19 hours ago, MJSanDiego said:

@sonoranfans according to @Merlyn his big mature Foxtails all died at 28 and frost. @Merlyndid we both remove Queens today? 🤣

length of cold can be more important than 1-2 degrees as there will be thermal equilibrium between air and plant in a longer cold  event.  In shorter cold snaps -like out west- thermal equilibruim is often not reached.  I saw a royal that survived 18F at treeland nursery in chandler arizona completely exposed no building nearby.  But that was a real short cold snap where it was 55F at 1PM that day.  Big overnight temp differences is common with low humidity places.  My own (former) place in arizona my (3) bismarckia were defoliated save the spear and the queens were badly burned.  18F in florida will undoubtedly kill all those species of palms because our climate warms more slowly after a low.  My area in florida has a coastal influence so we dont get as cold or stay cold as long as Merlyns area.  My neighborhood has surviving foxtails all over, none died in that 2010 cold event 28x2.  We know on palmtalk that zone ratings dont mean that much because length of cold event or cool season are not considered as survival criteria.  One of the great things about palmtalk is that you can have a single species grown in the desert, mediterranean climate, and humid subtropical coastal and inland climates and see there are substantial differences in cold tolerance.  I would think that in san diego  you will have short cold events so the high 20's shouldnt be a problem. 

1 hour ago, sonoranfans said:

length of cold can be more important than 1-2 degrees as there l be thermal equilibrium between air and plant 

Yep, many variables, humidity, frost or not, timeframes, etc. I have never seen temps below 36 here and it was like two nights. But I still won't plant a zone 11 palm (40+), I just don't think it's ideal, and one day will cause unnecessary stress and weakening to the palm,  plus unsightly for a spell. I use the zone info to determine which palms will have no cold damage for life. Just my humble opinion, great topic thanks

@Xenon there's a cluster of Royals at an RV dealership at I-4 and the Lake Monroe bridge, they have been there for at least 11 years and possibly a couple more.  The dealership popped up with them sometime between 2011 and 2013 on Google streetview.  There is one more Royal in a public road planting, and two in a backyard in Lake Mary.  They aren't popular around here, probably because of the giant KABOOM the falling fronds make.   

Two doors down from the pair of Royals is a planting of 6 big, mature trunk foxtails.  They were planted about the same time in ~May 2021.  In the January 2022 freeze (24.6F in my backyard) they were all 100% defoliated.  By April both Royals looked like nothing had happened.  One Foxtail died, two others struggled to put out one frond by ~June but survived, the other three regrew and looked pretty normal by ~June.  The closest "official" Sanford weather history had a low of only 31F on 1/30/22, but I recorded 27.5F in the front yard and 24.4-25.5F in the backyard, 2 sensors in logging in each spot.  So it's hard to judge what the actual temp was at the Royals and Foxtails.  Just based on the limited samples around here, I'd guess Royals are a wee bit tougher.

5 hours ago, Merlyn said:

Two doors down from the pair of Royals is a planting of 6 big, mature trunk foxtails.  They were planted about the same time in ~May 2021. 

I was thinking the age of the palm in conjunction with when it was planted could potentially make a difference too. If the Foxtails were planted many years ago as babies in 5 gallon pots, and grew to the same size by 2021 as those big ones planted in 2021, they might be more cold hardy during that 2024 freeze due to acclimating over the years with more established roots. Just another possible variation. Great discussion 

Dateline Tampa: Photo of a dead Sylvester, 20yo-ish (likely fusarium?) that just grew very fast, adjacent to Washingtonian planted as a juvenile (I carried it in a small pot to the designated spot) at the same time ie 15 years ago, and then the Queen - 57 yrs old! (I’ve been here along time!) (Sylvester coming out ASAP, but it’s big and in a tight spot… also hardly ever ‘groom’ my palms anymore… they live longer but the neighbors don’t like me as much) Cheers

That Queen palm is positively a dwarf at 57 years old! I’ve got 20 year olds that are triple that size or even taller. So sorry for that Sylvester.