

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.