The Vegetable Garden

    Lettuce - When To Plant

      When To Plant

      Leaf, Cos and Butterhead lettuce can be planted anytime in the spring when the soil is dry enough to rake the surface. Two or more successive plantings at 10 to 14 day intervals provide a continuous supply of lettuce. 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. 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 if extra care is taken about irrigation and soil selection.

      Head lettuce must be transplanted in most locations and requires more care than other types of lettuce. Start transplants for a spring crop indoors or in a cold frame and set them in the garden as early in the spring as the weather settles. Harden transplants outdoors so that they become acclimated to the conditions under which they will be grown, but do not allow growth to stop entirely. Cos, butterhead and leaf varieties also can be transplanted for earlier harvest. In the heat of summer, lettuce seedlings started in a protected location in the shade can be transplanted later into moderate sites for some limited success.

      Spacing & Depth

      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 Crisphead seedlings 10 to 12 inches apart in the row.

      Care

      Because lettuce has shallow roots, it should be hoed or cultivated carefully. Frequent light watering causes the leaves to develop rapidly, resulting in high-quality lettuce. Over watering, especially in heavy soils, can lead to disease, soft growth and scalding or burning of the leaf margins. Organic mulches can help moderate soil temperature and the micro-environment to produce quality lettuce in less than ideal weather conditions.

      Harvesting

      Leaf lettuce may be cut whenever it is large enough to use. Cutting every other plant at ground level gives the remaining plants more space for growth. Leaf lettuce reaches maximum size (6 to 12 ounces) in 50 to 60 days. Butterhead varieties form small, loose heads that weigh 4 to 8 ounces at harvest (60 to 70 days). The innermost leaves, that tend to blanch themselves, are a delicacy. Cos varieties have an upright growth habit and form a long, medium-dense head.

      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.

      Common Problems

      Aphids — Watch for buildup of colonies of aphids on the undersides of the leaves.

      Tipburnis a physiological condition that causes lettuce to "die back" at the edges of the leaves. It results from a change in the moisture relationship between the soil and the plant. Clip off any brown leaf tissue and use the remainder of the leaf. Frequent light watering helps to prevent tipburn. Some varieties are resistant to this condition.

      Foliage rots can be a problem, especially in hot or wet seasons. Providing good soil and air drainage for the lettuce bed can help to minimize damage in most years.