A customer came into the nursery recently saying, "So few people know that Roystonea borinquena is more cold hardy than regia".  He explained that in his garden (Encinitas area) the R. borinquena did much better with the cold and had hardly any cold burn.  His R. regia showed a lot of damage.  His garden is a few miles from us, and we experienced 25 degrees last winter.  So, although I didn't ask his low, I assume that it was similar.   After my discussion with him, I asked a few other customers about it and heard that the borinquena show less frizzle tip from cold along the Coast than the regia.  Perhaps everyone's scenario will be different, but I've always felt that regia was the best for cold.  Now, I am not so sure.  We had a lot of regias outdoors that saw 25 degrees and most suffered some damage.  Now, eleven months later, all have recovered and I know of none that actually died.  Most were either 15g, 25g or box sized and had been outdoors for at least one year.  None were protected.  What's your experience so far?

Phil

Hi, Phil:

For what little it may be worth, I have heard over quite a few years that R. borinquena is the coldhardiest of the genus.  OTOH, borinquena, at least in habitat, has been the least attractive because the trunk is less symmetrical and thinner than others I see.  My impression is that R. oleracea is the most attractive, and less coldhardy than the Florida spp.  

Best Wishes,

merrill

(Phil @ Dec. 03 2007,08:33)

QUOTE

A customer came into the nursery recently saying, "So few people know that Roystonea borinquena is more cold hardy than regia".  He explained that in his garden (Encinitas area) the R. borinquena did much better with the cold and had hardly any cold burn.  His R. regia showed a lot of damage.  His garden is a few miles from us, and we experienced 25 degrees last winter.  So, although I didn't ask his low, I assume that it was similar.   After my discussion with him, I asked a few other customers about it and heard that the borinquena show less frizzle tip from cold along the Coast than the regia.  Perhaps everyone's scenario will be different, but I've always felt that regia was the best for cold.  Now, I am not so sure.  We had a lot of regias outdoors that saw 25 degrees and most suffered some damage.  Now, eleven months later, all have recovered and I know of none that actually died.  Most were either 15g, 25g or box sized and had been outdoors for at least one year.  None were protected.  What's your experience so far?

Phil

the ambient temp is actually kind of an incomplete stat, I suspect it would be the temp of the bud that would matter.  The nursery I favor(treeland) in chandler arizona has a regia(12+ footer) that was defoliated last winter at a measured 20 degrees F, no over head canopy.  It is back, with 4 new spears and looks pretty good.  The thing is, wind was zero(no wind chill) according to weather underground station at that site, and it warmed up by +10 degrees 4 hours after the low.  I had read that florida adapted regia were the most coldhardy, but even data from florida can be conflicting, cold hardier species have been reported to die when the "less cold hardy" survive nearby in the same yard.  In a few years I will know how the borinquena are, perhaps, as I have 3 that are just evolving their first pinnate fronds(inside my shadehouse).  

A geographical inspection of the two countries reveals that cuba has a much greater percentage of lowlands, puerto rico has quite alot of 2000+ elevation forrest land.  the whole center of the island appears to be 1500-3500 ft in elevation.  Perhaps the royals in the uplands of puerto rico see more cold due to the elevation.

My regia was 100% brown the first day of the freeze last January. It saw 26F - maybe 25F. The second photo is from September. It now has another long spear about to open.

I have to give R. borinquena a try if it's even a tie with the Cuban Royal.

Here's what I experienced:

All of my 10 borinquenas in 5g, located at the highest elevation on the property, croaked. These were protected from wind and had partial canopy from eucalyptus trees.

Of 30 regias in 5g, located at the lowest elevation, I lost about 50%. These were on the windward side of property and had no canopy at all. The survivors have come back strong.

Both sets of these plants left the greenhouse, and were shifted up w/ the same soil, at the same time. They had not been established long in these containers.

Both 25g regias, finally planted last summer, have survived, although growth this summer was slower than normal. One of these looks like it might be on its way out though. Spears have been marked to confirm growth or not. These were also at my lowest elevation and in the complete open. I have my fingers crossed!

Having grown up in South Florida, the royal is one of my favorites! Even though they may not grow great out here.

Only had one outdoor temp gauge, on the east side of prop and under a patio cover (wind and frost protected) read 32F for the lowest temp. I did get frost at least one night.

My Regias did not skip a beat over the 2007 freeze.  Both did not suffer any frond damage.  I am surprised to see Terry's was badly damage in Oceanside.

My regia saw 20d. with no canopy and had absolutely no damage.  I couldn't believe it.  Nearby Arch.  tuckerii's got fried and barely survived,  but the regia didn't even brown spot.  I keep having to say this, but I am on a steep hill with excellent water and air drainage and my results are probably not typical.  I don't have a borinquena to compare however.

I was thinking about measuring temperatures and it occurred to me that measuring the air temp may not tell the whole story as the palm bud temp is really most important(according to what I've read).  Air temps fluctuate alot due to natural convection, but ground temps do not and may be more indicative of the heat available from a certain location.  Perhaps the ground temps differ alot, and heat rising from the ground can blunt the overnight low temp of the PALM in dry areas where temps fluctuate alot.  Just before the freeze of '07, I watered the dry ground deeply with drip irrigation from 5:30PM until midnight and my bismarckia survived 10 hours below 26F(air temps hit 20.3 degrees), which is typically considered not survivable for bismarckia.  All fronds were burned, but they grew 7-9 new ones this year, coming back strong.  But I am willing to bet the ground temps never approached 25F as ice was not obvious in the dirt(not crunchy) around my palms next morning.  I had read on the internet that watering just before a freeze was a good idea as long as it was a short term freeze.  I had also read that the lower the bud, the colder it would be, next to the ground as heat rises from the ground, warms the air leaving the ground cold.  If the water did what I think it did, kept the palm warm by keeping the ground warm, its a further argument for developing good drainage in dry climates where the lows tend to be temporary.  Water than runs off cannot keep the local ground warm.

By the way, the local nursery men here all say that palms in pots are much more susceptible to a killing freeze.

You can't directly compare potted plants to those in ground. I expect potted stock to lose about 10Fº of cold hardiness. Nurseries generally cover their potted material with a tarp on cold nights to trap some ground heat.

I have 3 regias. 2 suffered no damage whatsoever. The third had extensive damage to 2 fronds and were cut off this summer. If I recall correctly, I was at 29F low for 2 nights.

(Peter @ Dec. 03 2007,11:56)

QUOTE

My regia saw 20d. with no canopy and had absolutely no damage.  I couldn't believe it.  Nearby Arch.  tuckerii's got fried and barely survived,  but the regia didn't even brown spot.  I keep having to say this, but I am on a steep hill with excellent water and air drainage and my results are probably not typical.  I don't have a borinquena to compare however.

That's amazing Peter.  These must be overhead, no?  I can't imagine 20F not killing it outright. No damage?  That's wierd.

I bought what was labeled a R. Regia as a fifteen gallon back in 2001, but most people say it looks more like a R. Oleracea.  It saw 24 degrees during the freeze event here in Mission Viejo and was slightly burnt and frizzled but bounced back nicely in the spring.  Every winter the older fronds get somewhat dried and frizzled by the Santa Anas but looks great by the end of summer. BTW, it also is my fastest palm at putting on height, just ahead of my Caryota Urens as you can see from the below before (May 2002) and after (May 2007) pics:

Brett - Looks like a regia to me. Leaves are as plumose as mine. NICE regia though!

My R. borenquenea suffered no damage at all with 26F low. Nearby Archontophoenix alexandrae was defoliated but recovered and several tall A. Illawaras nearby were also burned badly.  My little borenquenea, 14" tall at the time, had no overhead protection and had been in the ground for two winters from a two leaf seedling. This summer it zoomed up to 30" tall and its trunk base is fattening up nicely. The other thing to note is that R. borenquenea seems to hold its deep green color better than R. regia during long periods of cool weather which seems to yellow out in my experience.

I had 2 Roystonea Regia and 1 Borenquena and all died at 23F. What would one expect. However one of the Regia standing at 6 feet survived for quite a while, but then died this summer. I think I put some covers over them, but nothing serious.