Winter Care Question

narmentr

I am looking for advice for winter care of my trees. This will be my second winter in bonsai. Since it freezes here in the winter I kept my trees in the garage under a flourescent light during the day. The garage was cold enough to give them a winter, but it was very messy when it came to watering and they did not get very good light. I am trying to figure out the best course of action. Would building a makeshift greenhouse with some clear polyurethane work? Any help would be greatly appreciated. I don't want to lose any trees to frost or lack of sunlight.

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JohnQuinn

You need to provide more info...what types of trees, typical minimum temps, etc. Truly dormant deciduous trees will not need light and only rare watering. But, do they really need such winter protection anyway? As far as evergreens, you still need to give more info. Depending on species, they might even be happy under a blanket of snow.
Your zone suggests pretty mild winters...

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narmentr

Most of my trees are junipers, procumbens and shimpaku. I also have a black pine, montezuma cypress, pomegranate, chinese elm and a liquidambar forest. I livein the high desert which gets very hot and very cold. Winters usually have several weeks of below freezing temps (low 30's to mid-teens) at night. It is the desert so snow is rare. I know the evergreens don't mind low temps but will the roots freeze being in shallow pots?

B.adair

Not to Hijack the thread narmentr but wered u get the cypress at? ive been trying to find a place in socal that has good cypress..
Thanks,
-Brad

rockm

"It is the desert so snow is rare. I know the evergreens don't mind low temps but will the roots freeze being in shallow pots?"

Shouldn't make much difference for the species you've mentioned, possibly the Chinese elm, depending on the cultivar. A sheltered spot outside outof the wind, under six or seven inches of mulch will probably get all these throught the winter. Trees can take frozen roots--happens all the time in nature. The vast majority of a tree's roots are in the top six or eight inches of soil--above the frost line.

The trick is to shelter bonsai roots from EXTREME, prolonged freezes below 25 F--With mulch, you trap "warmth" (a relative term) that the ground accumulates during the day. The mulch prevent sudden big drops, or increases --which can also be problematic--in soil temperatures. Those temps tend to stay 5-10 degrees warmer than air temperatures. Dont' worry about teens at night, as under mulch, the inner roots of the tree aren't that cold...

narmentr

The input is greatly appreciated. Would it be a waste of time to make a small "greenhouse" type structure, or should they be ok as long as they are sheltered from the extreme cold and wind?

rockm

"Would it be a waste of time to make a small "greenhouse" type structure, or should they be ok as long as they are sheltered from the extreme cold and wind?"

Not only would it be a waste of time, but it could complicate your storage. Enclosed Greenhouse structures, or those that allow light into a closed environment, trap heat. This is a bad thing for overwintering trees, as dormancy depends on the number of "chilling hours" they require to complete the dormancy process. In other words, they need cold, but just nost drastic cold. Structures aimed at trapping heat can cause premature bud break, and premature growth--you don't want your maple pushing new growth in early February...

That said, I use a clear plastic "greenhouse" covering over my cold pit, but the structure's sides remain open for the vast majority of the winter. It is placed in complete shade all through the winter to prevent heat build up. I close it only to keep out torrential rain and too much snow. It is not to retain heat, as much as it's for keeping out too much moisture.

Mcspeed

The wind protection and mulching for cold should be good, a green house becomes heated by the sun, and you have to start regulating temps, by opening and closing something. Unless you have a need otherwise for it, stick with the minimal approach that rockm suggested. Unless of course you want to add the greenhouse monitoring to your routine. The heating up can be an issue by warming too much, and stimulating the tree to start new budding when you don't want it( ie when the new buds can freeze off in winter).

Bill