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