Plant lettuce in spring or fall for the best harvest

Lettuce grows fastest in cool weather between 60 and 70 degrees Fahrenheit. In most regions, that means planting in early spring (as soon as soil can be worked) or in late summer for a fall crop. If you live somewhere with mild winters, you can plant lettuce in autumn and harvest through winter. Lettuce planted in summer heat will bolt — flower and turn bitter — before you get a full harvest.

A raised bed warms up faster than ground soil in spring, so you can plant 2 to 3 weeks earlier than you could in a traditional garden. In fall, the raised bed also cools down more slowly, extending your harvest window into November or December depending on where you live.

Key Takeaways

  • Lettuce seeds or seedlings go into the raised bed 4 to 6 inches apart, with rows spaced 6 to 8 inches apart, and soil should be loose, rich in compost, and drain well.
  • Seeds sprout in 7 to 10 days and are ready to thin or harvest as baby greens in 3 to 4 weeks; full-size heads take 6 to 8 weeks from planting.
  • Water the bed lightly every day or every other day so the top inch of soil stays moist but not waterlogged, because lettuce roots are shallow and lettuce bolts under stress.
  • Shade cloth or a row cover protects spring lettuce from unexpected heat and fall lettuce from early frost, buying you extra weeks on either end of the season.
  • Harvest outer leaves as soon as they are large enough to eat, or wait and cut the whole head at the base when it reaches full size.

Prepare the raised bed soil before planting

Fill your raised bed with a mix of 50 percent compost and 50 percent topsoil, or use a bagged potting mix designed for vegetables. Lettuce does not need heavy feeding, but it does need soil that drains quickly and holds moisture evenly — compost does both. If your raised bed is already planted with other crops, work 2 to 3 inches of compost into the top 6 inches of soil before planting lettuce.

Rake the surface smooth and level. Lettuce seeds are tiny and need good contact with soil to sprout. Remove any rocks, sticks, or clumps larger than a marble. If the soil is dry, water it lightly the day before planting so it is moist but not soggy when you plant.

Sow seeds or transplant seedlings

You can start lettuce from seed directly in the raised bed or buy seedlings from a nursery and transplant them. Direct seeding is cheaper and faster — seeds sprout in 7 to 10 days — but requires thinning. Transplanting seedlings skips the thinning step but costs more and takes a few extra weeks.

For direct seeding, scatter seeds thinly along a row or across the bed surface, then cover with a quarter-inch of compost or fine soil. Press gently so seeds stay in place. Space rows 6 to 8 inches apart. Water with a mist so you do not wash seeds away. Keep the soil moist until sprouts appear.

For transplants, dig a hole the size of the seedling's root ball, set the plant in at the same depth it was growing in its pot, and firm soil around it. Space transplants 4 to 6 inches apart in rows 6 to 8 inches apart. Water gently after planting.

Thin seedlings to the right spacing

When direct-seeded lettuce is 2 inches tall, thin it so each plant has room to grow. Pinch off or cut seedlings with scissors rather than pulling them out, which can disturb the roots of plants you want to keep. Aim for 4 to 6 inches between plants in all directions.

The seedlings you remove are edible — they make tender microgreens or baby salad. Do not waste them. Thinning feels wasteful but is necessary; crowded lettuce will not form heads and will bolt early.

Water consistently without overwatering

Lettuce has shallow roots and needs steady moisture. Water lightly every day or every other day so the top inch of soil stays moist. In hot weather, you may need to water twice a day. In cool, cloudy weather, every other day is usually enough.

Water at the base of the plants, not on the leaves, to prevent fungal disease. Raised beds drain faster than ground soil, so check the moisture level by pushing your finger an inch into the soil — if it feels dry, water. If it feels wet, wait another day. Lettuce under water stress will bolt and turn bitter even if temperatures are cool.

Protect lettuce from heat and frost

In spring, use shade cloth or a row cover to shield lettuce from unexpected warm spells. Even a few days above 75 degrees can trigger bolting. Drape shade cloth over hoops or stakes so it does not touch the leaves, and remove it on cool days to let air circulate.

In fall, a row cover protects lettuce from light frost and extends the harvest by 2 to 4 weeks. Leave the cover on until temperatures drop below 28 degrees at night, then remove it during the day if it warms above 50 degrees so the plants do not overheat.

Harvest lettuce at the right stage

Lettuce is ready to eat as soon as leaves are large enough to pick — usually 3 to 4 weeks after planting. You can harvest outer leaves one at a time by pinching them off at the base, leaving the center to keep growing. This method gives you greens for weeks from a single planting.

Alternatively, wait until the head is full-sized (6 to 8 weeks from planting) and cut the whole plant at the base with a knife. Harvest in the morning when leaves are crisp and full of water. Lettuce picked in afternoon heat will wilt faster.

Once temperatures stay above 75 degrees during the day, lettuce will bolt no matter how much you water it. Pull the plants and compost them, then wait until fall to plant again.

Frequently Asked Questions

Can I plant lettuce and other vegetables in the same raised bed?

Yes. Lettuce grows shallow roots and does not compete for space with deeper-rooted crops like tomatoes or peppers. Plant lettuce on the edges or in gaps between larger plants. Lettuce also grows fast enough that you can harvest it and replant the space with something else in the same season.

What should I do if my lettuce is bolting?

Bolting means the plant is flowering and the leaves are turning bitter. Once it starts, you cannot stop it. Harvest what you can and pull the plant. Bolting is usually a sign that temperatures are too warm or the plant is stressed from drought. For your next planting, choose a cooler season or use shade cloth to keep temperatures down.

How much lettuce will one raised bed produce?

A 4-by-8-foot raised bed planted with lettuce on 4-to-6-inch spacing holds about 30 to 40 plants. If you harvest outer leaves, you can pick 2 to 3 pounds of greens per week for 4 to 6 weeks. If you harvest whole heads, you get 15 to 20 pounds total per planting.

Do I need to fertilize lettuce in a raised bed?

If your raised bed is filled with fresh compost, lettuce will not need additional fertilizer. If you are replanting in the same bed, work in 1 to 2 inches of compost before planting. Lettuce does not need heavy nitrogen like tomatoes do, and too much fertilizer can make leaves bitter.

Can I grow lettuce indoors under lights?

Yes, but it is not practical for most home gardeners. Lettuce needs 12 to 14 hours of light per day and stays short enough to fit under standard grow lights. The cost of electricity and equipment usually exceeds what you would spend buying lettuce at a store, unless you are growing it year-round in a very cold climate.