Re: Cold Frame Gardening
One of the best sources for info on four-season growing is Eliot Coleman (and his wife, Barbara Damrosch). They are in Maine and grow year-round.
Their site is http://fourseasonfarm.com
His book called “The Winter Harvest Handbook,”about growing offseason in unheated or minimally heated moveable plastic greenhouses (not unlike a coldframe!) can be found here:
Here’s a piece from the Maine Organic Growers group about the tunnels he sets up that caught my attention some months back:
A link to his book “Four Season Harvest” is lower down on that page. He is definitely the expert I’d rely on in exploring this topic, hands-down.