Lettuce, a cool-season vegetable crop, is one of the easiest to grow. Lettuce withstands light frost; however, sunlight and high summer tem-peratures usually cause seedstalk formation (bolting) and bitter flavor. Slow-bolting or heat-resistant varieties are available and are rec-ommended for extending the lettuce-growing season. Lettuce planted in very early spring should be given full sun so that the soil will warm enough for rapid growth. For long-season lettuces, plant so that crops such as sweet corn, staked tomatoes, pole beans or deciduous trees will shade the lettuce during the hottest part of the day, when temperatures are over 70°F. Interplanting (i.e., planting be-

tween rows or within the row of later-maturing crops like tomatoes, broccoli, and Brussels sprouts) is a space-saving practice. Many lettuces are attractive in flower borders.

Sow seed in situ in a seedbed, or cell packs for transplanting. Transplant lettuces in moist conditions when they have five or six leaves, with the base of the leaves positioned just above soil level. In hot weather, shade young plants until they are established. In late fall or early winter, protect lettuces with cloches to improve the quality of the crop.

Sowing or planting in early spring in an un-heated greenhouse, beneath cloches or float-ing row cover, or in cold frames, may obtain earlier lettuce crops. Lettuce matures in 40 to 80 days, depending upon the variety.

Culture

Lettuce is, by far, the world’s most popular salad plant and has been cultivated for more than 2000 years. Ancient records note that lettuce was served at the royal table of Persian kings as early as 550 B.C. It was customary for Romans to precede their gargantuan ban-quets with refreshing lettuce salads. Dried lettuce juice was used to aid sleep in Elizabe-than times. And today you rarely see a home garden without some kind of lettuce grown in it.

Lettuce is usually eaten raw in salads. The freshly picked leaves are both delicious and nutritious. The darker-green leaf types contain greater quantities of vitamins. Red-pigmented lettuces contain more vitamin C than their green counterparts. Unfortunately, the vitamin C in lettuce is lost within a few days of storage. By growing your own lettuce, you can harvest lettuce for maximum nutrition. The range of leaf color also gives them decorative value. There are several types of lettuce commonly grown in gardens.

Crisphead, also known as “iceberg”, is the lettuce most widely available as a fresh market type. It has a tightly compacted head with crisp, light green leaves. Many gardeners find this type difficult to grow because it requires a long season and some of the most advertised varieties are not heat-resistant and tend to go to seed as soon as temperatures go up. Select a slow-bolting variety and start seed indoors in late winter or late summer for best results. Transplant in early spring or fall to take advan-tage of cool weather and mulch well to keep soil temperatures from fluctuating and to hold in moisture. Organic mulch is more suitable than black plastic after the soil warms up.

Mulching also keeps soil off the leaves, reduc-ing chances of disease from soil-borne organ-isms.

Butterhead, or Bibb lettuce (developed by Kentuckian, John Bibb), is a loose-heading type with dark green leaves that are some-what thicker than those of iceberg lettuce. But-terheads develop a light yellow, buttery ap-pearance and are very attractive in salads. There are miniature varieties of butterhead, which are very easy to grow, requiring a short growing time. One head of this lettuce is about right for one or two servings, so this is one lettuce to plant in succession, about two weeks apart. It may be started indoors for an even longer season. Bibb lettuce will develop bitterness readily if temperatures get too high.

Romaine, or Cos, is less commonly grown by gardeners, but is a very nutritious lettuce that deserves attention. It, too, is relatively easy to grow, forming upright heads with rather wavy, attractive leaves. Cos lettuce is important in Europe and is popular in Caesar salads in the United States.

Leaf type lettuce, either with green or reddish leaves, is the one most gardeners raise. This type is fast growing, long-lasting lettuce and used for salads and sandwiches. Leaf lettuce basically needs only to be planted, thinned, and harvested. Cultivate carefully as lettuce is shallow-rooted. Use frequent, light waterings to encourage rapid growth, but do not over-water, as this may cause disease of roots or leaves. Overhead watering should always be done in the morning to give plants time to dry off. As mentioned above, mulches are helpful in maintaining soil moisture and keeping leaves off the ground.

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MG 232 March 1, 2003

Master Master Gardeners Gardeners

JournalJournal

Lactuca sativa

Pests As most greens are fast growers, they don’t have many pests. Aphids can be a problem. Aphids are soft-bodied, sucking insects that are sometimes called plant lice. They feed on plant sap and subsequently excrete sugary honeydew that can attract ants as well as sup-port the growth of a saprophytic fungus called sooty mold. There are several species of aphids, all of which belong to the insect family Aphididae, that are capable of attacking any type of vegetation. Control aphids with a hard spray of water as well as applications of hot pepper wax or insecticidal soap. For more information, consult University of Wis-consin Extension publication A2088, Managing Insects in the Home Vegetable Garden.

Slugs are common garden pests that can be quite difficult to control during wet growing seasons. These creatures hide under rocks, boards and garden debris during the day, and feed on plant material at night. They create large ragged holes in leaves and seed-lings and deep gouges in ripening fruit and vegetables. Slimy worm-like trails can sometimes be seen on fruit or foliage. Gardeners can get partial control by removing rocks, boards, debris and unneeded mulches. Space plants to allow air circulation and avoid overhead watering. Reducing hiding places will reduce populations. You can use boards as a trap. Place boards in affected areas. Each day you can lift the boards to remove and destroy the slugs that have crawled underneath. Shallow cans or pie plates filled with stale beer also make good traps. For more information on “Controlling Slugs”, refer to Infosource Number 485.

Irrigation Leafy vegetables, such as lettuce, re-quire frequent watering to help them crop heavily. If rainfall is inadequate, irrigate with 1 to 1½ inches of water per week in a single application. Fre-

quent light sprinklings encourage shal-low roots, making plants more suscep-tible to drought. The most critical wa-tering period is about seven to ten days before maturity.

Fertility Fertilizer recommendations should be based on the results of a soil test. Contact your local Cooperative Extension office for information on soil testing. As a general rule, however, apply and work into the soil

three to four pounds of 10-10-10 fertilizer per 100 square feet of garden area. For transplants, use a starter fertilizer such as 15-30-15, 10-52-17 or similar analysis.

MASTER GARDENERS

Compiled By John T. Kovatch

Harvest have elongated and overlapped to form a fairly tight head about 4 inches wide at the base and 6 to 8 inches tall. Crisphead is matured when leaves overlap to form a head similar to those available in groceries; heads will be compact and firm.

Crisphead lettuce will keep about two weeks in the refrigerator. Leaf, Bibb and Romaine will store as long as four weeks if the leaves are dry when bagged. If lettuce is to be stored, harvest when dry, remove outer leaves, but do not wash; place in a plastic bag, and store in the crisper drawer.

Most types of lettuce may be grown as cut-and-come-again seedling crops, especially loose-leaf types, and some romaine types. Once cut they often resprout to produce a second and third crop. Leaf lettuce can be used as soon as plants are 5 to 6 inches tall. Use first the older, outer leaves, which contain high levels of calcium. You may wish to harvest every other one of the larg-est plants to accomplish thinning. Bibb lettuce is matured when the leaves begin to cup inward to form a loose head. The heads will never become compact. Cos or Romaine is ready to use when the leaves

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Milwaukee County UW-Extension 932 South 60th Street

West Allis, WI 53214-3346 Phone: (414) 290-2400

Fax: (414) 290-2424 http://milwaukee.uwex.edu

Ozaukee County UW-Extension Box 994

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Phone: (262) 284-8288 http://www.co.ozaukee.wi.us

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