A simple cold frame keeps seedlings warm when the garden is frozen. The baby lettuces will love you for it.

As humble as many of these mini-greenhouses may look, cobbled from bits of scrap wood and salvaged windowpanes, cold frames have an amazing ability to create micro-climates. You can buy a ready made one (see "10 Easy Pieces: Cold Frames"), or build your own in an afternoon, following Martha Stewart's meticulous step-by-step instructions. Better make that two afternoons.

Or wing it, with an old piece of glass and some two-by-fours, because as the garden writer Henry Mitchell once put it, "it is more important for the gardener to be enchanted than for critics to be pleased."

Above: A sheltered sunny spot in the garden; image via The Turnip Truck.

Above: Another use for flea market finds or your neighbor's castoffs; image via Green Upgrader.

Above: An elaborate Victorian scheme, in the melon yard of the Heligan estate in Cornwall, England.

Above: Fill hollow eggs with potting soil, as they do at Stony Run Farm, for a clever homemade seed-starting kit. Another environmentally friendly option is to start seeds on a bed of coir fiber pellets, available from Grow Organic ($6.49 for 20 pellets).

Above: Monitor soil for optimal germination temperatures for healthier seedlings; image via Burbs and the Bees. We favor using a simple dial model, like a sturdy Taylor, available for $9.99 from Grow Organic.

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Above: Dutch bulbs, including hyacinths and daffodils, forced in a cold frame; image via Growing with Plants.

Above: Transplants in simple clay pots brighten a windowsill; image via Growing with Plants.

A mix of nursery garden starts and flowers welcomes spring in Montana; image via Knitting Iris.

N.B.: This is an update of a post originally published February 28, 2012.