Leaves are turning and the tomatoes, peppers and cucumbers have finished the season, but there's still time to grow and enjoy some of the sweetest, crispiest, most flavorful vegetables of the year.

Leaves are turning and the tomatoes, peppers and cucumbers have finished the season, but there's still time to grow and enjoy some of the sweetest, crispiest, most flavorful vegetables of the year.

Cool-season vegetables do best when the average daytime temperature is 65 to 80 degrees, and nighttime temperatures stay in the 40-degree range. Hot weather causes them to become bitter or go to seed, but many can tolerate cooler temperatures and even a light frost.

Cool-season crops still need at least six hours of full sun a day, so plant in rich, well-drained soil that isn't shaded. Select seeds packaged with detailed "days to maturity" information, and then find the average date of your area's first autumn frost. Count the days to maturity backward from the first frost date to determine when to plant. Work some organic fertilizer or compost into the soil about a week before planting, and add a bit at the base of the plants a few weeks later.

Once up and growing, most vegetables need about an inch of water per week, and they'll benefit more from about two deep applications than more frequent light ones. But germinating and newly sprouted seeds should be lightly and frequently sprinkled until they're well established.

Use dried grass clippings, mulch, newspapers or straw to cover the area around the seeds to help keep the soil moist and reduce weeds. Fall garden greens are more productive when harvested early and often. Use the "cut-and-come-again" method of taking mature outside leaves rather than the whole plant. Even if you cut from the center, if you don't cut too closely to the plant's base, you'll have new greens to harvest in a matter of days.

Extend the growing season by covering the plants on freezing nights. Use light blankets, burlap or floating row covers supported by stakes or wire or hoops to keep them off the plants. Be sure they're pulled off once the sun is up. Giving plants even one more layer of protection is like moving the whole garden one full gardening zone south. For an even longer season, build a simple cold frame from inexpensive, recycled materials like straw bales piled up to form walls covered by an old window.

Here are some favorite cool-season crops. Try them, and see which you enjoy, and which do best in your gardening area.

Cut-and-come-again greens:

--Lettuce. Loose-leaf varieties including "Black-seeded Simpson," "Green Ice" and "Prizehead." Or try erect, cylindrical head varieties like "Medallion," "Rouge d'Hiver" romaine and "Olga."

--Spinach. "Tyee hybrid," "Dark Green Bloomsdale" and "Hybrid 7."

--Swiss chard. Yellow and green varieties are hardier than the pinks and reds.

--Kale. "Blue Knight" and "Early Siberian."

Hardy roots:

--Beets. "Ruby Queen," "Red Ace," "Pacemaker II."' Harvest when beets are 1 to 3 inches across and before the first hard frost.

--Carrots. "Scarlet Nantes," "Little Finger," "Danvers Half Long" and "Spartan Bonus." In colder climates, sow 70 days, and harvest before the first hard frost. In milder climates, store right in the ground and dig up as needed.

--Radishes. "Early Scarlet Globes," "Cherry Belle," "Snowbells" and "White Icicle." Radishes left in the ground too long become pithy. Harvest them when young and sweet, as early as three weeks after planting.

--Turnips. "Purple Top," "White Globe" and "Just Right." They taste best when they're medium-sized, about 3 inches in diameter. Store in the ground, cover with mulch and dig as needed. The tops are also delicious cooked as greens.
    
Joe Lamp'l, host of "Growing a Greener World" on PBS, is a master gardener and author. Visit www.joegardener.com.