Lettuce is a cool-season vegetable and develops best quality when grown under cool, moist conditions. Lettuce seedlings will tolerate a light frost. Temperatures between 45 F and 65 F are ideal.
Lettuce grows in a wide range of soils. Loose, fertile, sandy loam soils, well-supplied with organic matter are best. The soil should be well-drained, moist, but not soggy. Like most other garden vegetables, lettuce prefers a slightly acidic pH of 6.0 to 6.5
Lettuce can be planted in the spring when the soil is dry enough to rake the surface. Lettuce does not withstand hot summer days well and spring planting should be completed at least a month before the really hot days of early summer begin.
Successive plantings at 10 to 14 day intervals provide a continuous supply of lettuce
butter buttercrunch or bib lettuce
Fall plantings started in late summer mature during cool fall weather. Watering is essential for seed germination and establishment of seedlings. Some shade may also benefit summer sowings. Heat-tolerant varieties (mainly loose-leaf types) may be grown in the shade of taller crops through most of the summer
Plant lettuce seeds shallow. Cover your seeds with 3/8 – 1/2 inch of soil.
Plant seeds 1/4 to 1/2 inch deep (10 seeds per foot) in single, double or triple rows 12 to 18 inches apart. Thin seedlings to 4 inches apart for leaf lettuce and 6 to 8 inches apart for Cos or Butterhead. The seedlings removed may be transplanted or eaten.
Transplant lettuce to the garden when there are at least 4 true leaves on the starts. Make sure the soil is moist before planting. Start indoors
Keep lettuce well moist. Water your lettuce plants everyday, if it is extremely hot and dry.
Make sure soil contains a good supply of nitrogen for good leaf production.
An organic mulch will help conserve moisture, suppress weeds, and keep soil temperatures cool. If weeds do become a problem, either pull by hand or cultivate very shallowly to avoid damage to lettuce roots. Planning your garden so that lettuce will be in the shade of taller plants, such as tomatoes or sweet corn, in the heat of the summer, may reduce bolting.
Harvest Lettuce when full size but young and tender. Over-mature lettuce is bitter and woody. Leaf lettuce is harvested by removing individual outer leaves so that the center leaves can continue to grow.
Pick Lettuce before it gets bitter. If flowering stalks appears, the plant is past its prime
Types of Lettuce
Crisphead lettuce is probably the most familiar of the four. It is characterized by a tight, firm head of crisp, light-green leaves. In general, crisphead lettuce is intolerant of hot weather, readily bolting or sending up a flower stalk under hot summer conditions. For this reason, plus the long growing period required, it is the most difficult of the lettuces to grow in the home garden.
Butterhead types have smaller, softer heads of loosely folded leaves. The outer leaves may be green or brownish with cream or butter colored inner leaves. There are several cultivars available that will do well in Ohio gardens.
Leaf lettuce has an open growth and does not form a head. Leaf form and color varies considerably. Some cultivars are frilled and crinkled and others deeply lobed. Color ranges from light green to red and bronze. Leaf lettuce matures quickly and is the easiest to grow.
Romaine or cos lettuces form upright, cylindrical heads of tightly folded leaves. The plants may reach up to 10 inches in height. The outer leaves are medium green with greenish white inner leaves. This is the sweeter of the four types.
To store lettuce, wash, drip dry and place in a plastic bag in the refrigerator. Lettuce keeps best at 32°F and high (96%) humidity.