Lettuce varieties are best planted in succession starting in mid-spring. Lettuces generally do not like heat, and tend to bolt. These lettuces that we offer are bred to be bolt-resistant under heat stress, though extreme heat will bolt just about any lettuce with the exception of Ben Shemen and Jericho, which were bred for heat-tolerance in the Negev desert. Our own Bronze Arrow is pretty darn heat tolerant as well. The others are heirlooms that have taken reasonable heat well, some over centuries of use. Shadecloth will greatly improve heat resistance and leaf quality.
Encourage quick growth for best flavor and tenderness. so assure water and fertility. Lettuce seeds will not sprout once temperatures reach 85 F degrees. In summer heat, sow in the evening, water well, and give some shade.