This is the weekend to start seedlings for broccoli, lettuce, cabbage, Brussels sprouts, cauliflower and potatoes (perhaps those nice new Explorers). If you want to be ambitious, try some onions and leeks, too. Other cool- weather crops, such as spinach, peas, carrots and other root vegetables, can be sown directly into the ground as soon as the soil can be worked.

You don't have to start seedlings this early; many gardeners don't even begin to think about them until the end of February. But if you start now, they'll be ready by the end of March, which will give you the jump on spring.

There's a problem, however: How do you coax little seeds into sprouting when you're trying to be energy-efficient? After all, 70 degrees is the magic temperature to start off the seeds. But how can you warm your soil to 70 degrees when your house is never warmer than 65? Once the seedlings have sprouted, they require an air temperature of about 65 degrees to thrive. They also need lots of light and a good humidity level -- about 50 percent or better.

A warm bathroom with a few grow lights is one way to do it. Another is to buy a miniature plastic greenhouse that will provide high temperatures and humidity in a limited space with little energy consumption. That's the method I chose. I found a Jasco mini-greenhouse on sale at a hardware store for $17. (The regular price is about $25, so I bought two.)

They fit nicely in the two southwest windows in my kitchen. They each hold 24 peat pots, which I filled with milled sphagnum, an excellent, sterile growing medium. The peat pots cost $5 for 50, and the milled sphagnum came to $3 for eight ounces -- enough to fill all the pots with some left over. I planted 12 each of broccoli, cabbage, Bibb lettuce and Explorer potatoes. An hour after I'd put the dampened sphagnum and peat pots under the transparent greenhouse hood, the inside of the plastic was filled with condensation. The greenhouses have small vents at the top, which I opened and left open.

It took only three to five days for the seedlings to sprout. I'd planted two seeds in each peat pot, but oddly enough, most pots bore only one sprout. They're arching toward the window, a problem that will easily be rectified by grow lights hanging over the greenhouse. Because of the condensation inside the little house, it's a good idea to remove the top for most of the day, letting the seedlings breathe and helping them harden off at an early stage.

Peat pots considerably reduce transplanting trauma, since you plant the entire pot in the garden or cold frame. When you use plastic or Styrofoam pots -- admittedly less expensive since they're re-usable -- you have to remove the seedling and risk causing some root damage.

The cost of greenhouses may seem high at first but they should last several years and can be used year-round for different projects. When these seedlings are ready for the cold frame, I'll start such warm-weather plants as squash and tomatoes; next fall, I'll use the greenhouse again for starting indoor herb plants for winter. Besides, there's a lot of satisfaction in seeing the little green things pop up -- a harbinger of spring. ALL RIGHT, ARUGULA: Okay, okay. I stand corrected. Stop the mail and the calls. Park's does carry arugula (or rocket), contrary to what I said in the column last month. Notes came from Tom DeBaggio of Earthworks Herb Garden Nursery, 923 North Ivy Street in Arlington, and from a couple of readers who noted that Earthworks carries arugula plants later in the season. DeBaggio said that he found seeds available through Harris and Herbst Bros., too. Look under rocket, roquette, rugula, rucola and arugula in any catalogue to locate the seeds. He also had a few more words of advice on the growth and culture of this fine, peppery salad green: "Best sown in summer, direct-seeded; transplanted from indoor-germinated seed in spring. Runs to seed as soon as weather warms. One strategy is to plant in early spring, permit limited self-seeding for a fall crop. Two tips for lengthening harvest in warm weather: Plant in shaded spot to moderate heat; when seed stalks begin to appear, cut entire plant back to produce more leaves (and seed stalks). This process must be continued through the summer. As with most strongly flavored plants, rucola should be grown fast and lush with copious water and plenty of fertilizer. Harvest by cutting the outside leaves." A final note from DeBaggio: He'll send rucola seeds free to anyone who'll send him a stamped, self-addressed envelope. The offer is good as long as supplies last. The nursery does not open, however, until March 25.