diana chapman
Fri, 12 Nov 2004 07:32:21 PST
Dear Mary Sue and All:

I haven't yet brought my more difficult Calochortus species to bloom, but I
did conduct a little experiment with C. leichtlinii.  I refrigerated half
the bulbs each winter, but left the rest outside in our mild winters where
we experience very little frost, and few nights even near freezing.  The
refrigerated bulbs were much more vigorous when they came into growth and
bulked up at a much greater rate.  In fact, the unrefrigerated bulbs did not
seem to increase in size hardly at all.

It is likely that Jane gets enough winter chill for her high altitude bulbs,
even though her climate doesn't come close to the Great Basin conditions, or
conditions at 6000'.  I don't think any bulbs (or plants) actually need
freezing temperatures, but may need a certain amount of time at temperatures
between freezing and about 40F - that's why chilling crocus and tulip bulbs
in the refrigerator works.  We had discussed some time back winter chill
needs of other plants, such as fruit trees, since this has been studied
extensively, and I believe one of our more knowledgeable members contributed
information regarding this.  Winter conditions where I live are very mild -
not exactly warm, but probably not cold enough for some of the high altitude
Calochortus species to get the requisite number of hours of winter chill,
although that very likely will vary according to species.


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