I see what you did there 

[Fukuoka Scott]

9 hours ago, PalmatierMeg said:

Sabal palmetto 'Lisa', hands down.

Oh yeah wow, those look amazing!

[Swolte]

I was going to go with the Jubaea but I figured the palm is too unpragmatic due to its slow growth and ailments in Central Texas (due to humidity/heat and/or nematodes) . Next in line would be the Canary Island Date Palm! I mean, who doesn't!! It's got that majestic, tropical look and the name alone sounds like a tropical destination. Can't believe we can actually grow them in College Station and that most mature ones survived the recent historic freeze event.   

(pic from interwebs)

[teddytn]

47 minutes ago, Fukuoka Scott said:

Hey, my howeas have survived multiple freezes and even being covered with snow for extended periods.  (But yeah don't plant 'em if your lows get below 28F very often)

That would be a cool pic to see howeas covered in snow! No you’re right though, it’s all perspective. For me saying a Bismarckia is a cold hardy palm is laughable. You can pretty much count on one hand the palms that will survive in my yard. Lol

[palmsOrl]

10 hours ago, PalmatierMeg said:

Sabal palmetto 'Lisa', hands down.

I agree with this choice, very appealing look imo.  Almost remind me of Pritchardia.

[UK_Palms]

I like Washingtonia Filifera, but it simply has to be CIDP for me. They're big, majestic palms and provide instant impact. Very tolerant of cool, wet conditions as well. By far the best looking and most exotic palm for London these days... in fact it's not even close with anything else... 

[SLTX21]

On 5/11/2021 at 5:56 PM, Fukuoka Scott said:

I suppose this is more of a "cool hardy" palm since they can only take low 30s/upper 20s for short periods, but I gotta say Howea forsteriana. Look at the look they give a garden in Southern California.

For actual cold hardy palms I'd say Syagrus romanzoffiana, and for palms that take truly severe cold under 20F, the choices are limited but probably Butia odorata. 

Howea fosteriana? So that is what they are. They look VERY similar to Coconuts to the average person.  They seem to have similar hardiness to royals. Have they tried to grow this in the Rio Grande Valley? I'm thinking that could give a coconut look that may actually have a chance for survival vs. an actual coconut.

[Fukuoka Scott]

2 hours ago, SLTX21 said:

Howea fosteriana? So that is what they are. They look VERY similar to Coconuts to the average person.  They seem to have similar hardiness to royals. Have they tried to grow this in the Rio Grande Valley? I'm thinking that could give a coconut look that may actually have a chance for survival vs. an actual coconut.

There are some very healthy specimens in Orlando so they can take some heat and cold, so I think they would be doable in the RGV *IF* planted under a dappled shade canopy (because the RGV is hotter than Orlando and they sulk in hot full sun) and they would need protection with temps below 29F. I know the RGV goes way below that but not very often so should be feasible...

[Ryland]

Brahea armata... but this is an impossible choice.  I might have a different answer next week.

[teddytn]

Since nobody threw it out there I will. Nannorrhops ritchiana has to make the list. I wish I had pictures. Saw these in habitat In Kowst, Afghanistan. The high desert gets hot, but better believe it gets cold too in the winter. I really can’t remember it ever raining in the winters. Cant see it taking wet winters well.

[Xenon]

10 hours ago, SLTX21 said:

Howea fosteriana? So that is what they are. They look VERY similar to Coconuts to the average person.  They seem to have similar hardiness to royals. Have they tried to grow this in the Rio Grande Valley? I'm thinking that could give a coconut look that may actually have a chance for survival vs. an actual coconut.

There are/were 20+ year old unprotected coconuts in the RGV that have set viable fruit many times before. 

Attalea and "coconut queens" (Syagrus schizophylla x romanzoffiana) are much better options for RGV than Howea. Beccariophoenix grows well in the climate but doesn't like the hard irrigation water. 

[Paradise Found]

My choice, any mule palm and Chamaerops humilis var. cerifera looks awesome when bigger. 

[Collectorpalms]

11 minutes ago, Paradise Found said:

My choice, any mule palm and Chamaerops humilis var. cerifera looks awesome when bigger. 

Because All my Mules died from the freeze including the ones I wrapped extensively, I have removed them from my “cold hardy” definition unfortunately.

Cerifera did survive. It’s a winner, but more of a team player. A CIDP or a Washingtonia Filifera, are still the dominate specimen palms, so they come first.

[Paradise Found]

34 minutes ago, Collectorpalms said:

Because All my Mules died from the freeze including the ones I wrapped extensively, I have removed them from my “cold hardy” definition unfortunately.

Cerifera did survive. It’s a winner, but more of a team player. A CIDP or a Washingtonia Filifera, are still the dominate specimen palms, so they come first.

Sorry to hear about your mules dying.  My are not long term in my garden but they keep trekking on.  My Cerifera  is looking pretty good planted in 2004. Leaves are over my head.  

CIDP and W Filifera Doesn't like my rain and cooler temps in winter....But I haven't tried one either. LOL. 

[UK_Palms]

30 minutes ago, Paradise Found said:

CIDP and W Filifera Doesn't like my rain and cooler temps in winter....But I haven't tried one either. LOL. 

Places like Portland and Seattle are no colder or wetter than London during winter, so I don't get why CIDP and Filifera won't make it there. In fact they get more sunshine hours too. You would think those parts of the PNW would have some big CIDP's and Washies, especially in the inner city areas where the UHI is greatest. So it doesn't really make sense.

London is jam packed with CIDP's now that are getting pretty big and there's quite a few 30+ foot Filifera's now, so I don't really buy the "too much wet-cold" argument. There must be another factor in survival that is being overlooked as well, surely. Why would they survive in London but not Portland? Perhaps there are some decent sized ones tucked away in Portland or Seattle back yards, maybe? Out of sight and up against a house for instance...?

[atlamtapalms]

1 hour ago, Collectorpalms said:

Because All my Mules died from the freeze including the ones I wrapped extensively, I have removed them from my “cold hardy” definition unfortunately.

Cerifera did survive. It’s a winner, but more of a team player. A CIDP or a Washingtonia Filifera, are still the dominate specimen palms, so they come first.

Can you remind us of your ultimate lows and your sustained lows? How are your Filifera? Was it a wet cold at your place? I always wondered how Filifera handles frozen ice and cold rain and snow. I know dry cold it does well enough.

Edited May 13, 2021 by atlamtapalms

[Collectorpalms]

Just now, atlamtapalms said:

Can you remind us of your ultimate lows and your sustained lows?

I had 7 days at or below 32F, 6-8 inches of drifting snow. 1 inch of ice and a low of 4*F.

it was a 126 year record cold week. Nothing even compared since 1895.

[EastCanadaTropicals]

4 hours ago, teddytn said:

Since nobody threw it out there I will. Nannorrhops ritchiana has to make the list. I wish I had pictures. Saw these in habitat In Kowst, Afghanistan. The high desert gets hot, but better believe it gets cold too in the winter. I really can’t remember it ever raining in the winters. Cant see it taking wet winters well.

Forgot about that one, love Nannorrhops

[atlamtapalms]

17 minutes ago, Collectorpalms said:

I had 7 days at or below 32F, 6-8 inches of drifting snow. 1 inch of ice and a low of 4*F.

it was a 126 year record cold week. Nothing even compared since 1895.

I would say any true survivors are what we would call cold hardy for sure. That should be the new standard for hardiness.

[teddytn]

25 minutes ago, Collectorpalms said:

I had 7 days at or below 32F, 6-8 inches of drifting snow. 1 inch of ice and a low of 4*F.

it was a 126 year record cold week. Nothing even compared since 1895.

That is every year winter weather where I’m at

[Collectorpalms]

2 minutes ago, atlamtapalms said:

I would say any true survivors are what we would call cold hardy for sure. That should be the new standard for hardiness.

Certainly. Also I had a lot of wind, the windchill was -8*F/ -22*C. 
Wind shelter definitely plays a key to survival. Regardless of the thought that plants don’t feel windchill is, was just proven wrong by all my pictures of survivors next to buildings and dead ones away from the buildings.

[Trustandi]

@UK_Palms I would say the reason why is their availability for sale and sizes in PNW. I have never seen any CIDP for sale at big box stores. Washingtonia filibustas are usually available for sale but most of the times  they are in 1g or 5g sizes. If we get nasty winters, they are finished and cannot recover. 

 

[Collectorpalms]

10 minutes ago, teddytn said:

That is every year winter weather where I’m at

I am originally from southern Indiana. It’s not like that every year. I also went to College along Lake Superior. So I understand cold.
But we also don’t grow Alberta or Colorado spruce trees. A ton of other plants are dead or killed to the ground, 100+ year old southern live oak trees are dead. Native Texas Mountain Laurel was killed back or defoliated etc...

Texas native Yucca Rostrata which is hardy to zone 5 into Denver, Colorado, I lost all my smaller ones.

Edited May 13, 2021 by Collectorpalms

[Collectorpalms]

26 minutes ago, EastCanadaTropicals said:

Forgot about that one, love Nannorrhops

Palm gets Way to out of control for me, but ok if You have land or a botanical garden. It did somewhat live, if you consider it being defoliated and many trunks killed, about as cold hardy as Serenoa Repens Silver. But it is NOT more cold hardy that Serenoa.

[Collectorpalms]

5 hours ago, teddytn said:

Since nobody threw it out there I will. Nannorrhops ritchiana has to make the list. I wish I had pictures. Saw these in habitat In Kowst, Afghanistan. The high desert gets hot, but better believe it gets cold too in the winter. I really can’t remember it ever raining in the winters. Cant see it taking wet winters well.

Here is how Nannorrhops faired.

Edited May 13, 2021 by Collectorpalms

[Chester B]

51 minutes ago, UK_Palms said:

Places like Portland and Seattle are no colder or wetter than London during winter, so I don't get why CIDP and Filifera won't make it there. In fact they get more sunshine hours too. You would think those parts of the PNW would have some big CIDP's and Washies, especially in the inner city areas where the UHI is greatest. So it doesn't really make sense.

London is jam packed with CIDP's now that are getting pretty big and there's quite a few 30+ foot Filifera's now, so I don't really buy the "too much wet-cold" argument. There must be another factor in survival that is being overlooked as well, surely. Why would they survive in London but not Portland? Perhaps there are some decent sized ones tucked away in Portland or Seattle back yards, maybe? Out of sight and up against a house for instance...?

I don't know what to tell you except the proof is in the pudding.  You have to be in zone 9B to start seeing them, and many of those areas get double the rainfall we do.  Now I would think down in southern Oregon in the really hot and dry spots like Medford the Washingtonia will survive (in fact I know they do) and maybe CIDP.  Portland is not a very big city so the UHI is minimal, I do know of a few spots along the Willamette river that are rated zone 9A due to UHI and the water mass.  However you will not find anything aside from the "bog standard" palms or plants in those areas.  The Cordylines tend to get more mature in those spots, whereas my area every 10 years or so they get knocked back so I don't see them much above 10' tall.

[Collectorpalms]

15 minutes ago, Chester B said:

I don't know what to tell you except the proof is in the pudding.  You have to be in zone 9B to start seeing them, and many of those areas get double the rainfall we do.  Now I would think down in southern Oregon in the really hot and dry spots like Medford the Washingtonia will survive (in fact I know they do) and maybe CIDP.  Portland is not a very big city so the UHI is minimal, I do know of a few spots along the Willamette river that are rated zone 9A due to UHI and the water mass.  However you will not find anything aside from the "bog standard" palms or plants in those areas.  The Cordylines tend to get more mature in those spots, whereas my area every 10 years or so they get knocked back so I don't see them much above 10' tall.

Seattle (Skagit Valley) and parts of the Netherlands (Holland) are most similar in average temperatures. I know this because they are two largest areas of tulip growing that have to have perfect weather for tulip agriculture.

I have seen trachycapus in the Netherlands, but not seen much else?

Edited May 13, 2021 by Collectorpalms

[teddytn]

25 minutes ago, Collectorpalms said:

I am originally from southern Indiana. It’s not like that every year. I also went to College along Lake Superior. So I understand cold.
But we also don’t grow Alberta or Colorado spruce trees. A ton of other plants are dead or killed to the ground, 100+ year old southern live oak trees are dead. Native Texas Mountain Laurel was killed back or defoliated etc...

Texas native Yucca Rostrata which is hardy to zone 5 into Denver, Colorado, I lost all my smaller ones.

No for sure terrible. The same thing could happen to any of us 

 

34 minutes ago, Collectorpalms said:

I am originally from southern Indiana. It’s not like that every year. I also went to College along Lake Superior. So I understand cold.
But we also don’t grow Alberta or Colorado spruce trees. A ton of other plants are dead or killed to the ground, 100+ year old southern live oak trees are dead. Native Texas Mountain Laurel was killed back or defoliated etc...

Texas native Yucca Rostrata which is hardy to zone 5 into Denver, Colorado, I lost all my smaller ones.

No for sure for Texas just worst case possible. Sorry to you and everyone else that lost plants. But here in northern middle TN the weather you described is normal every year winter weather. Same, I’m originally from upstate New York that weather would be a mild winter there. What surprises me is all the native plants and palms that didn’t make it like you say, that’s very weird. If Mother Nature planted it, should be rock solid in that location. Must have been way worse than I can imagine. Sorry again really. 

[teddytn]

41 minutes ago, Collectorpalms said:

Palm gets Way to out of control for me, but ok if You have land or a botanical garden. It did somewhat live, if you consider it being defoliated and many trunks killed, about as cold hardy as Serenoa Repens Silver. But it is NOT more cold hardy that Serenoa.

Spot on there, just looked up average cold in Afghanistan where I saw them. Average low 32f so arguably may see 20f on a cold year. No where near 4f where you were. And that 32f is bone dry. 

[UK_Palms]

21 minutes ago, Trustandi said:

@UK_Palms I would say the reason why is their availability for sale and sizes in PNW. I have never seen any CIDP for sale at big box stores. Washingtonia filibustas are usually available for sale but most of the times  they are in 1g or 5g sizes. If we get nasty winters, they are finished and cannot recover. 

 

Smaller size washingtonia are a bit of a problem in general when growing in marginal climates. I have problems with them here. Even in London, some of the smaller ones look a bit rough during their younger years, but once they get to a decent size and become fully established, they become stronger, hardier and replace damage much quicker. Where I am out in the countryside with no UHI effect, Filifera or hybrids are my only option really. It's a case of protecting while young until they get to a decent size. Even then I am still only just about 9a here. I have an 8b winter every 3 years. Whereas central and eastern London has been a solid 10a zone in 2 out of the past 3 winters, which may explain why CIDP and Washies are doing so well.

I reckon if you scout out Portland on google maps though, using the aerial photo imagery, you will find some decent sized CIDP and Washies in people's front and back yards. If they are within the city's UHI, protected while small, planted close to a house and south facing, surely some will make it there. Portland is 9b right? Also London gets a lot of rain during winter, just like the PNW. It's definitely wetter in winter nowadays, compared to what the long-term stats show. At least one winter month in London will have 5-6 inches of rain. Yet Filifera's don't seem to have a problem with the wet-cold, at least once they are a decent size anyway. I'm actually surprised how well the big ones handle the wet-cold here. Not a spec of damage after winter when big Trachycarpus Fortunei look like crap, all yellow with tatty leaves. Yet the big Filifera's stay green and retain an impressive crown. 

[Palmensammler]

For me the only hardy ones are Trachies, Needles and Sabal minor. Nannorhops dies here even during a normal winter because of the high humidity. Even Chamaerops wouldn't survive a strong winter.

Eckhard 

[Ryland]

31 minutes ago, UK_Palms said:

Smaller size washingtonia are a bit of a problem in general when growing in marginal climates. I have problems with them here. Even in London, some of the smaller ones look a bit rough during their younger years, but once they get to a decent size and become fully established, they become stronger, hardier and replace damage much quicker. Where I am out in the countryside with no UHI effect, Filifera or hybrids are my only option really. It's a case of protecting while young until they get to a decent size. Even then I am still only just about 9a here. I have an 8b winter every 3 years. Whereas central and eastern London has been a solid 10a zone in 2 out of the past 3 winters, which may explain why CIDP and Washies are doing so well.

I reckon if you scout out Portland on google maps though, using the aerial photo imagery, you will find some decent sized CIDP and Washies in people's front and back yards. If they are within the city's UHI, protected while small, planted close to a house and south facing, surely some will make it there. Portland is 9b right? Also London gets a lot of rain during winter, just like the PNW. It's definitely wetter in winter nowadays, compared to what the long-term stats show. At least one winter month in London will have 5-6 inches of rain. Yet Filifera's don't seem to have a problem with the wet-cold, at least once they are a decent size anyway. I'm actually surprised how well the big ones handle the wet-cold here. Not a spec of damage after winter when big Trachycarpus Fortunei look like crap, all yellow with tatty leaves. Yet the big Filifera's stay green and retain an impressive crown. 

I think there are a few factors which give London a slight edge, beyond just availability of the plants.  Firstly European cities and especially English cities are much more dense than American cities - especially those in the US West.  Through most of London you have miles and miles of terraced houses close together, whereas even in central parts of Portland, like where my uncle lives, the detached house still rules.  I think this significantly greater density could result in a stronger moderating effect on the climate in London.

Another factor is the continent - where Portland, Seattle and Vancouver do generally benefit from strong moderating Pacific influence, but every now and then something nasty comes out of the interior.  Portland, as @Chester B knows, can get bad ice storms which we simply don't have here in the UK.  Vancouver gets some occasional bad cold events coming down the Fraser Valley.  On a side note I remember taking a ridiculous fall in the street trying to walk on half an inch of ice in Portland about 15 years ago .  Portland could perhaps be considered a 9a climate normally, but it gets a wild winter event every now and then that is anything but (in southern Oregon there was a 7a winter as recently as 2013, I'd have thought Portland may have had 8a type temperatures?).  When we get bad cold events here it tends to be a half-zone type thing - e.g. the "Beast from the East" could only deliver a 9a winter to Manchester, the coldest since the all-time record low was set in 2010 (8a for Manchester).  Continental cold events have to cross the sea first to get here, which means they aren't as bad.

Also, and I don't know whether it makes a difference, the PNW is definitely wetter in Winter.  Portland gets twice as much rain as London, and it's heavily tilted towards winter.  Some parts of Washington/BC are in the Olympic rain shadow, which may help for palms.  I really like Port Townsend - perfect climate in my opinion, and smack in the centre of the rain shadow with lots of oceanic moderation but far enough from the Pacific to get warm in summer.

That being said there are plenty of cold hardy palms that will thrive there so there is still much to celebrate!  I generally assume that as far as cold is concerned, if it can be grown in Seattle I can probably grow it in Manchester .  When it comes to palms that need heat though, PNW is probably better... for instance I would never be able to grow a Sabal.  Maybe they'd be ok in London.  Back to choice cold-hardy palms, there's a surprising amount of choice!  Some of the Sabal picture posted in this thread are lovely by the way.

[Collectorpalms]

You can grow a CIDP in Seattle. Evidently there are just not enough factors that allow them enough years to get big. Here all the big ones Survived, but small ones did not.

January 1950 Seattle must been one to remember. Doubt they had many Palms at that time to kill. As a meteorologist I can’t think of any cities breaking that many record cold days in a row. However, in Texas we break heat records in a row.

Edited May 13, 2021 by Collectorpalms

[UK_Palms]

1 hour ago, Collectorpalms said:

Seattle (Skagit Valley) and parts of the Netherlands (Holland) are most similar in average temperatures. I know this because they are two largest areas of tulip growing that have to have perfect weather for tulip agriculture.

I have seen trachycapus in the Netherlands, but not seen much else?

Northern Europe got hit pretty hard this winter just gone. Two separate Arctic/Siberian storms in January and February. London and the UK experienced its coldest January in 11 years. London also had its 4th ever coldest winter in terms of daytime highs. It was pretty cold here. The European continent got hit even worse, especially in Scandinavia and eastern Europe.

Since the UK is an island, the sea acts as a buffer against the big arctic or Siberian air masses, mitigating the degree of cold. Places like France, Netherlands, Germany etc don't benefit from that and are sometimes in the direct path of Arctic or Siberian air masses that come across the continent from the northeast. Any CIDP or Washies that are unprotected in the Netherlands will almost certainly get wiped out during these "Beast from the East' events.

I know some growers in the Netherlands had to frantically protect their palms, including a fairly large CIDP in a coastal spot. I'm not sure whether it survived. Sadly, an entire field of Washie's were lost as well near Amsterdam. Axel posted this photo a few months back...

According to Wunderground...

Berlin, Germany was below freezing for 11 days/nights and went down to 3F. 

Amsterdam, Netherlands was below freezing for about 8-9 consecutive days/nights and went down to 13F. 

Paris, France was below freezing for 7 consecutive days/nights, but the lowest was only 18F.

London was below freezing for 2 consecutive/days nights but only went down to about 25F in central and eastern London (Robusta and robusta-dominant hybrids aren't burned there). 

[Swolte]

8 minutes ago, UK_Palms said:

Sadly, an entire field of Washie's were lost as well near Amsterdam. Axel posted this photo a few months back...

Oh man, that's a pity. I have lived in Amsterdam for several years and that would have been a sight to behold.  

[UK_Palms]

4 minutes ago, Swolte said:

Oh man, that's a pity. I have lived in Amsterdam for several years and that would have been a sight to behold.  

I think they were near Amsterdam, but Axel would have to clarify. It may have been The Hague or Rotterdam?

Unbelievably, they have already replanted that same field with new washies of equal size I think lol! I appreciate their efforts, but you fear the worst for those ones too... 

[Chester B]

Portland is zone 8B, there are no Washies or CIDP's lurking in people's yards.  Trust me I would have seen them and know many of the people doing the tropical thing.  There are lots of bloggers, and social media presences of prominent gardeners as gardening is a pretty big thing out this way.  Most palm people I speak with will say every 10 years the Butias and Jubaeas will be killed.  I haven't seen a winter that cold but 2016 was pretty brutal - I sure hope it doesn't happen again.

Washies are sold by the hundreds here every year at Home Depot, I even have one myself in a pot.   Trialing it outside, all that happens is it gets black fungus that destroys the fronds and starts attacking the spear, even under cover it still takes some sort of damage I guess from the humidity?   Find one that's been in the ground for at least 5 years.  It just doesn't happen without some protection, I'm not going to be delusional as to what we can grow.  The one nursery has a pretty mature CIDP, bigger than a car and it gets protected every year with a huge greenhouse structure with heat.  Here's a video I shot this year of it.  Over 20' to the top of that.

Our combination of constant wet with our cooler temperature will kill Washies and CIDP's, its accepted by the people who own the palm nurseries around here.  Now Sabals are not an issue, we can grow them.

 

 

[Swolte]

1 hour ago, UK_Palms said:

I think they were near Amsterdam, but Axel would have to clarify. It may have been The Hague or Rotterdam?

Unbelievably, they have already replanted that same field with new washies of equal size I think lol! I appreciate their efforts, but you fear the worst for those ones too... 

How unlike the Dutch, who literally built a country by defying the elements, to let something like that happen! (Build a dyke around it!* ).

Having some 'Windmolen' palms may be fitting, though!


(I am Dutch, hence the puns!)

[Ryland]

8 hours ago, Chester B said:

Portland is zone 8B, there are no Washies or CIDP's lurking in people's yards.  Trust me I would have seen them and know many of the people doing the tropical thing.  There are lots of bloggers, and social media presences of prominent gardeners as gardening is a pretty big thing out this way.  Most palm people I speak with will say every 10 years the Butias and Jubaeas will be killed.  I haven't seen a winter that cold but 2016 was pretty brutal - I sure hope it doesn't happen again.

Washies are sold by the hundreds here every year at Home Depot, I even have one myself in a pot.   Trialing it outside, all that happens is it gets black fungus that destroys the fronds and starts attacking the spear, even under cover it still takes some sort of damage I guess from the humidity?   Find one that's been in the ground for at least 5 years.  It just doesn't happen without some protection, I'm not going to be delusional as to what we can grow.  The one nursery has a pretty mature CIDP, bigger than a car and it gets protected every year with a huge greenhouse structure with heat.  Here's a video I shot this year of it.  Over 20' to the top of that.

Our combination of constant wet with our cooler temperature will kill Washies and CIDP's, its accepted by the people who own the palm nurseries around here.  Now Sabals are not an issue, we can grow them.

 

 

This is sort of what I expected - despite the temperature profile looking like it should be possible to get away with a CIDP there are other factors that limit their long-term chances.  Knowing me, I might try anyway if I was living there!  Given the perfect sheltered position of course.  I know some success has been made of them on some Puget Sound islands but not sure whether those are still going, whether they can make it long term.

Is that big one in the video at Raintree Tropical?

I think you are right in that CIDP and Washingtonia are marginally possible in the Rogue Valley - but when it gets really cold it will get colder there than Portland, which is the main limiting factor.  There used to be some nice Washingtonias in Roseburg, which is perhaps the best of both worlds climate, between the Rogue and Willamette valleys.  Phoenix canariensis is one of my favourite cold hardy palms - has been since I was about 13 - so I would probably attempt it anywhere I thought I had a half chance.  We didn't succeed in the Rogue Valley though (young Phoenix theophrasti doing ok though).  If unable to grow a Phoenix I would certainly by trying Jubaea though!  That is a marvellous and very hardy palm

[UK_Palms]

What about Phoenix Theophrasti in the PNW? Are they worth a try there? It supposedly takes the wet-cold just as well as CIDP and is slightly more cold hardy. Supposedly. I know they are just a rarer palm in general though and harder to come by, so maybe they haven’t been adequately trialled in places like the PNW and southern England. There is definitely some potential there though. 
 

I’m actually surprised how well Peter Jenkins Theophrasti is doing out near Heathrow airport. The western suburbs are the coldest and wettest part of London during winter, yet his Theophrasti doesn’t really take any damage. I don’t think he has ever protected it and it was grown from seed I believe. These pictures are from a few weeks ago after our coldest winter in years...