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Re: HOW warm for bottom heat?

I would suggest no more than 70 deg, Norm deno has done extensive trials
on this subject and found no benefit to temps above 70. As to freezing
in a househould freezer there is no benifit to the practice in most
cases. There are much better and safer means of dealing with hard seed
coat dormancies, and that is about the only possible benefit of
freezing. Stratify temps. should be just above freezing, for most
species 40F works well. Some ranunculacaea and a few others may benefit
from lower (not les than 28f temps). In general stick to 40 for seeds
that need stratified. At much lower temps. metabolic activity
effectively stops and you are just storing seed not germinating it.
Freezing in home freezers is perfectly safe for storing seed as long as
the moisture content is very low, indeed this is how seed banks store
seed but the temps are much lower ie. as close as possible to absolute
0. To stratify seeds must be fully imbibed (have taken up all the water
that they can) placing dry seeds in cold conditions has no benifit. For
much greater detail see Seed Germination Theory and Practice by Norm
Deno. (a brief version of his work is supposed to be published by Ortho
Books) .

Bob Stewart Arrowhead Alpines (our catalog also has fairly good
germination instructions and they can be reprinted without my permission
I don't have the Alpine-l copyright mentality.)
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