Lettuce is grown for its foliage, typically as a salad crop. While it naturally thrives in the hot sun, lettuce tastes better when grown as a cool crop. It’s also a low-feeding, fast-growing crop, making it a prime candidate for companion planting and succession planting.
Find a spot in your garden with primarily eastern or southeastern sun as lettuce tends to bolt in the hot afternoon sunlight. Prepare the soil by adding at least ½” of compost or some type of loose organic matter, and then thoroughly rake it into the top 3-4” of soil. Slightly mound the soil as lettuce prefers damp but well-draining soil.
Plant the lettuce as soon as the soil is workable, as early as late March, as it can withstand a light frost. It will germinate in soil temperatures as low as 4oC, but it prefers and will germinate faster in temperatures of at least 10oC. It can then be succession planted all year. Find a cool, shady place when planting lettuce during the summer.
Lettuce can be either sown directly into the garden or started indoors and transplanted in seedling form after hardening them off. Usually, a combination of both is ideal as you want to spread out the planting to spread out the harvest.
Plant lettuce (or thin seeds to) 3-4” apart for cut-and-come-again lettuce and 8-12” apart for head lettuce. Lettuce seeds should be pressed into the soil rather than planted in small holes in the soil. Water immediately after planting and keep the soil damp for the first week.
Keep lettuce out of the hot, late-day sun by using shade cloth or placing taller plants on the west side of your lettuce as it matures. Fertilize occasionally with nitrogen-heavy supplements and add calcium supplements (such as lime or gypsum) if you prefer crisp lettuce. Avoid using any type of manure on lettuce to minimize the risk of e-Coli contamination.
Watch closely for drooping leaves, which indicate overheating or underwatering. If you see the leaves drooping, mist them with water to help cool the plant. Finally, keep the area well-weeded to ensure that no weeds are accidentally harvested with the lettuce itself.
Pests and Diseases
Lettuce is susceptible to a few pests and critters, including aphids, rabbits, slugs, and snails. Consider growing beneath row cover to prevent them from nibbling on your lettuce.
Lettuce is also susceptible to a few diseases, including gray mold and powdery mildew. To avoid these diseases, ensure that the plants do not get overwatered.
Lettuce may be harvested in one of two ways. For loose-leaf lettuce, harvest using the cut-and-come-again method. Whenever the leaves are at least 6” high, cut the leaves down to 2.5” high and place the cuttings into a bag to maintain freshness. The remaining 2.5” of leaves are sufficient to photosynthesize, and the plant will regrow and enable future harvests from the same plant.
For head lettuce, wait until the lettuce heads are full-sized and then cut them at the base of the stem. At this stage, you can either plant new lettuce seeds or seedlings or plant another vegetable in the space where you harvested the lettuce head.
© Homestead Toronto / Derek Barber