Dav4

Thats exactly why I mulch...it decreases the temp swings in the soil. It protects from extreme winter cold, and as I hinted at earlier, I would be very reluctant to let my trident sit in 10F temps without the mulch. It also protects from the soil temps rising precipitously on those late winter days where the sun is intense and air temps in the garage may temporarily rise into the 60's for several days running. If I can keep them dormant into late March, I can move them outside, again mulching them in, and let them wake up as the weather warms up. Most of my trees are big ones, and I like to move them as infrequently as possible

Dave

Kansai

Actually, budding has more to do with chilling requirements than with soil temps. The longer during dormancy that a tree spends in the chilling zone--between 32 and 45 degrees--the less warmth a tree needs before it breaks bud. By protecting trees in garages and such, which of course must be done because they're in containers, you increase the chances that they will max out their chilling requirement and thus break bud early.

You can arrest the budding process by putting the trees outside in a protected area. As long as a bud has not broken it is impervious to frost. It's the roots you need to worry about.

DR

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Bonsai is easy! All you have to do is stare at a little tree until drops of blood form on your forehead.--paraphrased from Gene Fowler

Phil

Would not " chilling requirements" and "soil temps" in a container plant be one and the same thing? If the tree is cold so then would be the soil. Cold temperature "chilling" equals cold "soil". I don't quite get your meaning? Granted, soil will hold more warmth than the ambient air temperature surrounding a tree but cold is ah......COLD! Mind you, I'm talking about a potted tree here as opposed to one in the ground.

~Phil

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Kansai

Chilling requirements have nothing to do with soil temps. A chilling requirement is the amount of time deciduous woody plants need to spend during dormancy at air temperatures between 32 and 45 degrees in order to resume normal growth in the spring. This chilling serves to bleak down growth inhibitors in buds that were set the previous season.

The soil temps don't matter to bud break. If we have a warm day in January that hits 40 degrees, the trees are accumulating chilling hours even if the soil is still frozen 18 inches deep. Or the soil temp can be 40 degrees, but if the air temp dips below 32, the trees quit accumulating chilling hours.

Chilling requirements can range between a few dozen hours and thousands of hours. A tree that doesn't meet its requirement will break bud erratically and incompletely. A tree that exceeds its requirement will likely break bud prematurely and risk frost damage. This is because the more chilling a tree receives, the less warmth it needs to break bud. Under the right circumstances, a tree that has exceeded its chilling requirement could very well break bud before the soil became warm enough to sustain root activity. Likewise, a container tree kept in an artificial environment that increases exposure to chilling will probably break bud sooner than one would like.


DR

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Bonsai is easy! All you have to do is stare at a little tree until drops of blood form on your forehead.--paraphrased from Gene Fowler

Dav4

Boy, I'm going to have to think about this one for a bit. I thought I understood chilling requiremnts...my understanding was that it is a genetically based means of keeping a plant dormant until the likelyhood of frost damage was minimal. I was also under the impression that the slow increase in soil temps was what initiated the break in dormancy once the number of chilling hours had been reached. This would be the safest way for the plant, for sure. By the time the plant's chilling requirements had been met and the soil temps had reached 40F or so, it would be safe for the plant to initiate its spring growth. I would think this is true for both potted trees and trees in the landscape. Here in zone 6, we will routinely warm up into the 50's and 60's for several days in a row throughout the winter. Sometimes, we'll have a week of temps 15-20 degrees above normal. However, my potted trees don't wake up until March or April at the earliest, and the landscape trees don't start pushing leaves until May, generally (I will admit that some buds on some trees will fatten a bit in March if subjected to such warm temps). Certainly, by February, they all would have met the chilling requirements to start growing. So why don't they? I've always assumed it was frozen bonsai soil or the frozen ground. Makes sence to me, anyway. Anyhow, I'm not at home right now, so it will be difficult to look more thoroughly into this right now. Thanks,

Dave

Kansai

As luck would have it, deciduous trees also have a heat-sum requirement that they must satisfy in spring before they will burst bud. This means temperatures must be above certain thresholds for a certain amount of time before buds will burst. The chilling hours are cumulative throughout the entire dormancy. The heat sum, however, will reset to zero if temperatures fall below a certain level--around 35-40 degrees I think--and the tree will have to start from scratch. This means that it has to get warm, and stay warm for a fairly extended period of time before a tree will break bud.

I think soil temperatures and root activity probably would have an impact on bud break, especially its vigor, but I don't see much agreement on exactly what that impact is. I think it is generally excepted that trees have chilling requirements, and that the more chilling a tree receives, the lower the heat-sum thresholds go. And remember that temperatures below 32 degrees do not count toward the chilling requirement.

Several years ago I acquired a property that was overgrown with juvenile mulberries. I went out on a late winter day while they were still dormant, cut them all down and piled then up at the back of the property. Several weeks later I went to haul them off, and I found that my pile of mulberry branches had broken bud and greened up. I could tell they weren't going to get very far but green, juvenile leaves covered the branches.

They could do this because a bud that is formed in the autumn has everything it needs to break in the spring right there in or at the bud itself, plus a growth inhibitor that prevents it from breaking right then on a warm, sunny fall day. Chilling breaks down that growth inhibitor so that on a warm, sunny spring day that bud can burst.

If you want to try it yourself, go out right now and find a crabapple, a cherry, a forsythia or some flowering tree or shrub that's still dormant, cut off some terminal stems, take them inside, put them in a vase with a little water and set them in a warm location. In a few days you should see buds swelling and in a couple or three weeks you should get bud break. It can make a nice pre-spring display.

DR

__________________
Bonsai is easy! All you have to do is stare at a little tree until drops of blood form on your forehead.--paraphrased from Gene Fowler

JTGJr25

Wow, it seems there are many factors that go into the seasonal changes of a tree, or so it seems. Ok well I have another question to add, just after re-potting I plan on wiring the trunks to give them more shape, can I do this in spring? I am afraid that the rapid Spring growth will cause the wire to dig in rapidly. If I do do this in Spring, I will watch it closely and remove it rather quickly. Will this seemingly short amount of time be long enough for the wires to do their thing or should I just wait till summer?

Tom

Dav4

I was actually considering this very thing right after I posted yesterday. I wasn't sure if flower buds opened to a different stimulus as opposed to leaf buds, so I didn't add it to the discussion.

Dave

Tom, you want to wire when the tree is leafless...its easier to apply the wire and you can actually see what you're doing. I would apply the wire just before you re-pot. And yes, you will have to watch the wire closely to prevent damage...trident branches can fatten up very quickly.

JTGJr25

Since I should have to re-pot soon, I decided to wire now. I also thought I should post up a couple pics so you guys can see what I've been talking about. I plan on moving them closer together and changing the angle as well.



Tom

Prowler

No need for that, simply use a far heavier guage of Alum. wire.
This is easier to use than thin wire, it should last a whole season without cutting into the bark, does the same job.
Unless you are going to show your tree why worry.
You can practice on any natural trees in your garden to improve your skills.
You can get marks on your tree by improper wiring, not what you need.
We should all try to improve our skills but not on your favourite Bonsai. Cheers.

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