The Tropical Fruit Forum

I love hearing stories about people succeeding with these cold protection measures, makes me feel there is hope. Did your Mango and avocado trees fruit?

Well a frost and cold night had been predicted and the tropical-fruit-gods themselves must have been angered by my audacity at trying to grow these tropicals because they sent a reckoning.

We had one of the coldest May nights on record, still several weeks out of Winter reaching a shocking -5.4o C (22.28 F). Not only one of the coldest days in May's history, the coldest minimum in over 2 years, with the low of last year's winter not getting this cold (very warm winter though).

Compounding the joke, I had an emergency trip planned interstate. I had hastily draped the plants with some frost cloth without much in the way of anchoring without too much concern as both a mild and still week had been forecast. Obviously on my return (later on the same day of the severe frost and chill) the frost cloth had all but blown off everything.

I am taking stock of damage. Surprisingly most seem as I left them. There are some exceptions. Here are some of the highlight and lowlights.

Bananas; older leaves are quite browned on large trees. Not killed through, they are languishing a slow decline. Younger new shoots still are green and pushing through. Young treees are suffering a little more, one in particular looks troubled.
Babaco: Supposedly one of the hardier of my plants, it has been hit the hardest with many leaves instantly nuked. The damage looks enough to recover from potentially, but only time will tell. I estimate 1/2-3/4 of the plant will defoliate. 
Lychee: Looks to be mildly upset. SOme leaf discolouration and damage, some of which had happened before I went away.
Jaboticaba: One seems a little mad and some leaves have turned purple. Whether dead or just seasonal time will tell. Other Jaboticaba do not seem affected in the same way.
Carambola: Doesnt look grand. It is hard to tell if the frost cloth rubbed some leaves off or if it is suffered from the cold.
Rollinia: I have a few. Some look ok, some look like they are about to give up on life.

Champions at the moment:
White sapote: I have around 5 plants. Several are still pushing bright new green growth as if they were in the tropics, some seedlings (50-100cm tall) are showing some leaf distress, which has been creeping up over a week. Cannot see any acute cold damage from the other night.
Cherimoya: Looks how I left it. That is a win in my book. New growth, no damaged leaves.
Longan: Pushing new growth, cant see any damage.

Most others in the collection very little to report and are still ticking over just fine. Cold is a little insidious though, sometimes the damage comes a day or so later.

And because pictures speak even more words than me;

Babaco in pain



White Sapote no problems



Cherimoya just chilling



Bananas hanging on

1200 old school lights will do a LOT if you can keep them enclosed. That's 12,000W+ of heating at 10w each. It will not be cheap.

Your weather sounds like Vancouver BC where I grew up. While it doesn't seem that cold, it's the constant and frequent cold that never seems to warm that is tough on plants. Your number one issue to worry about is over watering. That has killed more than anything else here in the winter.

Constant frequent cold is right. I think you are spot on with the overwatering too, it is by far my biggest risk and I am really bad watering when they are still damp.

If you're zone pushing and not gonna bring your plants indoors, consider starting many marginal plants from seed. And preferably from varieties that are confirmed or suspected to be most cold hardy. For example, if I were in zone 8a I would try and source as many seeds from avocado varieties Lila, Pancho, Joey, Fantastic and Wilma as possible, and making sure those seeds were not pollinated by any variety less hardy than those. The seedlings may end up being slightly more or less hardy than compared to the parent/s since they will have degrees of genetic variation, but this can come to your advantage. Not to mention, I have noticed seedlings often are simply more tolerant of the cold than their clonal parents. This might have to do with a stronger taproot, I can't say for sure just an observation. For example, this past winter it got to 24F and all 5 of my air layered lychee saplings (brewster sweetheart and mauritius) had major branch splitting, however out of the hundreds of seedling lychees I have lying around unprotected (from those very same varieties), most of them only had very small twig, leaf, and new growth damage. But there are many factors involved.. The seedlings may have simply been out of the wind and much closer to the ground, which near the surface of the ground a bit of contained Earth heat always trickles out, so maybe that heat was just enough to prevent major splitting on those seedlings.. I couldn't say definitively.
But even a little dinky greenhouse or cover will help out greatly. The same winter event stumped all of my in-ground annonas, but I had a couple pots with freshly germinated seedling atemoyas in a TINY greenhouse under some bamboo, and none of them were even phased.
And on the topic of stumping, you will want to prune your marginal plants HARD. The larger the caliper of trunk and branches the MUCH greater chance they have of pulling through a bad winter event. You want the least amount of fresher smooth wood and the most amount of thick bark as possible on all limbs. For example, the same past winter event (24F) re-stumped a few of my in-ground mangos. The mangos had already been stumped twice over 5 years by other bad freeze events, so they have pretty thick caliper stumps. All of their smaller caliper branches that had no real wood were burnt down. However, the few inches of stump that are clearly woody pulled through just fine, and are sprouting new growth (which I will be pruning hard to hopefully get woody too). Same concept as with some of my in-ground annonas..
Also I'd recommend putting those prunings to use by trying to root them up, grafting, or whatever. Might as well..
Some people claim grafting a less hardy variety onto a cold hardy rootstock will increase hardiness of the lesser by a few degrees..
You mentioned jaboticabas. My sabaras were fine at 24F, not even leaf drop on any. I assume they could perhaps be okay even a few degrees lower. No idea how the other jabo varieties would respond to that degree of cold.
There are obscure varieties of annonas from nothern argentina/south brazil and uruguay that will withstand -6C. a.sylvatica, a. emarginata, a. ubatubensis come to mind. There are others too.
There are many fairly cold hardy citrus and avocados if you were interested. Wampee, kei apple, white sapote may be candidates too. feijoa, loquat are bullet proof. surinam cherry also takes the cold, though a couple of mine defoliated around 24F, but no branch damage. Someone on this forum told me his Luc's garcinia and some other garcinias actually withstood below 20F with not much damage. 12-15F was his low. It would be resourceful to not have a bunch of cold hardy plants unnecessarily taking up space in a greenhouse.
You could experiment by rooting cuttings and seeing at exactly what temperature or conditions they defoliate/die/become stumped before subjecting a bigger or prized specimen to those conditions, if you know what I mean. The results may surprise you.. but then again could be misleading because larger woodier plants are often more cold hardy than something like a small experimental cutting anyway..
Also you can try and mound your plants with a bunch of leaves.
And one last thing. I accumulate giant mounds of coffee grounds and have noticed they get VERY hot even in winter. Even small mounds. (significantly hotter quicker than a typical leaf & wood chip pile) Like 150F+.. It would be resourceful to utilize this heat energy, under a tarp and frame or something. You could have a big mound with a sealed tarp over it and pile all your potted plants around the mound still under the tarp. Or have a tarp set up and drag big totes of composting grounds under the tarp with the plants if you don't want the mound of grounds sitting directly on the ground. Just go around town and ask the coffee shops to save their used grounds and start accumulating.

Thank you for typing all that out, really helpful.

I have decided to add some extra layers of protection with frost cloth and 1200 old-school incandescent xmas lights. I hope that will add enough warmth on the codler nights.

I have been reviewing our past few years average temperatures as well. Typically in the coldest months we sit between around negative 1 celsius and +3 celcsius most nights. There is around 3-6 average nights per month going down to -4, and on average 1 or 2 days with lows at -6 or -7 per winter.

I have a very large assortment of plants right now, and I definitely dont want to lose them if it can be avoided, but am prepared for some to go and I can re-use the pots for more tolerant varieties in future.

On the way I also have a bunch of digital wireless thermometers so I can see the temperature protection the pergola is providing.

As a reference I had a potted hass avocado under there last winter and it got through with barely any signs of cold stress.

No room for a greenhouse sadly The property is quite small and on a steep hill. I am moving after this year and will be erecting a more subtropical safe environment then for the ones I love best.

In the meantime I am currently purchasing some incandescent christmas lights to weave up and down the stems to hopefully provide a degree or two.

I expect that some/many of these plants will not get through the winter at all.

In the longer term, I am wanting to find out which of these plants will be able to tolerate my climate using microclimates and can tolerate the colder months with only a small amount of protection. Outside of my favourites, I do not want to have to baby 30-40 plants every winter too much and so want to build in a little bit of an idea of whether it is a total waste of time with even the best microclimate, or if there is some possibility of survival with a minimum of care.

I was considering things like heat mats under pots, and thinking of getting some clear plastic and stapling it to the beams and enclosing the whole patio, and other such treatments, but then thought about this prospect year after year and would rather some less power hungry and labour intensive method. I am happy to enclose and add incandescent Christmas tree lights to the stronger plants that could possibly be planted in ground one day for those winter months, but not 40 plants.

In some ways i think I would like to just satisfy my own curiousity as well. What will survive? What will die first? What will be the unexpected surprise? Will it be a total disaster? If I baby them through winter and 50% get through I will never know if they would have gotten through unassisted, and that will just keep me up at night!

Hello hello all,

My name is Nate and I have a problem. I am totally addicted to purchasing subtropical fruit trees. I have about 20 different varieties from mangos to jaboticaba to anonas to garcinias.

In sunny Australia, the sun is slowly dipping, losing several minutes of sunlight even day, and what is worse approaching winter.

Where I live winters are harsh. By Australian standards it is as bad as we get. By US standards fairly mild for most of the continent, but horrible for subtropical plants, being squarely in a cold zone 9a.

Each year for most of winter we will sit at around -2 to -3 most nights of the week, with several -4 to -5o C days per month typically and one or two below -6. I believe -6 is around 20F.

All my precious little friends are in containers, under a single patio with open sides, and a clear perspex roof to the sky. This offers some protection from frost, but only takes the edge off the cold.

And so, being only 2 months into Autumn and with multiple nights already below -2o C, I need comfort and friends. Anyone here done this successfully?

Tell me your tales and whisper me your secrets.