BOSTON — There's an art to the timing of vegetable planting, whether in a window box, pots, or a plot in the back forty.
But don't despair if you missed the Northern Hemisphere spring-planting window. You can sow seeds now for produce that can be savored in autumn and even into early winter.
In fact, for American gardeners in the Southeast and Southwest, where summers are hot and winters mild, most crops fare better if started late in the season.
Seed catalogs are increasingly providing seeds that are adapted to the shorter days, cooler temperatures, and higher rainfall of autumn.
Shepherd Ogden, founder of The Cook's Garden, a mail-order seed company based in Londonderry, Vt., explains that late-season is different from early-spring gardening. In springtime, the weather begins cold and often rainy, and gradually moves to the hotter temperatures of summer. In autumn, it's the reverse.
The vegetables best suited to late-season gardening fit into two groups: greens and roots. The first group includes unusual varieties of mild and sharp-tasting greens that are too fragile to be grown commercially, so you won't find many of them in the produce section of your local grocery.
Because greens work well in containers, they can be grown in limited space. These include leaf lettuces, mustard greens, spinach, curly endive (or frise), Swiss chard, corn salad (mche), curly cress, and tat-soi (an Asian green often used in stir-fry). Roots vegetables include carrots, beets, parsnips, radishes, kohlrabi, and turnips.
Plants to avoid, according to Mr. Ogden, are tomatoes, eggplants, and peppers, whose flowers become sterile above 80 degrees F., and will not set fruit.
To make the most of late summer vegetable gardening, Ogden offers these tips:
Use reliable seed. Many gardeners buy all their seeds in spring, and store them in the refrigerator sealed in an airtight jar with a packet of desiccant. If you aren't that organized, start fresh with new seed. Look for varieties labeled "cold hardy," that mature quickly (oak-leaf lettuce, for example, matures in 50 days, compared with iceberg lettuce's 85 days). Sources for seeds include The Cook's Garden (800-457-9703), Shepherd's Garden Seeds (860-482-3638), Johnny's Selected Seeds (207-437-9294), Burpee's (800-888-1447), and Seeds of Change (888-762-7333).
Know the right temperature for germination. Beans love hot weather, but lettuce seeds won't germinate in temperatures above 80 degrees F. Ogden recommends starting lettuce indoors, and then planting it outdoors in an area protected from the sun.
For an attractive container garden, take an oak half-barrel and sow morning-glory or pole-bean seeds five or six inches apart. Before the vines emerge, build a support by tying bamboo poles together teepee-style. Lettuce seedlings can be planted in the shade afforded by the vines.
Eat the thinnings. Loose-leaf lettuces are an excellent choice for people who don't believe in delayed gratification. When you thin out the tiny seedlings to create space for the others, the sacrificial greens can go right into a salad or be used to garnish soup. Most greens are better eaten as young things.
To help determine the timing of a late-season crop, Ogden says, "you need to answer the question: Are conditions getting better or worse in your part of the country?"
In the desert Southwest, for example, autumn brings a respite from the dry, dusty heat that can prevent seeds from germinating.
For specific information on planting times in your area, Ogden suggests looking in the phone book or on the Web for the nearest university or county cooperative-extension service.