I agree, in my opinion winter growing bulbs from Mediterranean or continental climates root when Summer heat is mitigated by cooler nights, (and moisture - often in the form of heavy dew). When temperatures drop below 4 degrees Celsius they actually slow down root and top growth,( thus, I believe, allowing flower buds more time to develop inside bulbs). As I have said before, I am under the impression that refrigerators are over used for domestic horticulture in some parts of the world. Frost has arrived here, any winter growing bulbs I now plant will be kept on my coolest frost free window sill where they can root and pretend it is still 'Fall'. They will be put outside, in appropriate frames, in early spring, when well rooted. Peter (UK) On Sun, Dec 2, 2012 at 12:31 AM, Nathan Lange <plantsman@comcast.net> wrote: > > While there are certainly different optimal rooting temperatures for > different species of bulbs/corms, I can't think of a species offhand > that requires a temperature treatment as cold as a refrigerator for > good rooting or rooting initiation. >