Aftermath of a hard freeze and the cold tolerance of subtropicals

we had a hard freeze recently here in 9a, Florida panhandle Jan 16-17 where we hit a low of 20F (less than an hour) and stayed below freezing for about 15 hours and stayed in the mid to mostly upper 20s for probably 10+ hours. i tried to protect my trees that were in ground as well as in the potted trees in two pop up greenhouses. for in ground trees, i used frost cloths, moving blankets, large cardboard boxes, pop up tents and teepee style greenhouses, sometimes i used a combination of these, i.e. tree covered with a frost cloth bag and then teepee greenhouse. for the larger pop up tent greenhouses i lined the insides with layers of heavy duty cardboard but that was not enough as it only provided at best 8-10 degrees F of warmth inside. which means it stayed around freezing in the greenhouse when it was in the low 20s.

i have since assessed my mistakes and put into effect better protection measures (such as better sealing of tents and more insulation) since then when we had more freezing (but not as cold temperatures) later that same week. but the brunt of the damage was already done in the early morning hours on Jan 17.

this is a list of damage to specific young subtropical fruit trees:

potted, in greenhouses:

  • Lula avocado - extensive damage to 75% of tree, most foliage damaged, green trunk turned brown, graft and lower portion of scion still alive
  • Brogdon avocados - one had extensive damage to foliage, trunk is fine, another Brogdon had no damage
  • Fantastic avocados - one tree was flowering and almost all flowers are lost, minor damage to some young leaves and stems, two other Fantastics had no damage
  • Mallika mango - extensive foliage damage, oozing sap, younger once green stems and trunk have turned brown, woody trunk and graft still alive
  • araza (Eugenia stipitata) - dead, had been defoliated prior to freeze from cold temps near freezing earlier in the winter from very brief periods in the mid 30s
  • white sapote (Suebelle variety) - damage to foliage only
  • young dwarf Puerto Rican plantain - turned to mush, not sure if rhizome is alive
  • young dwarf T.R. Hovey papaya - major foliage and green trunk damage, lower woody trunk still alive
  • pitomba (Eugenia luschnathiana) - damage to foliage, still alive
  • pitangatuba (Eugenia neonitida) - damage to foliage, still alive
  • atemoya - major foliage damage, defoliating, still alive
  • cherilata - major foliage damage, defoliating, still alive
  • purple forest guava (Psidium eugeniaefolia) seedlings - extensive damage to foliage, both defoliating, both still alive
  • neem seedling - damage to foliage, alive
  • moringa seedling - damage to foliage and younger stems, alive
  • black surinam cherry seedling - damage to foliage, defoliating, still alive
  • young citruses (lemons, mandarins, tangerines) - minor damage to outermost/terminal leaves

in ground trees:

  • acerola (Barbados) cherry trees - all dead, trunks have split open, had been defoliated prior to freeze from exposure to very brief periods in the low to mid 30s earlier in the winter
  • pink guava trees - splitting of some limbs, only lower trunk still alive, had been defoliated prior to freeze from very brief periods in the low 30s earlier in the winter
  • pitangatuba - extensive foliage damage, defoliating, trunk appears dead
  • Vietnamese pomegranate - an evergreen, damage to all foliage, defoliating, still alive
  • citruses - (lemon, lime, mandarins, tangerines, fingerlime, calamansi, limequats, kumquats) - some defoliation to exterior parts of canopy in older trees, younger ones have more extensive defoliation, otherwise all alive, no damage to kumquats
  • cherry of the Rio Grande trees - damage to terminal leaves only
  • sea grape bushes - extensive foliage damage, trunks and thicker stems still alive
  • natal plum bushes - damage to terminal leaves only
  • dragonfruit cactus - dead
  • purple possum passionfruit vine - dead
  • strawberry guava trees - extensive foliage damage, lower trunks still alive

waiting for spring to see if any that are presumed dead do grow back from the roots…

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sorry to hear all of that. sounds like a tough spot in that you can zone push tropicals most of the time but they’ll get blasted hard for a tony bit once in a blue moon.

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That is discouraging. I hope things make a comeback.

A high tunnel with a heat source would be a big upgrade. I lost fruit year after year to spring freezes. Then I bought a 32x54x16ft greenhouse. Since then only one freeze event when a heater failed on the coldest night of winter. Now I have two heaters and 16 mango trees…!!

On an area basis I get 10x more fruit in the GH than outside.

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on the bright side, most in ground trees are temperate and deciduous and i don’t have to worry about them, in ground evergreen semi-tropicals that were not protected that had no damage - feijoas, loquat, and yerba mate trees. greenhouse plants with no damage - cherimoyas, sapodilla, joey avocados, lemon guava, eugenia repanda. i had two low tunnel greenhouses both against the brick of the house and covered with blankets, all those plants are fine, no damage whatsoever, but too many fruit trees to name here.

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since i’ve only started planting fruit trees in the ground this past spring/summer, it’s going to take a while before i have a warm enough microclimate, trying to give the young fruit trees room to grow is kind of hard when i also want to plant densely, and i am still trying to figure out what grows best here in my area, i definitely need more evergreen trees for protection in the winter since all my temperate deciduous trees are bare and offer nearby subtropicals no protection against the cold and winds on colder than average winter days/nights.

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My fabric and wallpaper printer is in Panama City, Fla. I would go to Fla. to print in the winter. The weather was always horrible. Little sun and 33 degrees. For a beach town, the climate zone is really quirky. Many hurricanes too. Very volatie place to live (for weather).

the mango, papaya, araza, dragonfruit cactus and Lula avocado are definitely dead. the fingerlime is the least hardy of all my citruses and only the trunk is alive. i was surprised to find out after i had dug out the pitangatuba, acerola cherry trees and guavas that they were still green at the bottom of the trunks, too late though, i dug them out and damaged their taproots. except one guava was pushing new growths at the base of the trunk so i left that one in the ground. the passionfruit vine is alive at the very bottom of the vine just above the roots. neem is alive at the base of the trunk, pushing new growth. the sea grapes are alive at the lower trunks. i lost one purple forest guava but the other one is pushing new growth. the surinam cherry which defoliated is pushing new growth. cut the plantain and was still green inside and is growing. white sapote defoliated but is pushing new growth. definitely learning a lot about zone pushing. none of these fruits (except for citruses) should be growing in my zone.

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Instead of digging them up,why not scratch the bark in a few places and check for living tissue?

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i thought about it at the time that i spent more time protecting these than other in ground subtropicals, compared to say strawberry guava, and because acerola, tropical guava and pitangatuba get extensive damage just below freezing whereas strawberry guava can take low 20s, i decided to get rid of them. we go to freezing quite often in the winters, but not too often into the twenties and upper teens. i just have too many plants to take care of, i need ones that can survive here with minimal protection outside. funny thing is all the local nurseries sell tropical guavas and acerola cherry trees so i thought they would do well here. strawberry and lemon guavas will replace them, since they’re more suited for my area. and they taste better too. the one guava that is pushing new growth i’m even hesitant to keep.

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The difference in hardiness between your Lula and Fantastic avocados confirms what I’ve seen about Lula seedling rootstocks at least, which is that they are very cold sensitive. It’s a shame that they are the most popular rootstock in most nurseries in Florida, Texas, and the coast between. Their roots never survive our winters here in Seattle, even 4+ year old ones, while most Mexican type seedlings regrow fine from the roots when the top is killed back.

You’ll probably want Lila instead of Lula, as that one is allegedly pretty hardy (not one I’ve tested yet though).

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yes, i don’t like that they all use Lula rootstocks here. i actually bought the Lula by mistake thinking the label said “Lila” but it was only $40 so I kept it. but also the ground here does not freeze. i got to test several varieties this winter - 3 Fantastics, 2 Joeys, 2 Brogdons, 1 Lula. all potted, all about the same age, all rootstocks about 3/4 inch thickness. the Joeys won, no damage at all. Fantastics had some damage to flowers and young leaves and slightly to young stems, two that were not flowering had less damage than the one that had flowers and younger growth. one Brogdon had no damage and the other one had extensive damage (night and day difference!), on the damaged one all the leaves and younger thinner stems died but the trunk and some thicker laterals are alive. i will also be getting a Poncho, Brazos Belle, Lila and Mexicola Grande, so we will see. thanks for the info!

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The ground here doesn’t really freeze either, other than very very rarely, like once a decade (it did a couple inches deep during our freeze last month that was the start of that polar air dipping down your way, that’s the first time since 2014 it got that cold).

But the soil temperatures here end up being in the 30s and low 40s for a few months straight, and it seems that Lula seedlings can’t handle that.

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our winter here is probably warmer than yours, we usually warm pretty well during the daytime. i will be protecting them better next winter, i’ve learned from my mistakes this past freeze. i noticed the Brodgon leaves don’t have the anise smell like the Joeys and Fantastics but supposedly it is hardy to 18F once mature.

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