Shohin Bonsai Winter Care


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Well I have a Acer Palmatum 'Kotohime' bonsai tree and was wondering what i should do with it this winter i live in Michigan and it gets in the negatives here.
Do you have an unheated garage or porch? You could put the tree in a styrofoam type cooler and mulch all around with leaves then put it in the garage or porch. If you do this, be careful when watering that no standing water is left in the cooler.
A few questions first:
What are your options? (ie. do you have an unheated garage, porch or shed? etc.)
Was the tree repotted this past year? Any idea of it's history - what previous owner did in winter?

john romano
I have a shed, this summer it was repotted, it came from ca, i do not know.
Kotohime in nature are hardy to zone 6. Most of Michigan is zone 5 and 4. And those are only for plants in the ground, not in shallow pots. This being a shohin makes it's hardiness even less. I think it would be OK down to 20 degrees and maybe less - without wind. The shed may be a bit of a risk. If you had a cold room in the house - an insulated cold room in the basement, for instance - that might be better. Because it can also be a bit warmer in winter (30's, 40's, etc.) as those in parts of CA. IF the shed is the only option, I would put it in some kind of insulated box/styrofoam cooler and maybe a light bulb on at night near the pot base / or a heat pad at night (you can put it on a timer). One other option I can think of is to find a local bonsai nursery or other nursery who could keep it in a cold greenhouse for you. Good luck.
I read some ware the i can winter my tree in the refrigerator for the winter.
IF THE TREE IS ALREADY DORMANT--and it's small enough, you might actually get away with putting it in the refrigerator until March or so--HOWEVER, the temp inside must remain below 40 F--ideally below 35 F (which is probably one of the colder settings) additionally, the tree must be kept humid. Refrigerator air is bone dry and could dessicate or dry out the tree's tissues over time. You could place the tree in a big gallon sized Ziploc bag, but you'd have to air it out occasionally to prevent mold and mildew.

If the tree is not dormant, putting it in the refrigerator will not make it go dormant and it could also be significantly weakened or killed. I'd also be very careful about where it is placed inside, since having a 5 lb gallon of milk smashed on top of it, or having it greased by a nearby stick of butter won't do it very much good.

Wait to store it until after all the leaves have changed and have fallen off.
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Cellar stairway bulkheads work well too, but you need to watch it for high and low temps. It will be warmer lower closer to the house, and cooler nearer the doors out. If you have the time read the threads on overwintering, you should get some good ideas from those too.
Make sure the tree is watered well before a hard freeze and generally they will be fine. Most Freezing damage happens with trees in soil that is too dry. Once the soil is wet it will freeze and the roots won't get below 32F. During the days when it is warm bring the tree out of the shed to let it thaw so the roots can take up water and water again if necessary before it freezes again.
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