Lettuce, one example of a weed that made it big, grows in well-drained, rich soil, especially during the coming cooler months. Varieties grown today bear little resemblance to their ancestral strain. Seed scientists believe current types evolved from prickly lettuce, an Asiatic weed.
Plant historians, delving into an ancient past, find lettuce was first cultivated in Persia some 500 years before the Christian era. Seeds later found their way to Europe in the 12th century and eventually to the North American continent, possibly carried there by settlers to the New World. Lettuce seeds could have come over on the Mayflower in preparation for garden planting.
Lettuce grown in colonial gardens may have been the loose-leaf type. The familiar, tightly folded head, popular today is a fairly recent innovation.
The headed variety gained national importance with the development of refrigerated railroad cars, enabling California growers to serve markets extensively.
California, even today, produces much of the head lettuce eaten throughout the United States, although some is grown in Arizona and Texas.
Lettuce contains large amounts of vitamin A. It also has a low calorie count, making it valuable to weight watchers.
The hardy annual can be grown in most home gardens, but present-day lettuce, like its ancestors, requires cooler weather when maturing.
In Florida, sow seeds sometime in November or December to ensure harvest during cooler months.
Will head lettuce grow and mature in Florida gardens? The answer is yes _ with reservations. A growing period requires careful planning to ensure maturity during cool weather months ahead. Most crisp-head varieties, including Great Lakes and Iceberg, require about 90 days or three months to mature and form a head.
Seeds planted as late as some time in December should have ample time for cool weather growth. Heads maturing during warmer weather sometimes become strong to the user's taste.
Home gardeners also have other choices. Loose-head lettuce, including Black Seeded Simpson, Oak Leaf and Salad Bowl, matures in approximately 45 days and can be planted at three-week intervals to ensure a continuous supply.
Bibb types, especially Buttercrunch, produce tightly formed minor heads with crisp, tender leaves.
Then, too, there is Cos (sometimes called Romaine) considered by some gardeners to be one of the most nutritious lettuce types: crisp, sweet and flavorful. It requires 80 days to mature and should be planted with cool months ahead in mind.
Almost any well-drained soil, not too acid, is well suited for growing lettuce. It has few insect enemies or growing problems other than lower leaf rot caused by contact with the soil. Rapid growth requires nutrient-rich soil and irrigation to substitute for possible lack of rainfall.
Sow seeds in rows about 15 inches apart and thin plants to stand from eight to 12 inches apart, thus avoiding overcrowding, a condition that sometimes causes lettuce to bolt (grow tall), producing nothing more than seed.
Leo Van Meer's book, Natural Gardening, is available from Van Meer Publishing, P.O. Drawer 1289, Clearwater 34617 ($10.95 post-paid, plus 77 cents sales tax). Address questions to Garden Naturally, St. Petersburg Times, P.O. Box 1121, St. Petersburg 33731.