Anyone here really pushing the zones hard? (maybe even successfully?!)

[naikii]

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.

[shpaz]

I think it's better to make small heated green house if you can.

[naikii]

I wish this were a possibility!

[shpaz]

Since its a patio, what about trying to close off the slides a bit to stop strong cold winds partially then adding a small heater at night?

[fruitnut1944]

+1 on the greenhouse. Anything covered but bright light with a heater is a greenhouse. Mine works wonders in a very harsh 7b climate.

[Plantinyum]

I am also in zone 7 ,bunno a or b ....I grew  alot of tropical fruit plants without a greenhouse,that is cherimoya ,carambola ,dragonfruit ,passifloras ,guavas and so on. They were containerised till this year, since in fall I build a greenhouse and have planted most of my tenders in it in the ground, It will be heated in winter and I will be posting updates when the cold hits.
 I really think the gh is a game changer since this winter without heating the lowest temp there was -7 which is zone 9 I believe .

[brian]

Yes, heated greenhouse is the way to go.  Next best is container growing and moving plants inside when it is too cold. 

[K-Rimes]

I'm in 9b and growing a lot of 10a plants. No problem at all when you have even an unheated greenhouse that gets sun during the day. I saw 26f outside here this winter and the GH stayed around 39f with just a small heater running sporadically in the night.

Greenhouse greenhouse GREENHOUSE. Insulate it as best you can with the double wall panels and bury it a foot or two. Make it double as big as you think. I wish mine were bigger. It's 24x10

[naikii]

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!

[K-Rimes]

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!

I was much like you when I started out and had some successes my first year keeping things alive with frost cloth and incandescent "hipster" lights strung around through my dragonfruit and all the smaller stuff sprinkled in between in the enclosure. I started to get aggressive and buy things knowing they were edgy and maybe wouldn't make it but I was confident in my technique that worked the year before. I lost a lot of really nice plants two years ago and smartened up.

A lot of the time, even if they survive, they're never quite the same and die a slow death. I had a beauty of a grafted mango tree that survived three 9b winters but finally succumbed this last year and died to the union. I will not chase mangoes again.

This year I parked a bunch of plants that wouldn't fit inside the greenhouse (since it was so full) in my landlord's garage and they did awesome. I just put them in there for the 5 coldest days of the year and then pulled them out when the frost risk was gone. Totally paid off. They are firing up better than ever. If you have a big garage or storage shed, that could work too.

Anyway, I'm kind of rambling but the point I'm trying to make is be smart about it and you'll have more success and it'll cost you less money and stress. You won't see soursops, rollinias, mangoes, or mangosteens around my 9b zone for good reason.

[brian]

I agree... if you are using containers and you can't keep them actively growing through the winter you might as well just store them dormant someplace like a basement or garage. 

[naikii]

I was much like you when I started out and had some successes my first year keeping things alive with frost cloth and incandescent "hipster" lights strung around through my dragonfruit and all the smaller stuff sprinkled in between in the enclosure. I started to get aggressive and buy things knowing they were edgy and maybe wouldn't make it but I was confident in my technique that worked the year before. I lost a lot of really nice plants two years ago and smartened up.

It's funny, one of the stores I order a lot from says this in their description;

Use the item specifications above taking particular note of Climate and Frost Tolerance to make your decision. For some reason the personality of people who like to grow fruit trees favours the bold and people from VIC like to grow Subtropical - Tropical plants even though they are more suited to Temperate - Subtropical. This also works the other way people in QLD like to grow Temperate plants when they should be growing Suptropical - Tropical plants. There is nothing wrong with this but you must accept that you are taking a risk and you should research techniques that will minimise this risk.

I have to chuckle because it is so accurate. Your average gardnener heads down to their local nursery and buys a local plant that they know will perform well in their area.

Gardeners like us, who spend all their days on the internet researching new and interesting plants, who read through forums and blogs and who are always looking for the next possible thing are another breed. We are not satisfied with the average common varieties available at the big box store. Not satisified with the common fruits that grow easily in our regions. Not satisfied with a single cultivar. We feel the need to collect it all, and enjoy our hobby and push the limits to their max.

It is only when nature has punished our audacity and confidence by taking from us all our favourite plants, killed every stem to the ground and turned every leaf black that we either double down and invest more money and resources to try even harder, or resign ourselves to acceptance

One day I may learn that I cannot grow rollinias in a location that gets down to -7o C most years, or I will succeed, and until I am taught that lesson personally, or succeed, I will keep trying!

[K-Rimes]

I killed a beautiful flowering Rollinia last year and its death will haunt me for the rest of my life, probably. For reference, it never hit freezing here and I bagged the tree with incandescent lights.

I applaud your enthusiasm, just don't go crazy blowing money on plants that simply will die a sad death.

There is zone pushing and then there is killing plants for sport.

[CarolinaZone]

Yep, I'm in Zone 7a/b and I am doing in ground citrus. I am doing mangos and guava in an unheated greenhouse.

 

[Plantinyum]

Yep, I'm in Zone 7a/b and I am doing in ground citrus. I am doing mangos and guava in an unheated greenhouse.

in an unheated greenhouse?? What are your general lows in winter outside and inside of the gh. What is the lowest temp that u have experienced in the gh , thank u :-)

[K-Rimes]

Yep, I'm in Zone 7a/b and I am doing in ground citrus. I am doing mangos and guava in an unheated greenhouse.

A greenhouse is the move 100%. I get a solid 10f of protection inside the gh with just a few string lights. I get lows of 26-28f annually, but that translates to a comparably balmy 36-38f in the GH - perfect for chasing sub-tropicals.

I do like to push the zone a bit, I just think it's really hard if not impossible without a greenhouse. I recommend finding space for it OP!

[Tropical Bay Area]

How much protection does an unheated greenhouse usualLy offer?

[K-Rimes]

How much protection does an unheated greenhouse usualLy offer?

Depends deeply on build quality, insulation and amount of sun it gets

[brian]

Wouldn't an unheated greenhouse be vulnerable to a string of cold cloudy days?  At some point the retained heat is all going to be gone if it isn't being warmed by the sun.

I imagine it would help extend the growing season considerably, but I would plan on some kind of emergency heat.  Those propane heater attachments work really well.  I used them the first winter when my greenhouse heat wasn't ready yet.

[fruitnut1944]

My greenhouse if unheated retains heat about one hour to at most a couple of hours. It's large, tight, and has a double layer inflated woven poly covering. The covering has heat retaining properties. But without heat the temperature inside at night closely follows outside. The only exception is a few degrees warmer inside when there is heavy cloud cover.

I do think there is some protection inside vs outside. But in 15 yrs mine has never been below 33F so I can't say if there would be less freeze damage inside vs outside at the same temperature. I say some protection because I've heard that often. But you never know what people are dealing with. One guy said his stayed 10-15 F warmer than outside without heat. Then several posts later said well it is open to a large insulated attached garage. What does that tell you, nothing about an unheated greenhouse.

I'm very skeptical of anyone who says their unheated greenhouse stays warmer than outside. For one thing how are they measuring temperature? It's not easy to get both inside and outside measured equally well. And just the physics of it says that it won't stay much warmer for very long. The R values of greenhouse coverings are about equal to wearing a T shirt in a blizzard. I've had 15 yrs with good thermometers to decide mine doesn't hold much heat very long. Last night mine fell to 47 with outside at 47.

[K-Rimes]

These Bluetooth thermometers are +-1f. The proof is here. On average 5-8f of improvement. Of note and this is very important this greenhouse gets blasted as the length is 24’ long and the length is south facing. What is excellent is the average temp being so much higher. Plants really slow down below 40f.

My greenhouse is on an asphalt driveway which acts as a heat sync and the greenhouse is absolutely 100% full so lots of mass to warm up.

[fruitnut1944]

These Bluetooth thermometers are +-1f. The proof is here. On average 5-8f of improvement. Of note and this is very important this greenhouse gets blasted as the length is 24’ long and the length is south facing. What is excellent is the average temp being so much higher. Plants really slow down below 40f.

My greenhouse is on an asphalt driveway which acts as a heat sync and the greenhouse is absolutely 100% full so lots of mass to warm up.

Is that with no heat and no ventilation? Outside you show 77 to 33F over 4-5 months. We have 44F temperature swings many days and averaged 55F each week in one winter I tracked. This winter 84 to 4F outside. In the greenhouse without heat or ventilation that would be ~130 to ~6F. I have seen +6F inside with heavy cloud cover. We have very little cloud cover in winter, Santa Barbara has a lot.

[K-Rimes]

The GH has gable fans that I have programmed to turn on at 86f - previously I had them set to 90f (during winter, and they hardly came on). I am at 2200' feet above the sea and rarely if ever have cloud cover - I am well above the marine layer from the ocean. I would wager we have fewer than 20 days of cloud cover per year and only 5-8 days of rain. It's high desert, basically. I regularly see 50f swings when the sun is out in the winter 40f ambient up to 90f when the sun is beaming.

For sure if you have cloud cover or trees that obscure your greenhouse when the sun is low on the horizon, the greenhouse will not provide much if any benefit. The only way it really works is if it gets hot inside, all the mass inside or the ground itself heats up, and then it slowly dissipates over night (and the gh is relatively sealed / insulated). I chopped down a ton of oak arms that obscured the gh this year so I expect it will be even better this winter.

I did have 300w of incandescent "hipster" lights, but I really don't think those make a big difference. On days that the power was out (this happens often in my rural location) the temps were basically the same. It just made it look nice at night.

[850FL]

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.

[TheGivingTree]

This is great info. I am in my second year of collecting fruit trees and am now growing most rare zone pushers from seed. Working on solutions for keeping them warm, will be setting up two small greenhouses as well as putting wooden posts around the in-ground trees and wrapping with plastic.

[naikii]

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.

[Ulfr]

Yeah you really need a heat source or thicker coverings than frost cloth down there. I did some tests with data loggers and frost cloth and found while it was enough up here, it only kept them slightly warmer.

https://m.youtube.com/watch?v=x5Pf_n86cZI&t=3s

[K-Rimes]

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.

[naikii]

Yeah you really need a heat source or thicker coverings than frost cloth down there. I did some tests with data loggers and frost cloth and found while it was enough up here, it only kept them slightly warmer.

https://m.youtube.com/watch?v=x5Pf_n86cZI&t=3s

Firstly, great video, and good to see another Aussie on here. I love data driven information that shows empirically how much of a difference cold measueres make in the wild.

Secondly I thought that the difference provided by your (much thicker) frost cloth was quite sigificant. I bet in colder temperatures this difference would be even more pronounced.

Unlike your trees mine are on concrete pavers, with some right up against the brick wall of the house. These should act as a heat sink much like the water container with your jackfruit. The pots themselves are mainly black and should also absorb some heat during the day and hopefully radiate through the night. 

Although the frost cloth is quite thin, I have purchase 4 strands of 300 xmas bulbs which I will wrap around the pots and stems, and should radiate even more heat upwards overnight.

Here is an idea of what I have undercover https://www.youtube.com/watch?v=zVRIRDRf8FU, not quite as well put together as your own, but we do what we can!

[naikii]

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.

[CarolinaZone]

Yep, I'm in Zone 7a/b and I am doing in ground citrus. I am doing mangos and guava in an unheated greenhouse.

in an unheated greenhouse?? What are your general lows in winter outside and inside of the gh. What is the lowest temp that u have experienced in the gh , thank u :-)

To be honest, I didn't collect that data this year. Sorry.

[Ulfr]

Yeah you really need a heat source or thicker coverings than frost cloth down there. I did some tests with data loggers and frost cloth and found while it was enough up here, it only kept them slightly warmer.

https://m.youtube.com/watch?v=x5Pf_n86cZI&t=3s

Firstly, great video, and good to see another Aussie on here. I love data driven information that shows empirically how much of a difference cold measueres make in the wild.

Secondly I thought that the difference provided by your (much thicker) frost cloth was quite sigificant. I bet in colder temperatures this difference would be even more pronounced.

Unlike your trees mine are on concrete pavers, with some right up against the brick wall of the house. These should act as a heat sink much like the water container with your jackfruit. The pots themselves are mainly black and should also absorb some heat during the day and hopefully radiate through the night. 

Although the frost cloth is quite thin, I have purchase 4 strands of 300 xmas bulbs which I will wrap around the pots and stems, and should radiate even more heat upwards overnight.

Here is an idea of what I have undercover https://www.youtube.com/watch?v=zVRIRDRf8FU, not quite as well put together as your own, but we do what we can!

Thanks for the kind words. Really keen to see how it goes with your trees. You are certainly right that the concrete/brick walls will hold heat, a lot more than my barrels of water. You might indeed get enough buffer to avoid damage in the lows at which point (as others said) it’s the lack of heat during the day that’s the challenge.

[850FL]

Also a few more factors at play- higher humidity seems to worsen the effects of freezes. And plants established in the ground often seem to do better than plants on the ground in pots (even if many survive they eventually may need big bulky pots to produce a decent amount of fruit anyway).
Also sometimes frost coverings may trap too much heat and end up conversely killing your plants.. especially if say it was 35 degrees F and then the sun came up and warmed inside the covering to 90 degrees- thats almost a 60 degree temp swing in a short period. The point is just monitor the covering when the sun gets more intense.
And even just a single drop to -6 or -7C can mean disaster when certain plants were just fine during -2 and -3C frosts. You had a sapling hass survive -6 or -7C with barely any stress? I had probably 10 seedling/sapling hass and ALL were stumped when it got to -7C.. one was even 8ft tall and not lanky either!

[naikii]

Also a few more factors at play- higher humidity seems to worsen the effects of freezes. And plants established in the ground often seem to do better than plants on the ground in pots (even if many survive they eventually may need big bulky pots to produce a decent amount of fruit anyway).
Also sometimes frost coverings may trap too much heat and end up conversely killing your plants.. especially if say it was 35 degrees F and then the sun came up and warmed inside the covering to 90 degrees- thats almost a 60 degree temp swing in a short period. The point is just monitor the covering when the sun gets more intense.
And even just a single drop to -6 or -7C can mean disaster when certain plants were just fine during -2 and -3C frosts. You had a sapling hass survive -6 or -7C with barely any stress? I had probably 10 seedling/sapling hass and ALL were stumped when it got to -7C.. one was even 8ft tall and not lanky either!

The Hass I didn't expect to survive actually. I bought it as a duo type A and B, with a Bacon. I only really wanted the Bacon, but the special was cheaper than buying the Bacon alone. I put it in a approximately 34L pot and didn't do anything except move it under cover. Surprisingly it didn't seem to be affected at all.

The Bacon I put in a sheltered position in the garden, and it pulled through with minor leaf damage. It was however a warm winter last year.

I've had to go interstate for a week right now and watching the weather we have a -4oC morning predicted the day we get back. I had hastily draped some frost cloth just in case before I left, but barely secured. I had to run at very late notice.

The containers that these trees are all in are general quite large, 30L and 55L mainly. Some 85L and a couple in 10L containers.

I hope I'm not in for a shock when I return after this cold morning, no chance to put the Christmas lights up yet.

[CarolinaZone]

I forgot to mention I have an in ground strawberry guava. I used minimal protection on this other than covering the base with leaves. 3gal planted last year in the spring. The exposed branches are pushing growth now.

[850FL]

I forgot to mention I have an in ground strawberry guava. I used minimal protection on this other than covering the base with leaves. 3gal planted last year in the spring. The exposed branches are pushing growth now.

Which strawberry guava? P. cattleyanum?

[CarolinaZone]

As far as I know P. cattleyanum is the only strawberry guava. Is there another plant called that?

[brian]

I think the yellow type is psidium littorale, even though it it basically identical to the red kind other than the fruit color/taste

[CarolinaZone]

Ok. Well here's where it get's interesting. To be honest I am not sure but I Suspect it is a cattleyanum var. littorale. I had bought several the year before last that were marked incorrectly as red cattley guava P. cattleyanum var. cattleyanum. Later last year when one of them fruited it was yellow. I suspect the one in ground is from that batch.  It defoliated over the winter and some of the branch tips have been damaged. I plant to pull back the mulch and fertilize heavily. Only the new growth seems to be damaged. The woody mature growth seems ok. The issue I see is the two flowering cycles. Cycle one seems to start in October and cycle two seems to start in  February. Cycle one is too late for the fruit to mature before it get s too cold. Cycle two ( this based on the indoor specimens) would be two cold for the fruit to appear outdoors.

[naikii]

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

[naikii]

Since returning I have also set up some wireless sensors to monitor the cold protection provided. My goal is to map out the hot and spot areas and use them to help get through the next few months and to test different cold protection methods.

I had additionally purchased 1200 incandescent christmas lights which I dutifully strung throughout all the plants, only to have the cheap damn things all die after several hours. Now I have the fun job of removing all those lights and sending them back.

Over time I will post how much protection each of the areas under the patio provides. I have attached a crude map to show the location of each sensor.



I have 5 in total;

• Sensor 1, towards middle of patio with no frost cloth, and a decent amount of brick wall adjacent as well as eaves of house. In an Achacha Pot resting on soil.
• Sensor 2, towards the edge of the patio with a frost cloth covering, no walls in close proximity. In a White Sapote pot resting on soil
• Sensor 3, towards the edge of the patio with no frost cloth covering, against a wall and under eave. In a Hass avocado pot resting on soil.
• Sensor 4, control sensor outside of the patio area away from walls of hosue. In a very large (300L pot) with a Tangello.
• Sensor 5, soil temperature and moisture under frost cloth. In Cherimoya pot.

The patio provides several degrees of protection.

Local weather is being reported now as: 12.4o C. Current reported temperatures from sensor readings are;

• Sensor 1, 14.0o C.
• Sensor 2, 13.0o C 
• Sensor 3, 10.7o C.
• Sensor 4, 6.7o C.   
• Sensor 5, 7.7o C.   

The overnight minimum was reported as -3.1o C. The minimums recorded from the sensors was;

• Sensor 1, (null, needed resetting).
• Sensor 2, 1.0o C 
• Sensor 3, 0.1o C.
• Sensor 4, -1.3o C.
• Sensor 5, 4.7o C.   

Current soil moisture is at 47%.

[Fygee]

Similar story in Las Vegas where I live.

Winter temps tend to be the death knell for a lot of tropicals/subtropicals. I either bring the smaller ones indoors, or protect them with burlap in a corner that stays just a bit warmer than the rest of my yard.

Some of my trees like my avocados and mangoes handle winter unprotected just fine now, primarily due to our winters being warmer than usual lately. That said, we had a freak snowstorm this year that took out my Coconut Cream mango tree that I'm very sad about. Weirdly enough, it wasn't the snow, but the melted snow waterlogged it and it got root rot.

Anyways, it can be done, but protection and variety selection are very important.

[naikii]

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?