Lessons from the cold - post yours

[L.A.M.]

1. Don't plant marginal plants in full sun in a wind-sheltered location. To plant them in such locations is advice I've heard before but terrible from my experience. My personal weather station regularly records lower temperatures on winter nights and higher temperatures during the day (especially in summer) than the general area, which has fried our dwarf Alberta spruces and killed my Birmingham palmettos and one of my needle palms. Wind and/or shade will actually prevent the ground from heating up or cooling off too much due to uncontrolled radiation; furthermore, shade can limit frost accumulation from the sky.
2. Don't let your guard down. This applies to both before and after the cold wave. From my experience, temperature extremes, both cold and hot, are underestimated early in the forecast and updated to be more accurate closer to time. After the cold wave, don't assume you're out of the woods too soon; it takes weeks if not months for palms to show signs of damage in most cases. Don't prune the dead growth; that could actually protect it from a second winter/spring cold event. Have copper-based fungicide ready (copper works on bacteria, too) at all times just in case you end up needing it. If the spear pulls but there isn't yet an odor of rot from the maristem, or the base of the older fronds are showing damage, pour copper fungicide in the bud as a last-ditch effort to save it or just to be on the safe side in case the newer fronds (possibly even newest) are damaged too.
3. Be prepared for a multi-decade cold event. In December 2022, we had our worst cold wave since February 1996. My dwarf palmetto and remaining needle palm seem to be fine for now, but only the needle palm was unscathed. (I still can't completely rule out the possibility of worse, though; see above.) To add to that, Cookeville isn't as warm on average as even some parts of Virginia, Kentucky, Missouri and Illinois, let alone most of Tennessee. If you live in the Upland South like me, it's best to stick with needle palms and dwarf palmettos, MAYBE Birmingham, Brazoria and Louisiana palmettos. Even then, I repeat, do not let the extra summer heat and sunshine fool you into thinking a wind-sheltered and sky-exposed location is better; I've noticed the opposite.
4. Don't believe myths. That Chinese windmill palms are able to regularly deal with temperatures below -14 degrees Celsius (10 degrees Fahrenheit) and are the most cold-hardy palm in the world are terrible misconceptions. It's even given palms in general a bad rap in Memphis due to totalitarian local ordinances and the widespread misconceptions, even with historical evidence to the contrary in Knoxville. (Some of these old Knoxville palms even miraculously later survived the -31 degree C/-24 degree F horror in January 1985.) Generally, native palms are more reliable than non-native ones, especially in marginal areas. https://dailymemphian.com/article/393/Memphis-BBQ-chain-Tops-to-yank-out-dead-palm-trees https://palms.org/wp-content/uploads/2016/05/v18n1p25-30.pdf
5. Keep some in pots. It may be less expensive to grow many palms from seed than purchase a few pre-grown, even though they'll take longer to mature. Plus, they'll be raised in your climate. However, keep in mind that pots get colder than the earth itself does; you'll need to bury your pots for the winter, insulate them or bring them indoors if it gets below about -5 degrees Celsius (23 degrees Fahrenheit). This isn't unique to palms, either; even white spruce roots can be badly damaged by colder soil temperatures. This also means that if a bad cold event is coming, you could leave some out to weather it in the hopes of acclimation while still moving others indoors to be on the safe side. Last but not least, it's probably not as difficult to divide clustering palms like needle palms and European fan palms if they're in pots as it would be if you've transplanted them, allowing you to move the clones into their own pots to become separate plants without damaging the parent; this applies for some yuccas too.
6. Watch out for temperature inversions. Valleys and basins are often prone to temperature inversions that can make it a few degrees colder than surrounding areas. This tends to be worse at night, in winter/spring, in the actual floodplain, in smaller valleys and in north-south valleys than during the day, in summer/autumn, on the hillsides (even a few feet above the floodplain), in bigger valleys and in east-west valleys. Be especially careful if the floodplain is open to the sky, and the creek is dry; the ground will cool off more rapidly if there's no shade (nor wind) to block thermal radiation and little soil moisture to resist temperature changes.
7. Be careful when you transplant. Palms can take an entire growing season to establish healthy roots, even with supplemental water. Until then, they'll be more vulnerable to freezing. It's probably best to plant in April in USDA Zone 6b to 7b, March to May in 8a to 9a and February to June in 9b. (It won't matter much in Zone 10a or higher, and palms can't thrive in Zone 6a or lower.) I planted my Birmingham palmettos in May 2021 (in Zone 7a) instead of April because we waited for our vaccinations to take effect before going to New Bern to get them; ultimately, they succumbed to the January 2022 cold wave, one of the three even taking until autumn to completely die, because they didn't have a full growing season to prepare. (My yard's bad microclimate didn't help, but the point still stands; my needle palm planted in April 2019 turned out OK, after all.)
8. Don't be shy about clay, shade, snow or wetlands. Most of the subtropical palms native to southeastern and south-central North America, excluding saw palmettos, thrive in wet soil. Even if they can tolerate dry soil, it can be helpful to plant them in wet soil; they won't need as much supplemental water to establish in a shady clay valley as they will on a sunny sandy hilltop. Furthermore, cabbage and Birmingham palmettos can still thrive in partial shade and needle palms and dwarf palmettos even in full shade, and it can both catch frost accumulation and prevent local temperature extremes. (I'm still not sure whether Louisiana and Brazoria palmettos can tolerate full shade or just partial.) Dwarf palmettos can even tolerate growing under walnut and hickory trees, which infamously poison the soil too much for even many other native plants to thrive.
9. If you fertilize, consider doing it year-round. Thankfully, some parts of Tennessee like the Outer Nashville Basin and Great Appalachian Valley have naturally fertile soil. This probably applies to floodplains anywhere, but I mean outside of the floodplain. However, if you choose to fertilize anyways or don't have naturally fertile soil, it could be worth doing it during winter too. Even a recovering but still-alive palm could use winter fertilization. Palms are monocotyledonous, not dicotyledonous, trees/shrubs, so they still grow in cold weather as long as they're alive; it just slows to a much less noticeable pace. Fertilizing palms, yuccas, bamboo or aloes isn't as effective for their overall growth during winter, but it won't backfire like it will for dicot trees/shrubs, and it can even save a palm that has lost its spear but still not succumbed to a maristem infection. http://extension.msstate.edu/publications/publications/cold-injury-palms

Edited February 6, 2023 by L.A.M.

[Swolte]

Ugh, just learned a very hard lesson. 

Don't leave protections on for too long, especially after big rains. I am seeing 50% spear pull on many of my valuable palms (a percentage of that may be fatal) so this winter was officially worse than the '21 one for me. I think the damage was mostly due to the protections being on for too long after rains. The ground became saturated and, with Texas temperature swings, it quickly started brewing under those frost blankets. 

Oh man, I have left protections on for 8+ weeks before, however, I didn't get a foot of water poured down from the heavens in such a relatively short time. Dealing with intense periods at work and a newborn weren't conducive to me checking in on palms either as I definitely knew better! Just pulled a spear on a 'well protected' JxS so really quite bummed about it all. I am thinking most palms may pull through but its a serious setback for what I was hoping would be a good growing year (last year was not at all). On a positive note, I am glad I bought the copper fungicide concentrate so I will have enough to last me a year of spraying, hah!

I'll spare you the painful pics... 

[ryjohn]

I see the value of the recommendations for siting palms under overhead protection, out of full winter sun, and not removing canopy trees.  But I also will point out that a palm sited in full sun with no root competition from shade trees, grass, or weeds will grow at least five times faster than one that lacks those two conditions.  So you likely will grow a more impressive palm in 5 years of “optimal growth siting” than you could in 25 years of “optimal cold protection” siting.  Your level of risk tolerance and the standard deviation of winter lows in your area will affect this decision, but in my opinion for sure all the less expensive sabals and Washingtonias belong out in full sun with no root competition from canopy trees as they are easy and cheap to start over with.

Edited February 7, 2023 by ryjohn

[MarcusH]

I'm a zone pusher myself.  I've planted a Queen in zone 8b.  My young palm lost all its fronds in December 2022 but surivived night/morning temperatures of 16,21,24,28F with little protection only.  Not going to brag about it but it went through this cold winter better than I thought which encouraged me to plant a second Queen . They're cheap and fast growing in our area so in case there's going to be another February 2021 winter I'll just chop it down and replant another one until then I'll enjoy the looks of it. No lesson learned . 

[Harry’s Palms]

I have learned that the effect of a cold snap on palms is quite selective. In my yard there are palms that should have not survived the twenty years that they have been in the ground and others that just give up and die that are supposed to be more hardy. I have lost 3 Woodyetia's but have a Venezuelan Royal that just keeps on going. Two blocks away , my palm friend has a beautiful Woodyetia but can't grow a Royal. I have a Pritchardia that is doing well but he has lost very one he has tried. We are both on the same South facing hill that keeps frost from developing but who knows. I do love Southern California as far as palm growing but we are inland about 18 miles so a bit cooler in the winter than the coast so still decent for most varieties. I had a really nice Licuala Spinalosa about 4' tall in a pot that I should have moved into the garage but decided to leave it out and by the end of November it was done! I now focus on palms that I know have a good chance and ....I'm out of room anyway , time to watch em grow,  Harry

[bgifford]

A lesson I learned today, and it did not happen on a Cold day, is to secure your palm protection method on all four sides to the ground with tie downs. One of my boxes around my Washingtonia robustas decided today It wanted to go flying. Luckily is 70F today and lows will be well above freezing so that I can fix it before it gets too cold.

 

[jwitt]

Wait.......... .

 

That's it!

[MSX]

If you're using insulation materials to wrap a palm trunk such as mineral wool, fiberglass, PE foam sheets, R-19, whatever, remove those materials as soon as the temperatures return to a safer range. They may be of use during the extreme weather events but after that they create kinda sealed environment around the palm trunk without letting the warm air/sunlight in during daytime warm up, and so the whole protecion starts to act as a refrigerator locking the heavy cold and humid air inside the protection, resulting in ice buildup on the trunk just like in your freezer! This is how the trunk looks like on a very warm and sunny day right after unwrapping from the insulation material (mineral wool).

Edited February 10, 2023 by MSX

[JLM]

Prepare for temperatures a few degrees below the forecast at all times. Dont forget about some of your plants. Sit down before the event and write EVERYTHING down, how you will protect it if needed, and what you need to protect it and how much. This will help not only check off what you can protect with your current supplies but also if you need more. And maybe you wont forget palms lol