the protected cold frame
Jane McGary (Tue, 20 Jan 2009 10:28:32 PST)

Jim McKenney's description of his "protected cold frame" is a little
different from what I do -- he covers it with a tarp outside the
lights (the plastic or glass), but I put sheets of microfoam
insulation directly on the plants before shutting down the lights.
However, both strategies seem to have brought our marginally hardy
bulbs through recent below-average temperatures. My low here was only
14 F (minus 10 C), but the temperature did not rise above the
freezing point for about ten days. I pulled the foam off as soon as
the day temperature began to rise, although this entailed working in
snow over knee height. Only a few plants seem to have lost their
foliage, and I think they may survive, though set back. Narcissus
cantabricus and romieuxii varieties are continuing to flower well
despite having been buried in bud or even opening their flowers, and
deprived of much light for 2 weeks because of the foam and the snow
on the lights. (I think some light gets through the microfoam sheets,
which are white and very thin.)

Jane McGary
Northwestern Oregon, USA