Cool days and chilly nights are just the kind of weather lettuce enjoys. Lettuce is a vegetable that is easy to grow, delicious to eat and so attractive to the eye that any gardener – whether you have a vegetable garden, flower garden or even container garden on a balcony – should include it.
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 appear in seed catalogs every year.
Although you may read about cultivating lettuce during the summer in Northern states, Louisiana summer temperatures are way too hot for lettuce to endure. Lettuce is a cool-season crop for us here. Our lettuce planting season extends from September through March with harvest ending in May. January is a great time to plant seeds directly into the garden or in flats or pots to produce transplants.
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 that 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, 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, allowing 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.
The butterhead lettuces have soft, tender leaves and relatively loose heads. Their fragile leaves make them difficult to ship and pricey at the supermarket. As delicious as they are, 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 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, which may be obtained locally in seed racks or from mail order companies and planted this month.
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 them frequently until they germinate. And once they come up, thin the plants to the appropriate spacing – on average 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. 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 can damage the foliage on occasion. If temperatures below the mid-20s 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. Loose-leaf lettuce is best harvested by cropping and butterhead by cropping or cutting the entire plant. Romaine is best if the entire plant is harvested when ready.
All lettuce in Louisiana should be harvested by early to mid-May as high temperatures will cause the lettuce to become increasingly bitter and bolt, sending up a flower stalk.
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.
Dan Gill is a horticulturist with the LSU AgCenter. He can be reached at DGill@agcenter.lsu.edu