Explore the possibilities different types of lettuce have to offer with this comprehensive review of their cultivation and use.
Lettuce is easy to grow. There are many different types of lettuce — dozens and dozens — to choose from, and, with proper planning, this traditionally cool-weather crop can be cultivated almost year-round in much of the country. When served straight from the garden, lettuce, like freshly picked corn, has a sweet flavor and crispy texture that can’t be matched by store-bought versions.
Considering all this, I’m always astounded at the prices shoppers are willing to pay for the very limited lettuce choices offered by most supermarkets. With a little effort, almost anyone — even city dwellers — can enjoy homegrown salad because this compact vegetable can be raised in pots, window boxes, flower beds, or tiny plots of earth.
The word lettuce comes from the Old French laitues, meaning “milky,” which refers to the white sap that is particularly evident as the plant passes its prime. The generic name for lettuce, Lactuca sativa, reflects this, too (lac being the Latin for “milk”). Lettuce is thought to have originated in the Middle East, and it owes its ease of cultivation to an Asian ancestor common to all Lactucas, the weed known as prickly lettuce (L. Serriola). As early as 550 B.C., this vegetable, then known as kahn, adorned the tables of Persian monarchs, and King Nebuchadnezzar grew it in his famous hanging gardens of Babylon. The Chinese and the Greeks (including Aristotle) lauded its virtues, and the Romans liked it served as the first course of their sumptuous meals. (They considered it both an aphrodisiac and a sedative.) Centuries later, Columbus took lettuce seeds with him to the Bahamas, and the plants were also grown at Henry VIII’s Hampton Court, though his sixth wife, Catherine Parr, had her lettuce shipped in from Holland.
Over the hundreds of years that lettuce has been cultivated, several distinct types have evolved. With the exception of crisp-head (often called iceberg) lettuce, this favorite ingredient of many salads contains high amounts of vitamin A, more vitamin B than most vegetables, and a little vitamin C.
Cabbage like crisp-head lettuce is the kind most often found in supermarkets. Though it’s the least nutritious, the ability of some cultivars to stand up to hot weather and to keep and ship well has led to their being preferred by commercial growers. Great Lakes in particular is tolerant of hot weather (matures in 90 days), and Premier Great Lakes is resistant to both heat and tip burn.
Romaine, or cos, lettuce — whose tall, crunchy, spoon-shaped leaves allow in enough light to boost its nutritional value — was developed in Italy and introduced to France by Rabelais. Heat-tolerant and easy to grow, the very big-leaved types produce crisp, white hearts that can be substituted for celery. ‘Paris White’ (80 days), which has a flavor like Brussels chicory, is a favorite and very reliable cos variety. Other popular romaines are ‘Dark Green Cos,’ ‘Parris Island Cos’ and an early dwarf with a sweet taste called ‘Little Gem.’
‘Butterhead,’ or ‘Boston,’ lettuce has soft, tender, rich green outer leaves and white to yellowish hearts. Aside from being nutritious, it’s considered by many people to be the best lettuce in taste and texture. Small, fast-maturing types (60 to 75 days) — such as ‘Buttercrunch,’ ‘Bibb’ and ‘Tom Thumb’ — need cool, spring weather and excellent soil to produce well, but ‘Deer Tongue’ (also called ‘Matchless’) is more heat-resistant. Other butterhead favorites are ‘Dark Green Boston,’ ‘Fordhook’ (both take 80 days to mature) and ‘Summer Bibb’ (62 days).
Loose-leaf lettuce can tolerate much warmer temperatures than heading lettuce, and because it’s also nutritious and fast-growing, and comes in so many different varieties, it’s ideal for home gardens. Some types form fairly compact heads, but most are characterized by loose, open growth habits and colorful leaves that range from frilly to smooth. For example, ‘Salad Bowl’ (heat resistant, 45 days), ‘Black-Seeded Simpson’ (crispy, delicately flavored, 45 days) and ‘Grand Rapids’ (45 days) all have dense clumps of crinkled, light green leaves, while the heat-resistant ‘Oakleaf’ (40 days) and ‘Ruby’ (45 days) have bronze or reddish foliage. There’s another advantage to loose-leaf types: You can harvest the outer leaves, and the plants will keep producing new leaves to be picked later.
There are also numerous dwarf varieties suitable for containers, small gardens, and one-or two-person households.
‘Stem lettuce’, or ‘celtuce’ (80 days), is cultivated like other types, but while bolting (going to seed) makes other lettuces bitter, it’s encouraged with this variety. Though the leaves of celtuce can be used in salads, it’s grown primarily for its stem; it has a crunchy taste similar to hearts of palm and can act as a celery substitute.
As mentioned before, lettuce prefers cool temperatures and is considered to be a spring crop. However, unless your summers are extremely hot or your winters incredibly cold, there are fairly simple ways to extend the lettuce season.
For very early spring lettuce, sow heading types outdoors in mid-autumn in cold frames or under hot caps. (Try cutting out the bottoms of one-gallon plastic milk jugs, and set these, with the caps removed, over the young plants.) In mild climates, a very heavy mulch might be adequate to protect the plants from the cold.
You can start head or cos lettuce indoors four to six weeks before the last frost date; try three small sowings at weekly intervals, and set out the seedling batches successively as soon as the ground is workable. At that time, sow some seeds of the same varieties directly in the garden. The soil must be at least 35 degrees Fahrenheit for germination, which should occur in six to 12 days.
This is the time, too, to plant quick-growing leaf-lettuce seeds — either repeating the procedure at 10-day to two-week intervals, or sowing all your leaf lettuce at once and harvesting the outside leaves as the plants grow.
As the weather warms up, make new lettuce plantings in shadier locations (shade cloth can work wonders), and utilize some of the newer heat-resistant summer varieties that are less likely to bolt — particularly if given plenty of water.
For an autumn harvest, switch, in midsummer, back to the heading or cos types, making successive sowings. (Again, shade cloth helps seeds germinate and keeps the soil moist.) Harvest those that mature before the first frost, and — in milder climates — protect immature lettuce heads under glass or plastic for winter harvesting. In colder areas, move immature plants to a greenhouse or to sunny windows for winter and early spring eating, or sow fresh seeds in indoor containers.
When garden space is limited, lettuce can be intercropped with slower-growing vegetables, such as beets, carrots, cabbage or, for shade, corn. Or use it as a “catch crop,” planting in areas that are temporarily available before sowing or after harvesting other vegetables.
Wherever lettuce is grown, it needs a humus-rich, moisture-holding, but well-drained, soil abundant in leaf-producing nitrogen. In the fall, many gardeners spade in a pound of fresh manure per square foot, letting it age over winter for spring planting. Some merely mix in aged manure and compost just before sowing their seeds. (Blood meal is another favorite fertilizer.) The pH content should be 6.5 to 7.0, so work in lime if necessary.
Indoors or out, sow the tiny seeds only one quarter-inch deep and as thinly as possible. Leave 18 inches between rows. Since lettuce needs a little light to germinate, some gardeners broadcast the seeds and rake over enough soil to barely cover them.
A small seed packet generally plants a 100-foot row, which will produce approximately 80 heads, or about 50 pounds of leaf lettuce. Germination rate is more than 80 percent, and seeds remain viable for five to six years. Lettuce, however, needs cool temperatures to germinate. Therefore, if the earth is very warm, pre-sprout the seeds for five days in the refrigerator on wet blotting paper, or mix them with a little moist peat moss and perlite.
Transplant seedlings to the outdoors when they are no more than two inches high. Handle them very carefully, since a damaged seedling is vulnerable to the disease gray mold. Do this in late afternoon (and water immediately), or else provide these young, wilt-prone plants with some kind of temporary shading.
In the garden, thin seedlings when they have four leaves. Head or romaine lettuce should stand 12 to 16 inches apart (nine inches for dwarf types). The same applies for leaf lettuce if you intend to pick the outer leaves over a long period, but if you’ll be harvesting whole plants, four-inch spacing is adequate. In fact, many leaf lettuces are planted in thick rows or patches and not thinned at all. Thin butterhead lettuce until the plants are three to five inches apart.
Because lettuce has shallow roots, keep the surface soil moist but not soggy. Lettuce is 90 percent water, however, so try to give the plants three to four gallons of water per square yard weekly in dry weather. To prevent diseases, water in the mornings on sunny days, so that the leaves are dry by evening. In hot weather, the best way to assure surface moisture — and clean leaves — is with a mulch of grass clippings, hay, or straw — especially if applied just after a good rain. Lettuce beds are great places to use soaker hoses or watering wands. Lettuce doesn’t compete well with weeds, but its surface roots are easily damaged by hoeing; again, weed-suffocating mulch is the answer.
There are a number of insects and diseases that can attack lettuce, but if you plant in a rich, well-drained soil and keep your lettuce weed-free, you’ll seldom encounter serious problems in the lettuce patch. Among the most common pests are cutworms, which chew through the stalks of the main plants. To prevent them altogether, put paper, plastic, cardboard or metal collars around the plants. Lettuce-loving slugs, which nibble on leaf ribs during the night, are best caught and disposed of at that time. If you lay out boards, the slugs will hide under them during the day and can be collected, or you can put out saucers of beer to attract and drown them. Limestone or wood ashes sprinkled over the soil around the plants will also discourage slugs. If aphids become a problem, attack them with hose or garlic sprays, diatomaceous earth, wood ashes, or ladybugs.
About the only disease you’re likely to see is rot, which turns a plant black and foul smelling. Soggy soil and crowded plants are usually the culprits. Crop rotation is a preventive measure. Gray mold turns areas on lower leaves grayish green or dark brown and is usually caused by damp, overcast weather. The only solution here is to pull up the infected plants and dispose of them well outside of the garden area.
The quality of mature plants deteriorates quickly if lettuce is not used at its prime, so make extra plantings rather than trying to extend a harvest. To test the firmness of heading types, press down gently on the heart of the lettuce with the back of your hand. Don’t pinch it, as this can bruise the heart. Picking lettuce in the early morning preserves the crispness it acquires overnight. Use a sharp knife to cut the heads just below the lowest leaves, or pull the plants out by the roots. For the best flavor and nutrition, use lettuce immediately. If that’s not possible, wash it thoroughly but briefly in cold water, and drain it well. Refrigerated, most lettuce will keep for up to two weeks.
As mentioned, loose-leaf lettuce can be harvested many times if only the lower leaves are picked, and pinching off the top center of the plant will discourage it from bolting. There will be a subtle elongation of the plant just as it begins to bolt. At that point, it will start to form a bitter white sap. Should any plants start to go to seed, pull up and discard them — unless, of course, you’re a seed-saver. In that case, choose the last plants to bolt, as quickness to bolt is a bad trait. Also remember that any lettuce can cross with other varieties as well as with wild lettuce.
And don’t think of lettuce as just a salad ingredient. It can be lightly steamed, baked, or used in soups. We've provided links to a couple lettuce recipes to get you started.
MOTHER EARTH NEWS’ gardener Susan Sides, tells why lettuce, these days, need never be a humdrum crop:
This past year we grew some 18 varieties of lettuce at the MOTHER EARTH NEWS gardens and found that this vegetable’s astounding array of shapes and colors makes it an excellent edible ornamental. From seed to mature plant in an average of two months, lettuce quickly creates borders and blocks of color that used to be reserved for nonedible edging plants.
‘Pandion’ (a mild, lime green butterhead from Johnny’s Selected Seeds) was so beautiful that none of my lettuce-hungry friends (nor myself) could bear to harvest a head on the first planting. ‘Royal Oakleaf’ from The Cook’s Garden stoically resisted bolting and garnered oohs and ahs from each and every visitor. ‘Little Gem’ (also known as ‘Sugar Cos’) from Bountiful Gardens is a mild-tasting mini-romaine that wowed even those who were turned off by store-bought types.
Mesclun-growing (long-practiced in Europe where salad greens are darker and much more diverse in texture and taste) is an art being popularized in this country through small seed houses with access to excellent European seed. “Cutting mix” is another name for mesclun, which perhaps gives you a clearer idea of the concept. A variety of salad green seeds that may include lettuces, chervil or other herbs, and chicories and arugula or other bitter greens are mixed together and sown en masse. The resulting blend of colors and textures creates a most interesting pattern in the garden, as well as variety in the salad bowl.