What to plant
Growing Lettuce in Raised Beds
Lettuce is one of the easiest raised bed crops: sow it 2 to 4 weeks before the last spring frost, thin heads to 8 to 12 inches, and keep the top few inches of soil moist. Even a 6-inch-deep bed works.
| Fact | Detail |
|---|---|
| Seed depth | 1/8 to 1/4 in; seeds need some light to sprout |
| Leaf lettuce spacing | 4–6 in |
| Romaine and butterhead | 8–10 in |
| Crisphead | 10–12 in |
| Bed depth | 6 in minimum |
| Germination | Best in soil 45–75°F; poor above about 80°F |
| Baby leaves | About 25–30 days from sowing |
| Full heads | About 55–75 days from sowing |
When to plant
Lettuce is a cool-season crop. Seeds sprout in soil as cold as 40°F, and young plants shrug off light frost, so the first sowing can go in a month or a little less before the final spring frost. A raised bed dries out and warms in spring well before the surrounding lawn, often gaining you a week or two.
Plan a second season too. Start sowing again about six to eight weeks before the first fall frost, once nights cool. Fall lettuce is often sweeter, and a frost cloth over hoops can stretch the harvest several weeks past the first freeze. Hot midsummer is the hard part; seed sown in soil above about 80°F often fails to sprout, so start summer batches indoors or in shade.
Spacing and depth
Scatter seed thinly in rows 6 to 12 inches apart, or broadcast it in a block, and cover with just a dusting of fine soil. Thin leaf lettuce to 4 to 6 inches and heading types to 8 to 12; eat the thinnings as microgreens. In a 4-foot-wide bed, rows across the width make succession sowing simple.
Lettuce is a good fit for shallow beds. Six inches of loose mix over loosened native soil works, and it is a natural crop for elevated table beds. Our notes on bed depth by crop show which deeper-rooted crops need more. Lettuce also fills gaps around slow starters; plant it between young peppers and pull it before they need the room.
Soil and feeding
Fast, steady growth gives tender, mild leaves, and that takes nitrogen and organic matter. A compost-rich raised bed soil mix with a pH between 6.0 and 7.0 is ideal. Work an inch of compost into the top few inches before each sowing. About three weeks after the seedlings come up, water in a dilute fish emulsion or a balanced liquid fertilizer, and repeat every two to three weeks for cut-and-come-again plantings.
Watering
Lettuce roots reach only a few inches down, so the top of the bed is where water matters. Keep it evenly moist, which in warm spells may mean a light watering every day or two rather than one deep soak a week. Dry soil makes leaves bitter and pushes plants toward bolting. Water in the morning so leaves dry before evening, and mulch with a thin layer of fine compost or shredded leaves once seedlings are a couple of inches tall. Our watering guide covers drip setups for beds.
Crop specifics: succession sowing, bolting, shade cloth, cut-and-come-again
Succession sowing
One big sowing gives you a flood of lettuce for two weeks and then nothing. Instead, sow a short row or a 1-by-2-foot block every two weeks from early spring until the weather turns hot, then pick up again in late summer.
Bolting
Long days and warm temperatures signal lettuce to flower. The center stretches upward, the sap turns milky and leaves go bitter. Once a plant starts, it will not reverse, so harvest it and resow. Choose varieties labeled slow-bolting or heat tolerant for late spring sowings, and plant romaine and loose leaf rather than crisphead where summers come early.
Shade cloth
When daytime highs reach the 80s, stretch 30 to 50 percent shade cloth over hoops on the bed. It cools the leaves, slows bolting and cuts how often you water. Set the cloth so it covers the south and west sides during the hottest afternoon hours.
Cut-and-come-again
Loose-leaf types regrow after cutting. When plants are about 4 inches tall, shear them an inch above the crown, or pick outer leaves and leave the center. Most plantings give two or three good cuttings before they turn tough.
Harvest
Pick in the early morning, when leaves are cool and crisp. Take outer leaves as soon as they are big enough to eat, or cut whole heads at the base once they feel full and firm. Rinse, spin dry and refrigerate right away; lettuce wilts fast in warm air. A 4x8 bed sown in succession can keep a household in salad through spring and fall. When spring lettuce finishes, our summer planting ideas suggest what can follow it.
Common problems
Ragged holes in leaves
Slugs and snails feed overnight. Check the undersides of boards along the bed edge each morning and hand-pick.
Brown, crispy leaf edges
Tipburn comes from uneven watering in warm weather. Keep moisture steady and add shade during heat.
Seedlings collapsing at the soil line
Damping-off fungus likes cold, wet soil. Sow thinly, avoid overwatering and use fresh mix in seed trays.
Clusters of small insects on new growth
Aphids hide in the center of heads. Knock them off with a strong spray of water and let ladybugs work.