Richard Bogren, Gill, Daniel J.
For Release On Or After 01/08/10
By Dan Gill
Early references say lettuces were cultivated 3,000 years ago by the Babylonians and possibly earlier by the Chinese. Lettuce seeds were sealed in Egyptian tombs, and lettuces were served to Roman emperors. On European tables during the Middle Ages, lettuce was mostly eaten hot. By 1865 seed companies offered 113 kinds to America’s gardeners. Today, lettuce is so popular that new and interesting varieties appear in seed catalogs every year.
Although you may read about cultivating lettuce during the summer in northern states, our summer temperatures are way too hot for lettuce to endure them. Lettuce is a cool-season crop for us in Louisiana. Our lettuce-planting season extends from September through March, and harvest ends in May.
Garden lettuces can be divided into three classes based on habit of growth – leaf or loose-leaf types, semi-heading types (such as butterhead and romaine or cos) and heading or crisp-head types.
Crisp-head lettuces, such as the iceberg types available in supermarkets, are more of a challenge to grow here, so I recommend you stay with the leaf and semi-heading varieties. Other than generally avoiding the heading types, feel free to try just about any variety that strikes your fancy.
Leaf lettuces are the most decorative and least-demanding. They also are among the most heat-tolerant lettuces we can grow. This type of lettuce grows in a loose rosette of foliage, and the leaves can be smooth or crinkled, pointed, lobed, curled or ruffled. Foliage color runs from deep ruby red to dark green to pale greenish yellow, with just about every combination in between.
Leaf lettuces are fast-maturing and can be ready to begin harvesting just 40 days after planting. Harvesting is best done by cropping the plants regularly. When cropping, remove only the largest leaves and allow the plants to continue to grow and produce. A bed of leaf lettuce harvested this way can produce salads for a month or more. It’s a good idea to plant several crops in succession through the growing season for continued harvests.
Butterhead lettuces have soft, tender leaves and relatively loose heads. Their fragile leaves make them difficult to ship and pricy at the supermarket, but they’re easy to grow. And they’re delicious. They can be harvested by cropping, or an entire plant may be harvested as the center leaves grow over and form a loose head. Varieties to choose include Bibb and Buttercrunch.
Romaine, or cos, lettuces are tall, upright and thick-leaved. Their thick midribs and sweet, juicy texture have made them especially prized for salads. They range in size from 8-inch heads to larger heads that can reach well over a foot tall. The foliage can be red or green, smooth or ruffled.
Lettuce transplants of various types are generally available in area nurseries and can be planted now through late March. You will find a much larger selection of varieties available from seeds that are sold locally in seed racks and by mail-order companies.
Plant lettuce seeds into well prepared beds that have been amended by digging in a 2-inch layer of organic matter, such as compost or rotted manure, and an all-purpose granular fertilizer. Lettuce seeds need light to germinate, so they are simply pressed or lightly raked into the soil surface. Water frequently until they germinate, and once they come up, thin the plants to the appropriate spacing. The average spacing is about 10 inches between plants.
For best quality, lettuce must be encouraged to grow rapidly. This is done by keeping the plants well watered and fertilized. Water them thoroughly during dry weather and keep the plants mulched to prevent drought stress. Sidedress with granular fertilizer every six weeks or apply a soluble 20-20-20 fertilizer every two weeks during the growing season. Stress from drought, heat or low fertility encourages the lettuce to become bitter.
Even though lettuce is best grown here in the winter, hard freezes occasionally can damage the foliage. If temperatures in the mid-20s or lower are predicted, throw a layer of pine straw or sheets of fabric over the plants to prevent frost burn.
Lettuce is wonderful harvested moments before the salad is dressed and served. In Louisiana, all lettuce should be harvested by early to mid-May because high temperatures will cause the lettuce to become increasingly bitter and bolt, sending up flower stalks.
Its beauty, ease of culture and delicious foliage make lettuce an excellent choice for any gardener. Even flower gardeners should give it a try. You’ll be glad you did.