How to Grow Lettuce: Sow, Space and Harvest Right

Lettuce is the crop most gardeners get wrong by sowing once, in spring, and stopping. A single row planted in April gives a few weeks of salad and then, right on cue for summer, bolts into a bitter flower stalk. Growing lettuce well is less about any one skill and more about a rhythm: sow small batches often, thin properly, and read the calendar rather than fight it. Get that rhythm right and one bed can carry salad from April to the first hard frost.

This guide covers picking a lettuce type that matches what you actually want to eat, plus sowing depth and spacing. It also covers the thinning step most gardeners skip, and the watering and cutting habits that keep a bed productive instead of bolting early.

What You'll Need

• Lettuce seed, at least one hearting type and one loose-leaf type (see Step 1)
• A bed or container in full sun, with moisture-retentive, compost-enriched soil
• A dibber or cane for marking rows
• Fleece or cloches if sowing early or late in the season
• Watering can or drip line for consistent morning watering

Step-by-Step Guide

Step 1: Choose the Right Type for the Season

Lettuce isn't one crop. It's four, and each behaves differently under heat and cold. Picking the wrong type for the month you're sowing is the single biggest reason gardeners think lettuce is fussy.

A practical rule: sow a loose-leaf variety for the fastest returns, and a crisphead or cos for the sowing that has to survive early summer heat without bolting. Butterhead fills the gap between.

Step 2: Sow at the Right Time, in Small Batches

Outdoor sowing runs from late March to late July for summer and autumn harvests, per the RHS lettuce growing guide. For an early winter crop, sow outdoors in early August and cover with cloches from late September. For a spring harvest, sow a winter-hardy variety in September or October under cover.

Sow seed thinly, about 1 cm deep, in rows 30 cm apart. Don't sow the whole packet at once. A full row sown in one go matures in one go, which means a week of glut followed by nothing. Instead, sow a short row every couple of weeks.

The RHS's own guidance on successional sowing is to let the plants set the pace rather than the calendar. Make the next sowing once the previous one has about four true leaves. In practice that lands close to every three weeks in cool spring weather, and closer to weekly once summer speeds growth along.

In hot spells, lettuce seed can be reluctant to germinate at all. Sow in the evening, water with cold water, and give the row some shade until seedlings are through.

Step 3: Thin to the Right Spacing

This is the step most beginners skip, and it's the one that decides whether you get proper heads or a mat of stunted plants competing for light and water.

Thin seedlings as soon as the first true leaves appear, and keep thinning until plants reach their final spacing:

• Hearting types (butterhead, cos, crisphead): 30 cm apart
• Loose-leaf types: 15 cm apart
• Containers: minimum 30 cm width, enough for one hearting plant, or several loose-leaf plants sown closer together

Don't throw the thinnings away: young lettuce seedlings are edible and worth washing into a salad.

Step 4: Water Early, Water Steadily

Lettuce is mostly water, and it shows the moment that water becomes inconsistent: leaves turn bitter, plants bolt early, or hearts stay loose and thin. Water when the soil is dry, and do it in the early morning rather than the evening. Morning watering gives leaves time to dry before nightfall, which matters because damp evening soil is exactly what slugs and snails go looking for, and they are lettuce's most persistent pest.

Keep the soil moisture-retentive rather than waterlogged. A light mulch around (not touching) the base of the plants evens out the swings between watering days. That matters more for lettuce than almost any other vegetable. Its root system is shallow, with very little reserve to draw on.

Step 5: Harvest at the Right Moment, the Right Way

How you cut a lettuce depends on the type:

1. Loose-leaf: pick individual leaves once they reach about 10 cm long. This is true cut-and-come-again. The plant keeps producing new leaves from the centre for several pickings.
2. Hearting types: cut when a firm heart has formed, leaving a 2.5 cm stump in the ground. Many varieties will resprout a second, smaller flush of leaves from that stump.
3. Timing: harvest in the morning, when leaves are at their most crisp and least likely to wilt on the way to the kitchen.

Loose-leaf types are ready in four to six weeks from sowing; hearting types take ten to fourteen weeks. Once a plant starts to send up a central flower stem, harvest immediately. The leaves turn bitter within days of bolting starting, and there's no reversing it.

Tips for Better Results

• Rotate types through the season: loose-leaf and butterhead in spring and autumn when it's cool, crisphead through early summer when bolt-resistance matters most.
• Watch for slugs early: seedlings and young transplants are the most vulnerable stage. Our guide to slugs in the vegetable garden covers barriers and controls that don't rely on pellets.
• Interplant, don't monocrop: a bed of nothing but lettuce is an open invitation to aphids and mildew. Our companion planting guide has combinations that work well alongside salad crops.
• Grey mould and downy mildew show up in cool, humid conditions. The fix is airflow, not fungicide: proper spacing (Step 3) and morning watering (Step 4) prevent most of it before it starts.
• Don't sow into peak summer heat unless you're using a bolt-resistant crisphead or cos variety. In hot spells the soil is often too warm for lettuce seed to germinate reliably in the first place.

Common Questions

Why did my lettuce bolt so fast?

Bolting is triggered by heat and dry conditions. The plant redirects its energy into a flower stalk instead of leaves, and the leaves that remain turn bitter. The fix isn't a different watering schedule after the fact. It's sowing bolt-resistant crisphead or cos types for the hottest sowing window and keeping the soil consistently moist from the start.

Can I grow lettuce in a container?

Yes. A container at least 30 cm wide will hold one hearting plant, or several loose-leaf plants sown closer together for cut-and-come-again picking. Containers dry out faster than open ground, so check them daily once the weather warms.

How do I get lettuce all season instead of one big harvest?

Succession sow: a short row every time the previous one reaches about four true leaves, rather than the whole packet at once. See Step 2.

Next Steps

Once the first sowing is in, the main job is keeping the succession going rather than managing any single plant. For the wider vegetable bed this sits in, our European climate zones guide explains how your region's typical spring and summer temperatures should shift these sowing dates earlier or later.