How to Grow Sun Tolerant Lettuce

Choose lettuce types known to be most resistant to bolting when faced with high heat and direct sunlight. Crisphead-type cultivars include "Ithaca" and "Great Lakes," while bolt-resistant butterheads include "Summer Bibb" and "White Boston." For red lettuce choices, consider "Red Salad Bowl," "Ruby" or the romaine cultivar known as "Cimmaron."

Work a 1-inch layer of compost into the lettuce bed for extra fertility and texture improvement. Lettuce is a shallow-rooted plant; till to a depth of no more than 4 inches.

Plant seeds with summer sun protection in mind. Dig a shallow trench and broadcast seeds at the bottom of the trench. Scatter a thin layer of soil over the top, and cover the seeded trench with a board.

Remove the board once seedlings appear.

Thin lettuce seedlings to 8 to 16 inches apart (romaines and butterheads need the most room).

Mulch the area with a 2-inch layer of wood chips or compost. A thick layer of mulch will not only cut down on the amount of weeding but will help the lettuce plants take in moisture that the summer sun would otherwise wick away from the soil.

Give each lettuce plant at least 1/2 gallon of water each week, which works out to 1 inch of water, with a hose or drip irrigation system. During rainy periods, hold off on supplemental water.

Feed lettuce plants about three weeks after planting. Mix 2 tablespoons liquid fish emulsion per gallon of water for every 25 square feet of lettuce patch. Water the lettuce bed with the liquid fertilizer.

Check soil moisture frequently, especially during hot weather. Ideally, the lettuce patch soil should be moist at all times. Give plants supplemental water if the soil starts to dry out quickly in the summer sun.

Drape shade cloth over lettuce on summer afternoons when the sun is especially intense. Choose a floating-row type of fabric that allows air to circulate at the sides and ends of the garden bed. Anchor the shade cloth at the corners with rocks or stakes.

Feed lettuce plants for a second time, about six or seven weeks after planting the lettuce. Mix 2 tablespoons liquid fish emulsion per gallon of water for every 25 square feet of your lettuce patch. Water the lettuce bed with the liquid fertilizer.

Pinch off the tops of central stems if the plants seem to be getting longer and taller. This elongation is a sign of bolting, or setting seed. Once lettuce plants bolt, the leaves are too bitter to eat. Keeping the central stems from developing seed heads extends the season under hot, sunny conditions.