Daniel Gill, Merrill, Thomas A. | 12/23/2005 2:16:29 AM
By Dan Gill
LSU AgCenter Horticulturist
Cool days and chilly nights are just the kind of weather lettuce enjoys. Lettuce is a vegetable that is easy to grow, delicious and so attractive that any gardener – whether you have a vegetable garden, flower garden or even a garden in containers on a balcony – should include it in the garden.
According to references, 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 of lettuce 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 high for lettuce to endure them. Lettuce is a cool-season crop here in Louisiana. Our planting season extends from September through March, with harvest ending in May.
Garden lettuces can be divided into three classes based on habit of growth – leaf or looseleaf types, semi-heading types such as butterhead and romaine (or cos) and heading or crisphead types. Crisphead lettuces, such as the iceberg types available in supermarkets, are more of a challenge to grow here, so I recommend that you stay with the leaf and semi heading cultivars. Other than avoiding the heading types, feel free to try just about any cultivar that strikes your fancy.
Leaf lettuces are the most decorative, least demanding, and 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, only the largest leaves are removed, which allows the plants to continue to grow and produce. A bed of leaf lettuce harvested this way can produce salads for a month or more. With that in mind, it’s a good idea to plant several crops in succession through the growing season for continued harvests.
The butterhead lettuces have soft, tender leaves and relatively loose heads. Their fragile leaves make them difficult to ship and pricey at the supermarket. But these delicious butterheads are quite easy to grow. 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 tiny 8-inch heads to large heads that can reach well over a foot tall. The foliage can be red or green, smooth or ruffled.
Lettuce transplants of various types generally are available in area nurseries and can be planted now through late March. You will find a much larger selection of cultivars available from seeds, which may be obtained locally in seed racks or from 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 accomplished by keeping the plants well watered and fertilized. Water thoroughly during dry weather, and keep the plants mulched to prevent drought stress. Side-dress with granular fertilizer every six weeks or apply a soluble 20-20-20 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 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 dressing is applied and the salad is served. Looseleaf lettuce is best harvested by cropping. Butterhead can be harvested by cropping or cutting the entire plant, and romaine is best if the entire plant is harvested when ready. All lettuce should be harvested by early to mid-May, since high temperatures will cause the lettuce to become increasingly bitter and to bolt (send up a flower stalk).
Its beauty, ease of culture and delicious foliage make lettuce an excellent choice for any gardener. Even you flower gardeners should give it a try – you’ll be glad you did.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.