Bonsai in fridge

[datminh221]

Hi! I decided to pick up 2 JWP but then realized they need a winter dormancy to survive long term. I live in a tropical area so there’s no winter, lowest it gets is 65F (18C). I read around and see some use fridge but no “long term” success yet. I’m gonna give it a shot with a mini fridge to control the temperature around 33-40F (1-5C) and humidity. I still haven’t found a clear answer:
1) is the temperature above enough to kick the tree into dormancy?
2) what humidity level should be maintained to not desecrate the foliage and roots?
3) is light needed? At what temperature will light no longer be required? I heard that when winter dormancy kicks in, light is no longer needed.

If anyone has any experience or stories to share, please do! Thanks yall

 

[penumbra]

1) is the temperature above enough to kick the tree into dormancy?

Yes

2) what humidity level should be maintained to not desecrate the foliage and roots?

50% and above

3) is light needed? At what temperature will light no longer be required? I heard that when winter dormancy kicks in, light is no longer needed.

Dormant maple needs no light, it has no leaves.

 

[Shibui]

Dormant maple needs no light, it has no leaves.

The question seems to refer to pines - evergreen???????

 

[Paradox]

I've kept pines in a dark garage or coldframe where they got no direct light for weeks and all were fine.

I'd be more concerned with humidity and making sure that temperature stays below 40F

 

[Gabler]

Knowing your approximate location would help. You should add it to your profile to get more specific advice.

 

[namnhi]

Fail from the start. Stop trying out of zone trees.

 

[NaoTK]

I do it all the time, should work fine. Wait, I'm thinking of beer

 

[rockm]

FWIW, temperature is only a single factor in dormancy. Thinking it is the only thing misses about 90 percent of what is actually going on. As far as people using fridges to "induce" dormancy in tropical locales, the more important question is how long they've been doing it and asking to see their trees...

and FWIW, putting ice on the surface of a bonsai won't produce dormancy. It may produce root shock, but not real dormancy...

 

[MaciekA]

OP, your core motivation to place a JWP in a fridge is presumably motivated by the widespread notion within bonsai that "these trees need dormancy".

But to understand why putting a JWP in a fridge is probably not helpful, it's worth thinking about why these trees "need dormancy" in the first place.

A year of a JWP's life:

1. Temperate Spring/Summer: push out candles, push out needles, open bundles and continue to elongate into late summer. Stored sugars are moving into foliage.
2. September: Photoperiod (daylight length) starts to dramatically reduce. Temperatures begin to drop.
3. Step #2 triggers and hastens a switch to vascular growth. The tree stops directing sugars (whether stored or newly-produced) towards foliage production/elongation. It now begins to instead distribute newly-produced sugars (from autumn sun) throughout the vascular system, which manifests as thickening. This is the "main event" of dormancy because it is an energy accumulation event triggered by temperate climate seasonal shifts. That accumulated energy will be used to fuel next spring's flush and to build up a reserve for emergencies.
4. Temperatures dip below 7C. Photosynthesis doesn't work well at these temperatures and water will eventually freeze, so consuming the stored sugars would be pointless. The tree is therefore mostly dormant until Feb/March/April depending on latitude/elevation/proximity to oceans. The point of this phase is to withhold consumption of the starch collected during step 3 so that it is available for later. The point is to not arrive at spring with an empty battery.
5. Temperatures come back up in spring. The stored starch is liberated from the wood and used to fuel the spring flush.
6. GOTO 1

The fridge is step 4. But if a JWP skips steps 2 & 3, then the big question is whether a JWP will "fill up the sugar battery" in the first place.

In bonsai culture, the idea that trees burn through their reserves when skipping winter is mostly informed folklore. But in tree science -- for example, siberian larch plantations in Iceland -- trees that burn through their winter reserves by waking up during winter heat spells are known to hit a wall and quickly succumb to pests and pathogens due to weakness (emptied out reserves -> smaller , weaker spring flush -> easier target for biotic and abiotic factors). So it also follows that never having accumulated that sugar in the first place (by skipping the ~3 months of autumn) would have the same effect.

If I were growing a JWP in the tropics, I would not bother with a fridge. I wouldn't try to even induce dormancy. I would focus on two things:

1. Look to what the entire accumulation/dormancy game actually accomplishes (i.e. plentiful starch reserves) and try to replicate that, forget about just the one part of the dormancy cycle (the cold part): Let the tree physically accumulate and visibly store a lot of sugar into the wood. Don't assume tropical vigor comes with no strings attached. Grow very long extensions. I would let shoots / branch lines run for much longer than I would in a temperate climate, to ensure that one way or another, sugar produced in the sacrificial parts of these branches is noticeably accumulating elsewhere in the tree. I would want to see proof that the tree is physically lining the wood with extra thickness. I need that thickness for future flushes, not just taper.
2. Start with inorganic media from the beginning because tropical = humid and hot. Reference: pumice, lava. Focus on air in the roots. Trees don't eat dirt.

JWP can handle heat and humidity, Japan is a humid and often warm place. But what JWP can't handle is having its roots asphyxiated or being mercilessly stripmined of its energy reserves in a pathological manner while pursuing an instant-bonsai strategy. Wire branches down, let them extend for miles, prove that it survives first.

 

[rockm]

Day lengths begin to decline at the Summer Solstice in June, not in September. The autumnal equinox is in September, which means equal hours of day and night. Sunshine hours continue to decline after the equinox until the Winter Solstice in Dec. That gradual decline (3 minutes per day, depending on your latitude between the Summer Solstice and the Autumnal Equinox) is a big part of inducing dormancy in deciduous temperate zone trees.

 

[MaciekA]

Day lengths begin to decline at the Summer Solstice in June, not in September. The autumnal equinox is in September, which means equal hours of day and night. Sunshine hours continue to decline after the equinox until the Winter Solstice in Dec. That gradual decline (3 minutes per day, depending on your latitude between the Summer Solstice and the Autumnal Equinox) is a big part of inducing dormancy in deciduous temperate zone trees.

Fair and thanks for the detail. As a person who wakes up at 4AM and goes for a run, similar to you, I too have a table of how many sunlight minutes we lose every single day between June 21st and onwards seared onto my brain. My claim however is not that the reduction in day length begins in September.

My claim (supported by others like Ryan Neil) is that the reduction in day length September starts to become very noticeable and rapid both to humans and trees. This is when the rollcoaster ride on the annual photoperiod sine wave is steepest, having its steepest slope at equinox. And relevant to this thread is that this is when needle elongation in various pines starts to plummet or cease, and when water consumption shifts noticeably, etc. Your decandled shoots on JBP slow greatly during this time. The "second growth" shoots that sometimes appear on things like korean pine, lodgepole, JWP, scots pine, etc cease elongating during this time (suggesting behavior is global to pinus since that covers strobus subsection, pinus subsection, and trifoliae subsection).

At least some trees in tropical places do still notice this change even if the amplitude of that photoperiod change is squashed from their point of view, and organize their growth behavior around the peaks and valleys. This I know from a U of Hawaii researcher who told me a couple years back that plenty of species on the islands react to photoperiod. This is why IMO the right strategy here isn't to fixate on fridges but on the ultimate effect of the dormancy tee-up and dormancy itself, which is to ultimately ensure there is plenty of "dry powder" available in the form of stored starch when the next flush is imminent. I posed the skipping of the photoperiod trigger as a question, not a claim, because I know that in much of the tropics, it is still there, and detectable by plants. The main question for JWP is the degree to which this'll induce autumn-like hoarding in the tropics. If it doesn't, I say just keep lengthening, because lengthening causes thickening upstream of the tips, and thickening is suggestive of stored energy, which is that dry powder.

 

[penumbra]

The question seems to refer to pines - evergreen???????

I screwed the pooch on this one. I was think of Japanese maples. As to Japanese White Pine, if you are living in a hot climate they may fail regardless.

 

[dbonsaiw]

Trees going dormant is an extended process - one that is very different than humans simply going to sleep. As has been pointed out, this process begins back in the summer and the trees slowly acclimate to the changing temps/day light. Sugars need to find their way into the tree for storage. Trees are hardening off, using energy on root growth, filling inter and intra cellular spaces to buffer against the freeze that is coming. There is a great deal going on. Deciduous trees that go directly from active growth to dormancy are doomed to failure. In fact, I have purchased trees too late in the season from areas further south than me and the trees died because they didn't have sufficient dormancy prep - they froze to death.

The bad news is that it is much easier to keep tropicals indoors in my zone for the winter than it is for you to keep deciduous trees indoors in your zone for dormancy. I just need some lights and keep one eye on the humidity. It's not as good as outdoors, but does the trick well enough. You, on the other hand, need to ease the trees into dormancy for an extended period and then keep it dormant while maintaining proper humidity. I have no idea how to artificially ease a tree into dormancy, nor how to control humidity in a fridge. Mach5 has a good thread on his experience keeping a JM in the fridge (hint: it didn't go well and I would consider him an expert).

 

[rockm]

Fair and thanks for the detail. As a person who wakes up at 4AM and goes for a run, similar to you, I too have a table of how many sunlight minutes we lose every single day between June 21st and onwards seared onto my brain. My claim however is not that the reduction in day length begins in September.

My claim (supported by others like Ryan Neil) is that the reduction in day length September starts to become very noticeable and rapid both to humans and trees. This is when the rollcoaster ride on the annual photoperiod sine wave is steepest, having its steepest slope at equinox. And relevant to this thread is that this is when needle elongation in various pines starts to plummet or cease, and when water consumption shifts noticeably, etc. Your decandled shoots on JBP slow greatly during this time. The "second growth" shoots that sometimes appear on things like korean pine, lodgepole, JWP, scots pine, etc cease elongating during this time (suggesting behavior is global to pinus since that covers strobus subsection, pinus subsection, and trifoliae subsection).

At least some trees in tropical places do still notice this change even if the amplitude of that photoperiod change is squashed from their point of view, and organize their growth behavior around the peaks and valleys. This I know from a U of Hawaii researcher who told me a couple years back that plenty of species on the islands react to photoperiod. This is why IMO the right strategy here isn't to fixate on fridges but on the ultimate effect of the dormancy tee-up and dormancy itself, which is to ultimately ensure there is plenty of "dry powder" available in the form of stored starch when the next flush is imminent. I posed the skipping of the photoperiod trigger as a question, not a claim, because I know that in much of the tropics, it is still there, and detectable by plants. The main question for JWP is the degree to which this'll induce autumn-like hoarding in the tropics. If it doesn't, I say just keep lengthening, because lengthening causes thickening upstream of the tips, and thickening is suggestive of stored energy, which is that dry powder.

The pace of day shortening actually SLOWS a bit after the Autumnal Equinox, depending on your latitude.

My point is that just because you NOTICE the days are shorter in September, doesn't mean much. The pace begins almost three months earlier. This is what most people miss about the process of dormancy. Plants are "signalled" a lot earlier than most people think to shift operations. The processes intensify in the fall with the onset of colder temps, but it has been going on for some time. That's why I'm always skeptical of just plunking a maple or pine in a refrigerator and calling it dormancy.

I have also heard that Japanese White Pine has a very bad time growing in more southerly or tropical locations because of high heat and humidity, not necessarily lack of winter dormancy. Don't know if that's true, but ask folks who have had the species in places like Texas and La....

 

[Kevin1968]

Wouldn't the fridge cause oxygen deprivation? A fridge is designed to recirculate the air inside and not allow fresh air in or out, till the door is open and closed. This would be a dibble edge sword as you would have to keep opening and closing the door, the fridge will never get a low enough temperature for the tree. Air as well as water gets stagnate.

 

[Wires_Guy_wires]

In theory, it can work. In practice, it's difficult.

First thing we need to account for is shortening of daylight length, that can be done with a timer.
Second thing is the gradual drop in temperature, that can be done by running the fridge on a timer.
Once dormancy sets in, it's dormant. It doesn't require much.
However, getting a full dormancy done well, requires the reverse of operations as well; daylight lengthening and temperature fluctuations.
You'd need air circulation, which is quite difficult if it's a closed system.

Some plants have more than 12 proteins that are essentially biological calendars; they keep track of time, they activate when temperatures drop or increase, and they require both a build up as well as maintenance.

I think bonsai is cool and all, but setting up a system like this takes a couple years of tweaking and adjustments. Sometimes the effects of imperfect dormancy can take years to show. If you want to spend a decade tweaking the system while losing a couple plants: AWESOME! You now made a device that the super rich would want for sure.
Other than that.. You might be better off getting other plants that look and behave similar. In all honesty, I think this is a wheel that could use some re-invention. But I'm not going to be the one that does it, mainly because I have winters.

 

[rockm]

Wouldn't the fridge cause oxygen deprivation? A fridge is designed to recirculate the air inside and not allow fresh air in or out, till the door is open and closed. This would be a dibble edge sword as you would have to keep opening and closing the door, the fridge will never get a low enough temperature for the tree. Air as well as water gets stagnate.

Trees don't really need oxygen as much as animals do, but yeah being sealed in an air tight container presents a number of problems. gas exchange being one. The smaller the fridge the more susceptible to rapid temperature changes. Dry air is another. Refrigerators are designed to remove moisture from the air inside--the cooler the air, the less moisture it can carry. Dry air desiccates plants--what happens to vegetables left too long in the crisper? They lose their crispness and turned wrinkly and/or limp.

 

[Kevin1968]

@rockm
Thank you, I just learned something.

 

[Paradox]

Day lengths begin to decline at the Summer Solstice in June, not in September. The autumnal equinox is in September, which means equal hours of day and night. Sunshine hours continue to decline after the equinox until the Winter Solstice in Dec. That gradual decline (3 minutes per day, depending on your latitude between the Summer Solstice and the Autumnal Equinox) is a big part of inducing dormancy in deciduous temperate zone trees.

yea this would also be a big concern of mine. Just shoving the tree into the fridge in November for example from otherwise warm temperatures with no acclimatization kind of ignores the whole physiology and seasonal rhythm of the tree. Its not something that can be simulated by just putting the tree in fridge.

Honestly I think the OP should find someone in a location that can grow the tree and sell/give the trees to them because this is probably going to be a futile effort.

 

[River's Edge]

Hi! I decided to pick up 2 JWP but then realized they need a winter dormancy to survive long term. I live in a tropical area so there’s no winter, lowest it gets is 65F (18C). I read around and see some use fridge but no “long term” success yet. I’m gonna give it a shot with a mini fridge to control the temperature around 33-40F (1-5C) and humidity. I still haven’t found a clear answer:
1) is the temperature above enough to kick the tree into dormancy?
2) what humidity level should be maintained to not desecrate the foliage and roots?
3) is light needed? At what temperature will light no longer be required? I heard that when winter dormancy kicks in, light is no longer needed.

If anyone has any experience or stories to share, please do! Thanks yall

Before this discussion goes any further, what do I do with the beer, wine and Clonex? The small fridges are meant for Clonex, right?