Hardy Tropicals UK

As this is one of the most common questions due DIY Sheds selling them, and sometimes labelled as 'Hardy', I have put this information in a dedicated topic. The info below has been written in reply to previous topics but is not easy to find.

Obviously each person's experience will be different, but at the time of writing in early 2009, the consensus of experienced palms growers was that the figures were about right. Also this was written before the run of harsh winters started, and where as some of us had Washingtonia growing unprotected, in recent winters some form of protection IS required to get even mature palms through. There are exceptions ie Southsea on Portsea Island, but but these are rare, and we have to regards Washingtonia robusta as Half Hardy. Washingtonia filifera, on paper, can take colder conditions than robusta, but it requires a dry climate, which we find difficult to provide.

Washingtonia robusta hardiness rating in UK - Spring 2009
Exotic gardening for many plants is still in it's infancy, so what we all did 10 years ago is probably different to what we would do now. It is amazing how new information can totally supercede what we were doing before. The basjoo protection in that page I learned from Angus White of Architectural Plants back in the early 1990s and was based around the -19C temps they got at the Nuthurst Nursery in Feb 1991.

I have edited my webpages a couple of times in the 5 years since the information was written, as it does change. You look at a page for the first time in a couple of years, and think OMG did I write that followed by a hasty rewrite

Ok I've been growing Washingtonia from seed since the late 1970s, and lost my first batch of 5/6 year old palms, that were planted out, in the winter of 1984, so since then have grown them as a pot/tub plants until they got too big to house. Only then did I try them outside again.

My experience is noted as a 'plant label tags' is below. This is my attempt to show that hardiness improves with trunk size, and will hopefully deter people planting out seedlings that stand no chance of withstanding even a mild UK winter. There are numerous variables that can affect hardiness, the biggest being the duration of the cold. I do not expect even mature trunk size Washies to survive more than 2 or 3 days of freeze. Palm health will also play a big part. Damaged or unhealthy palms are less likely to take cold. Some may dispute the small seedling leaf hardiness figures and indeed the leaves can be tough, but even if they do not show frost damage they are not much good if the palm has been killed

I expect some debate over these figures, they are just my interpretation of Washingtonia robusta hardiness.

mature trunk diameter greater than 25cm
Leaves above -3C
Leaves -3C to-5C
Leaves below -5C
Palm above -5C
Palm -5C to -8C
Palm below -8C

Juvenile trunk diameter 15 - 25cm
Leaves above -3C
Leaves -3C to-5C
Leaves below -5C
Palm above -3C
Palm -3C to -6C
Palm below -6C

Large seedling - trunk diameter 10 -15cm
Leaves above -2C
Leaves -2C to-4C
Leaves below -4C
Palm above -2C
Palm -2C to -5C
Palm below -5C

Seedling - trunk diameter 5 - 10cm
Leaves above -0C
Leaves -0C to -3C
Leaves below -3C
Palm above -0C
Palm -0C to -3C
Palm below -3C

Small Seedling - trunk diameter Under 5cm
Leaves above +2C
Leaves +2C to -1C
Leaves below -1C
Palm above +2C
Palm +2C to -1C
Palm below -1C

All trunk sizes
Winter Dry
Winter Wet
Shelter
Exposed
Good air flow
Wapped

As said in the forewood, in recent winters have been more harsh, so for most of us som form of protection will be required. For me in winter 20010/11 (December) I had -10C and with 33cm of snow. The protection I gave was a plastic covered parasol to keep snow and radiation frost out of the crown, together with 200w of rope lights when temps dipped below freezing.

PLEASE NOTE this is a mature trunk palm and seedling/juvenile would need substantially more protection, but they hate being wrapped as this allows fungal infection and rot

Please only reply to this on the hardiness discussion, and start other topics on protection and general discussion

No one could or should argue with you Washy success Dave-super nice.

I do wonder if it is a pure Robusta though-my guess would be it(at the very least)
has some Filifera running through it's plant "veins."

Hello Dave Brown, I'm from Poland, Can I use your pictures of Washingtonia in our Polish forum ?? Please

I think that the amazing success that you have had with Washingtonia, should make us think again about how durable these palms can potentially be given a bit of support.

Dave Brown wrote:As this is one of the most common questions due DIY Sheds selling them, and sometimes labelled as 'Hardy', I have put this information in a dedicated topic. The info below has been written in reply to previous topics but is not easy to find.

Obviously each person's experience will be different, but at the time of writing in early 2009, the consensus of experienced palms growers was that the figures were about right. Also this was written before the run of harsh winters started, and where as some of us had Washingtonia growing unprotected, in recent winters some form of protection IS required to get even mature palms through. There are exceptions ie Southsea on Portsea Island, but but these are rare, and we have to regards Washingtonia robusta as Half Hardy. Washingtonia filifera, on paper, can take colder conditions than robusta, but it requires a dry climate, which we find difficult to provide.

Washingtonia robusta hardiness rating in UK - Spring 2009
Exotic gardening for many plants is still in it's infancy, so what we all did 10 years ago is probably different to what we would do now. It is amazing how new information can totally supercede what we were doing before. The basjoo protection in that page I learned from Angus White of Architectural Plants back in the early 1990s and was based around the -19C temps they got at the Nuthurst Nursery in Feb 1991.

I have edited my webpages a couple of times in the 5 years since the information was written, as it does change. You look at a page for the first time in a couple of years, and think OMG did I write that followed by a hasty rewrite

Ok I've been growing Washingtonia from seed since the late 1970s, and lost my first batch of 5/6 year old palms, that were planted out, in the winter of 1984, so since then have grown them as a pot/tub plants until they got too big to house. Only then did I try them outside again.

My experience is noted as a 'plant label tags' is below. This is my attempt to show that hardiness improves with trunk size, and will hopefully deter people planting out seedlings that stand no chance of withstanding even a mild UK winter. There are numerous variables that can affect hardiness, the biggest being the duration of the cold. I do not expect even mature trunk size Washies to survive more than 2 or 3 days of freeze. Palm health will also play a big part. Damaged or unhealthy palms are less likely to take cold. Some may dispute the small seedling leaf hardiness figures and indeed the leaves can be tough, but even if they do not show frost damage they are not much good if the palm has been killed

I expect some debate over these figures, they are just my interpretation of Washingtonia robusta hardiness.

mature trunk diameter greater than 25cm
Leaves above -3C
Leaves -3C to-5C
Leaves below -5C
Palm above -5C
Palm -5C to -8C
Palm below -8C

Juvenile trunk diameter 15 - 25cm
Leaves above -3C
Leaves -3C to-5C
Leaves below -5C
Palm above -3C
Palm -3C to -6C
Palm below -6C

Large seedling - trunk diameter 10 -15cm
Leaves above -2C
Leaves -2C to-4C
Leaves below -4C
Palm above -2C
Palm -2C to -5C
Palm below -5C

Seedling - trunk diameter 5 - 10cm
Leaves above -0C
Leaves -0C to -3C
Leaves below -3C
Palm above -0C
Palm -0C to -3C
Palm below -3C

Small Seedling - trunk diameter Under 5cm
Leaves above +2C
Leaves +2C to -1C
Leaves below -1C
Palm above +2C
Palm +2C to -1C
Palm below -1C

All trunk sizes
Winter Dry
Winter Wet
Shelter
Exposed
Good air flow
Wapped

As said in the forewood, in recent winters have been more harsh, so for most of us som form of protection will be required. For me in winter 20010/11 (December) I had -10C and with 33cm of snow. The protection I gave was a plastic covered parasol to keep snow and radiation frost out of the crown, together with 200w of rope lights when temps dipped below freezing.

PLEASE NOTE this is a mature trunk palm and seedling/juvenile would need supstantially more protection, but they hate being wrapped as this allows fungal infection and rot

Please only reply to this on the hardiness discussion, and start other topics on protection

Dave, your W, Robusta has got style.

Just like to add that Washies do not like to be watered winter.
If it rains that's OK but I lost my first good size outdoor Washy by a winter water.
Cheers: Ian Mc

Ian Mc1 wrote:Just like to add that Washies do not like to be watered winter.
If it rains that's OK but I lost my first good size outdoor Washy by a winter water.
Cheers: Ian Mc

I have to agree with Ian, I keep mine as dry as possible with shelters during winters.

I am really starting to like this palm but I don't think it would do very well here at all without protection. I know Jimhardy has a nice one in a zone 5B with a fare bit or protection so I might try it with minimal protection next year. I just don't think it would stand a chance here with nothing at all. the last 5 years the lowest I have seen was -9C but that would burn the leaves and most likly kill the trunk as well

miketropic wrote:I just don't think it would stand a chance here with nothing at all. the last 5 years the lowest I have seen was -9C but that would burn the leaves and most likly kill the trunk as well

I had -10C with a parasol over it Mike

I have most pics on facebook the link to the album is HERE

G day Dave

Great pictures on the timeline of your Washingtonia robusta the parasol must do a good job to stay on in strong winds .

Anyway my cousin and his wife have a Washingtonia robusta in their garden that i gave them back in 1995 for a wedding present !!! They live in an inland valley that is extremely frosty for around 5 months of the year .
The palm is about 5m tall i guess and is planted out in an open area . Every few yrs the palm sees winter-lows of around
- 7 C and - 9 C on one occasion . The washy was defoliated at both these temperatures and looked like a blow torch had taken to it after the - 9 C incident . The palm has always grown back a full set of leaves after every hard freeze event . No snowfall or wet soggy conditions must help it along . Also the temperature always gets to at least 7c on the coldest winter days .

I will take a picture of it next time i visit .

Cheers Troy

well you give me hope Dave it seems yours puts on nice growth spurts in the summer as well. I think I will get one this spring and give it a go. suppose to be around -7c the next couple nights so I am really interested to find our winter low and see what a washy can handle.

miketropic wrote:well you give me hope Dave it seems yours puts on nice growth spurts in the summer as well.

You forget, we don't get a summer as you know it. We get a very long spring, then Autumn

miketropic wrote:I think I will get one this spring and give it a go. suppose to be around -7c the next couple nights so I am really interested to find our winter low and see what a washy can handle.

They are ok in frosty nights down to -5C, get defoliation without protection below that, but hate freezes where temps stay below, during the day.

most of the time we will creep above freezeing..today was a high of 4 C and a nightime low of -7 so it will get above freezeing for a bit every day

My recently purchased Washy seems to be doing ok, apart from browning of the leaf tips and a few of the leaves appearing to fold (concertina). I was wondering whether it was needing a drink so gave it half a watering can full yesterday. The palm is in a 10litre pot and is approx 4 foot tall. Will be going in the ground when we move house in a couple of weeks. Can anybody suggest a cause/solution? Forgot to say that it has been in an unheated garage for the past few weeks.

Phatplants a picture would help with the diagnosis otherwise it is really hard to tell if it is healthy or it is on the brink of death, need more information and a picture is the best and easiest method.