How to Grow Lettuce from Seed: Sowing, Succession & Bolting

Lettuce is a fast, forgiving crop that you can grow from seed almost year-round with a little planning — the main trick is that it is a cool-season plant that dislikes heat. Sow little and often and you can pick fresh leaves for months.

When to sow

Lettuce grows best in the cooler halves of the year — spring and autumn — and in mild spells over winter under cover. In summer heat it struggles to germinate and runs to seed, so time main sowings for cooler weather or grow heat-tolerant types in light shade.

Seed depth and temperature

Sow seed shallowly, only about 0.5 cm deep, and firm gently — lettuce seed needs light and cool soil to germinate well. Above roughly 25 °C many varieties enter thermodormancy and simply will not germinate, which is why summer sowings fail; sowing in the cool of the evening, or starting seed somewhere cooler, solves it.

Direct sow or start in modules

You can sow thinly straight into the ground or into module trays to transplant. Modules give tidy, evenly spaced plants and dodge slug damage at the vulnerable seedling stage; direct sowing suits cut-and-come-again leaf lettuce.

Succession sowing

The secret to a steady supply is succession sowing — a short row or a few modules every couple of weeks — rather than one big sowing that all matures (and bolts) at once.

Thinning and spacing

Thin or plant leaf lettuces to about 15 cm apart and hearting types (cos, butterhead, crisphead) to 25–30 cm so they can form heads. Crowded plants stay small and are more prone to disease.

Common problems

Bolting (running to seed, turning bitter) is triggered by heat and stress — keep plants cool and evenly watered and choose bolt-resistant varieties for summer. Slugs and snails devastate seedlings. Downy mildew and rots appear in crowded, damp conditions, and tip burn (brown leaf edges) follows erratic watering. Aphids can shelter in hearts.

Harvesting

Pick loose-leaf types as cut-and-come-again, taking outer leaves and letting the centre regrow, or cut hearting types whole once firm. Harvest in the cool of the morning for the crispest leaves. For starting seed reliably, see seed germination; if seedlings collapse at the base, see damping-off.

Types of lettuce and how they differ

Choosing the type shapes how you grow and harvest. Loose-leaf lettuces (such as Salad Bowl types) form no heart and are picked leaf by leaf — the most productive and cut-and-come-again friendly. Cos/romaine stands upright with crisp, sweet leaves. Butterhead forms a soft, loose heart and matures quickly. Crisphead/iceberg forms a tight, crunchy head, takes longest, and is the fussiest about heat and spacing. For continuous picking, loose-leaf and cos are the easiest.

Growing through winter and under cover

In mild areas and under cloches, cold frames or an unheated greenhouse, hardy winter lettuces can supply leaves through the cold months when sown in autumn. Growth is slow in low light, so space plants well and ventilate to keep grey mould at bay.

Containers, baby leaf and microgreens

Lettuce has shallow roots and grows happily in pots, troughs and windowboxes. For the fastest returns, sow densely and harvest young as baby-leaf salad, or sow thickly in a shallow tray and cut at the seedling stage as microgreens within a couple of weeks — both sidestep the spacing and bolting concerns of full-size plants.

Watering and feeding

Lettuce is mostly water and needs a steady supply to grow fast and sweet; let it dry out and it turns bitter and bolts. Water regularly, ideally in the morning and at the base to keep leaves dry and discourage disease. In decent soil it needs little feeding, but a nitrogen-rich boost keeps leaf types cropping.

Beating summer heat

Because heat is lettuce’s enemy — stopping germination and triggering bitterness and bolting — summer growing is all about keeping plants cool. Sow in the cooler evening hours, grow summer crops in the light shade of taller plants or on a shadier side of the garden, choose varieties described as slow-to-bolt or heat-tolerant, and never let the soil dry out. Frequent small sowings of loose-leaf types picked young as baby leaf will often succeed through summer when full-hearting types fail. As autumn cools, hearting varieties come into their own again.

Saving your own seed

Lettuce is self-pollinating and easy to save seed from: let one good, healthy plant bolt and flower, and it will produce fluffy seed heads. Gather the seed once it dries on the plant, and store it somewhere cool and dry — lettuce seed stays viable for several years. Saving seed from your best-performing, slowest-to-bolt plants gradually gives you a strain suited to your own conditions.

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Part of our Vegetable Gardening guides.