Planting tomatoes two months before the last frost date may seem like a dream. But a device sold variously as Wall O' Water and Wall-O-Water can help mountain gardeners get a head start on planting tomatoes, peppers, basil, and other warmth-loving summer crops. Essentially, the device is a collar composed of vinyl tubes that you fill with 3 gallons of water to form a self-standing, tepee-style cloche 18 inches tall. The tubes absorb solar heat by day then release it at night, keeping the temperature inside the cloche above freezing.

A week before planting, place the empty collar around a 5-gallon bucket on the soil. Then, using a hose, fill each tube three-quarters full with water. Remove the bucket, allowing the collar to close in upon itself. Let the soil inside warm for one week, then plant the seedling in the center of the cloche. Once plants begin to grow through the top, fill the tubes completely with water to expand the top of the cloche. After all danger of frost is past, remove the collar. Gently squeeze the water out of each tube, then dry and store for next year.

Wall O' Water is sold in many garden centers. Mail-order suppliers usually sell it in packages of three for about $9. Wall O' Water can be ordered through Irish Eyes Garden City Seeds in Thorp, Washington (877/733-3001 or www.gardencityseeds.com), and Seeds Trust in Hailey, Idaho (208/788-4363 or www.seedstrust.com).