Washingtonia robusta

Discussion in 'Outdoor Tropicals' started by LPN, Sep 16, 2006.

  1. LPN

    LPN Well-Known Member 10 Years

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    A palm not for the faint of heart here in the PNW. Almost certain to die unless a rain canopy is errected during the winter. Deep drainage is essential for survival. More people have killed this palm than any other in these parts. Many fall victim when people mistake them for Windmill palms and seem to be readily available. I sure some people unknowingly still think they've killed a Windmill without being able to see the difference.

    Cheers, LPN.
     

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  2. Ron B

    Ron B Paragon of Plants 10 Years

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    As with many other tender plants, it's not the rain. It's the temperature falling below their minimum requirement. Planted where frost is kept off, as is a Washingtonia at a hospital near me, they can live. This specimen is open to the rain but protected from frost by a physical plant outlet that blows a plume of warm air probably about 30m high. Other examples planted in ordinary conditions here have lived through years of rain, only to die when it finally got to cold for them.
     
  3. LPN

    LPN Well-Known Member 10 Years

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    I've seen that Washingtonia robusta in Edmonds (on the hospital grounds) if I'm not mistaken, planted near an exhaust vent.
    You're right about lower than tolerable temps for these palms. Some folks have built temporary enclosures and a portable heat source for such times.

    Cheers, LPN.
     
  4. Ron B

    Ron B Paragon of Plants 10 Years

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    Up the street they had washingtonias and windmills for some years, the washingtonias eventually died and left behind the windmills, which continued on until being removed themselves (change in ownership?) leaving the small open front yard even less well-planted than before. As was said earlier, both are easily found at outlets here but only the windmills persist for the long term on most sites.
     
  5. LPN

    LPN Well-Known Member 10 Years

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    Speaking of persistance, I drove past a lone Trachycarpus fortunei planted in a farm/pasture field while out driving today. It certainly looked out of place but had endured the last 10 years or so and stood 8' - 10 feet. Evidence of a hay bailer passing by, but close enough not to damage the trunk.
    I've also seen a large cluster of Musa basjoo in a farm field, seemigly placed there by accident for compost or by a banana pixie. Seemed odd, a field of potatoes and a grove of bananas.

    Cheers, LPN.
     
  6. Ron B

    Ron B Paragon of Plants 10 Years

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    I've never been able to get the Japanese banana to take. A conspicuous clump in front of a house north of UBC was said by the man answering the door to have been already present when he came to work there in the 1950s.
     
  7. Ian

    Ian Active Member

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    A mature Washingtonia robusta grows in downtown Truth or Consequences, New Mexico, where temperatures fall into the teens every winter, sometimes lower. A completely different climate of course, but to blame the failure of this species in our climate on just one variable is oversimplifying things a bit.
     
  8. LPN

    LPN Well-Known Member 10 Years

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    Ian ... I have some of the T or C seed from you. All doing very well and into a second years growth with no ill effects. I have given some of them away to fellow gardeners to see how they perform in their gardens.

    Cheers, LPN (Barrie)
     
  9. Ron B

    Ron B Paragon of Plants 10 Years

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    Actually the common oversimplification is to say palms etc. will be hardy here because they sometimes experience similar low temperatures elsewhere. All plants do have a minimum temperature below which they fail. Here in the North the ground freezes up during cold periods, a few nights in the teens in California does not have this effect.

    Washingtonia living on various sites up here until the temperature falls too low for them quite definitely points to cold being the critical factor. If impeded drainage, calcium levels whatever were lethal here they would not grow until a cold winter came and then die.
     
  10. Ian

    Ian Active Member

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    Barrie, those are W. filifera seeds I sent you. The W. robusta is an isolated tree that does not set seed.

    Ron you're right about that misconception, but it's still remarkable how much more cold these palms can handle in a climate with very dry winters and hot summers. For example, the one in Truth or Consequences (the northernmost large, long-established one I know of in NM) has to have lived through temperatures below 10F a number of times, and some ground freezing, though I'm sure ground freezing is not as destructive when it is bone dry. On the other hand, in our climate, it always dies below 15F, sometimes higher.
     
  11. Daniel Mosquin

    Daniel Mosquin Paragon of Plants UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    Had I but known about that T or C palm, I would have visited it this past spring. Ah well, another time - I'm planning a trip back to the area.
     
  12. Ron B

    Ron B Paragon of Plants 10 Years

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    Prolonged cold freezing the ground ~deeply presents different problems than short periods of cold followed by return to warming, as often happens in warm southern climates. Up here when it's 15F it's during an Arctic front that may last 2 or 3 weeks. In addition to lack of significant, lingering frost penetration plant in places like the desert Southwest also receive the benefit of long, blazing summers maturing their growth and making them fully hardy well before any frigid weather that may occur. Even some plants grown in the humid East are not as cold tolerant here as back there, because of the lack of summer heat maturing their growth and enabling them to achieve their full hardiness before frost.
     
  13. LPN

    LPN Well-Known Member 10 Years

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    Ron B
    "Up here when it's 15F it's during an Arctic front that may last 2 or 3 weeks." Interesting ... I may be getting old but, when was it that cold for that long?

    Ian ... I wondered about wether or not it was W. filifera or W. robusta. Early indications are that they are robusta (much reddish coloring in the leaf bases). I thought that perhaps even if you collected from a filifera, it may have been crossed with a robusta (filabusta). Any thoughts as to what we / I have here?

    Cheers, LPN (Barrie)
     
  14. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    Agree with Ron.

    At my latitude (55°N), a night when it falls to -10°C, the following day the sun only gets 13° above the horizon and the temperature won't rise above about -5°C, unless there's a change in the wind direction bringing in warm air off the sea.

    But a night in NM or AZ at -10°C, the daytime sun gets 35° above the horizon and the temperature will easily shoot up to +5°C or more with solar radiation alone.
     
  15. Ian

    Ian Active Member

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    Barrie... for sure it is pure filifera. The one lone robusta nearby that I referred to earlier does not flower because it is not irrigated. Other than that there are no other mature Washingtonias within at least a mile of these palms.... down the road apace in Elephant Butte there may be a few but mostly younger plants.

    Last time we had a 3 week long Arctic blast in the Seattle area was January 1950 (arguably January 1969 but with no really extreme temps until the end of the event). We have had a number of events that could marginally qualify as 2 weeks long in the 80s, especially Nov-Dec 85, or things like the Dec 1990 freeze when it got cold, then warmed up, then really cold again over a period of 11-12 days.

    Speaking specifically of air temperatures... prolonged freezing events in New Mexico are less common but they do occur. Looking at climate data for Truth or Consequences I see that in December 1987 a freeze occured with several consecutive days of lows in the single digits F or worse (lowest -5F) and highs in the low 20s - low 30s just the way it happens here. If the palms lived through that once they could do it again. I agree though that even with highs in the 20s the increased amount of solar radiation throughout the winter in general would probably keep the soil from freezing very deeply. Also agree as far as the summer heat goes... it is another factor in the mix of plant hardiness in their climate vs. ours.
     
  16. LPN

    LPN Well-Known Member 10 Years

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    Ian ... that's good to know that they are pure filifera. The leaf color is quite a bit grayer than robusta. I think I'll plant a few out this year and give 'em temporary protection when it's called for.

    Cheers, Barrie.
     
  17. flipper83

    flipper83 Member

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    I've got a mixture of filifera's and robusta's in seedlings right now. A friend of mine took a few filiferas over to Pender Island last winter, and they performed really well.
    I'm going to also try to keep a close eye on the ones I have and see if they can possibly winter. Maybe a little getting used to slightly cooler temperatures will allow them to grow to decent size. Then again, this could be wishful thinking.
    As a side, Costco here on the lower Island was selling decent sized robusta's for two years consecutive now. You would think that if they didn't grow that the returns would have told them not to order them again.

    Ken
     
  18. LPN

    LPN Well-Known Member 10 Years

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    Ken,
    The Washingtonia robusta at the top of this thread is one of those Costco, 15 gallon palms. I think if they sell them as "not winter hardy", you're on your own.

    Cheers, LPN.
     
  19. Ron B

    Ron B Paragon of Plants 10 Years

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    If you want them to last you have to provide some kind of protection at some point.

    "W. filifera...Hardy to 18F/-8C"

    "W. robusta...Hardy to 20F/-7C"

    -- Sunset WESTERN GARDEN BOOK
     
  20. LPN

    LPN Well-Known Member 10 Years

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    Driving around I have noticed a few W. robusta planted in local gardens. I'm quite certain the owners don't know the difference between Washingtonia and Trachycarpus, fed up, will yank them out, never to plant a palm again.

    Cheers, LPN.
     

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