Travellar
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Refrigerating my trees

Hi all! been lurking a while, so thanks for all the great advice I've already received.

I have two small trees (Silver maples, I believe) from seedlings. (I'll cut some trimmings this winter, when the leaves fall) I have them under a light on my desk, with a timer. three weeks ago I switched their time from 16 hours of light a day to 10. However, the leaves have not begun to turn yet; ergo I believe they will need 6 weeks in the refrigerator to provide the necessary cold dormancy period.

My question is: will I need to provide light to the refrigerated trees until their leaves fall?

Travellar
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Re: Refrigerating my trees

So I finally took the two maples home and stuck them in a spare mini-fridge Thursday. Watered them on Friday or Saturday and noticed the leaves starting to droop a bit. Checked the soil Sunday, and found it to be rock-hard.

Important note: if using a mini-fridge, ensure temperature is not set so low as to cause the soil to freeze.

My biggest concern is that they are out of sight, out of mind; and I may wind up forgetting about them and have my two die from neglect. :shock: However, I did make a mark on my calendar to bring them back in Nov 22.

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rainbowgardener
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Re: Refrigerating my trees

It would have helped if you had mentioned where you are. I am guessing in the deep South, otherwise you would just leave your trees outside for their cold dormancy.
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Travellar
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Re: Refrigerating my trees

Southern Indiana, so I can't really trust the weather to do anything predictable. (kind of like Illinois, except it's 20 minutes between weather changes instead of 15)

So, the leaves haven't begun changing color yet (didn't expect it this soon) but are really droopy and looking bad. I'm thinking the sudden complete lack of light, or maybe circulating air may be... harmful. Perhaps I'll rig a light inside the mini-fridge. :?

*edit* I should mention, the weather here over the last week has fluctuated between mid to upper 70s, and below 40. Last winter the temps were frequently in the low single digits. That's why I don't want to leave my trees outside; they'll either freeze hard or not get a consistant cold period.

Travellar
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Re: Refrigerating my trees

Latest update on my attempts:
After the first week, I placed an LED puck light in the mini-fridge. (should have done this from the start, LED because of the wide continuous spectrum and low energy draw) After a few days, the leaves recovered somewhat and stopped looking so droopy/wilted. Once the leaves fall, I'll remove the light.
I'm now at three weeks of refrigerated trees, and the leaves have not turned at all. However, the upper leaves now feel dry and brittle, so I expect they may fall soon without turning.
I've been checking the soil perhaps twice a week for moisture. Because it is so cool to the touch, it's much more difficult to gauge. also worth noting that the mini-fridge gets opened daily, so I am not worried about stale air choking my trees.

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applestar
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Re: Refrigerating my trees

Hmmm... I can see you are trying different things and be innovative, but have you considered just leaving them outside until the temperature fall to the point of constant hard freeze? Almost any northern deciduous trees and even seedlings are Absolutely OK until mid-20’s once temps fall below to teens things get a little dicey, and single digits can be harmful. So what you really need to do is find a place outside or in sheltered area of your home that they can be kept protected.

Small trees can be harmed if the roots freeze hard, so it’s a good idea to wrap the roots in their containers and base of the tree. Putting in an insulated container (with drain holes) like old picnic cooler or doubled wooden crate stuffed with insulating material is not a bad idea. But you could just as well bury the pot, cover the tree with hardware cloth (1/2” — 1” would let mice, etc. rodents in) and stuff with dry leaves or straw. All of this is after they have dropped leaves and gone dormant.

Bonsai are often kept in coldframes or under the porch or the house, north side of the house, etc. Covered with leaves and tarp. Apparently, sunny south side of the house which seems like a good idea because it’s warmer is actually not suitable because there is more thaw/freeze cycle (I didn’t know that until a few years ago so I thought I would mention it).

Around late November, before the ground freezes completely, I move in the ones I really don’t trust to the outside mid-winter elements to my unheated garage, where depth of winter temperature falls to low 20’s, killing some of my more sensitive plants, but trees are usually OK. If I really want them to stay above mid-20’s I move them to the insulated side of the garage near the laundry room door, and sometimes cover them on worst nights. I do have a thermometer in the garage, but I also keep buckets and containers of water nearby the plants as a crude temperature indicator — you know, thin ice, thick ice, frozen solid, etc.
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Travellar
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Re: Refrigerating my trees

I've considered the outdoor method, but I have opted against it for this year. The weather is changing too dramatically, and too frequently. Also, I'm an engineer, and like control of my variables. :D

I'm mostly tracking on here to create a sort of record for how this experiment is progressing, and to solicit expert advice on how to pull it off. It's good to hear that 20 degrees may not be a problem, considering I managed to freeze the soil in the first week.

Incidently, assuming all goes well, how long should I expect before my little maples go into spring bloom once I end their winter?

Travellar
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Re: Refrigerating my trees

After six and a half weeks, the maples are back on the desk.
the mini-fridge had fairly high humidity, and watering became unneccessary after about the first week. On the other hand, cold soil is hard to gauge for moisture, so they were a bit drier than expected when I brought them to work. (dumping them out on the floorboards on a turn didn't help, I'm sure) I stopped replacing the batteries in the light inside the fridge after the first two or three weeks.
The leaves never turned or fell, just wilted. tugging gently on one or two showed they were still firmly attached. Perhaps I didn't get the trees into a true dormancy state? I've trimmed, err, pruned the leaves on both trees. (maybe I should have only done one, and kept the other as a control.)
Both trees have been re-positioned in their pots following the tip-over, and thoroughly watered. Both are pliant and apparently still quite alive.

Does anyone have any input on how long until I should expect to see new greenery?

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applestar
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Re: Refrigerating my trees

Do they have buds at leaf nodes? You would see them swell and then open into new leaves. If they are already blooming (age), then I think they might bloom first.
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Travellar
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Re: Refrigerating my trees

No visible buds, but then the old leaves never fell. Both trees are yearlings, so I'm not expecting any blooming.

Travellar
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Re: Refrigerating my trees

So, at the moment, they both look kinda dead.
They went all last week in a relatively dry office environment... without any watering. (not my fault, I was on travel!) The leaf stems have dried and fallen off, (as expected) but they now both look dry and brittle. Well, they've recovered a bit of flexibility this week with some fairly heavy watering. (no pics, office rules) Based on what Applestar says, I think I might luck out and see some signs of life around the first week of January, provided I can go without any more week-long dry spells.

I'm beginning to think I started them in the refrigerator about a month or so too soon. At least I have this year's notes if I want to try again next year, right?

Travellar
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Re: Refrigerating my trees

Final result:
Both trees dead.
Mistakes made:
-Started them too soon, they weren't quite ready for their winter yet
-should not have pulled them from the fridge so soon. they weren't done wintering.
-should not have trimmed the wilted leaves. had I left those alone, I'm now confidant they'd have sprung back into summer form.
-two dry spells: unavoidable, but lethal to these little sprouts. Hard telling just how dry the roots got down in the soil, but this alone may have killed them both had I done everything else right.

Lessons learned:
-refrigerator needs an acceptable light source, preferably on an external power supply, not batteries.
-Start late in the season
-do not let trees go dry in the fridge. It's very easy to misjudge cold soil.

Travellar
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Re: Refrigerating my trees

I know it's late in the season, but I'm thinking of throwing this year's pair of trees into the fridge.

They've stayed on my desk all winter, but since last fall they've essentially stopped growing. One has just one leaf, which has begun wilting, the other has been unchanged over the last few months. no pruning, trimming, or growth.

My plan this time is to water each of them well and refrigerate. After 24-48 hours, I'll take them out, prune all leaves, add a bit more water, and plastic wrap the pots to keep moisture in the soil. then back in the fridge. After 6 weeks, (so, second weekend in April) I'll pull them and bringe them back to work.

Did I miss anything? (Outside is not practicable for me, the weather here is crazy unstable.)

Travellar
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Re: Refrigerating my trees

Trees are back on my office desk, and it appears I did not kill them this year.
Made sure to give them plenty of water this time around, though I didn't do the plastic wrap thing. Actually, I probably over watered them, but they seem okay. There are lively green shoots where I trimmed the leaves, which may just be the stems that never fell.

These next couple of weeks should be interesting.

Travellar
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Re: Refrigerating my trees

those "lively green stems" are quite a bit less lively after a day and a half.

Still we've got a few buds on there, so we'll see what happens.

Travellar
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Re: Refrigerating my trees

Update, On Wednesday of this week (the 15th of May), I finally saw some new growth/buds on one of the two desk trees. Apparently, it's 1 month before new growth appears.

So, I figured out how I CAN refrigerate trees for the winter. (assuming outside weather is not to be trusted.)

On the second tree, I've still got one bright green teardrop shaped bud which hasn't visibly changed since I brought them back in. However, under a magnifying glass, there is one tiny light spot mid stem.

For the second, larger tree, I've got two buds near the base where I had a second branch starting last year. In the top three sections of the tree, where it is still green instead of brown, there are numerous surface specs. I don't believe I've seen these before this week.

all of the "lively green shoots" I observed when I brought them back in have wilted into light tan things. The one at the very top has a bit of light green on it's tip. One at the end of the second branch has a similar light green tip.

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