How to Sow and Grow Lettuce: A Complete Guide

Lettuce is quick, productive and suited to beds, containers and gaps between slower crops. The challenge is not germination alone but maintaining a steady supply without gluts or gaps. Sow small quantities often, keep roots cool and moist, and choose varieties for the season.

Choosing lettuce types

Loose-leaf and cut-and-come-again lettuces crop quickly. Butterhead and crisphead types form hearts; cos or romaine varieties are upright and robust. Miniature lettuces suit containers and close spacing. Use cold-tolerant varieties for early and late crops and bolt-resistant varieties for summer.

When to sow lettuce

Sow under cover from late winter, then outdoors from early spring to early autumn in cool climates. Make a short row or small module sowing every two to three weeks. Lettuce germinates best at roughly 10–20°C and can become erratic above 25°C, so sow summer batches in evening, shade trays and choose a cooler position. In hot climates, grow lettuce mainly in the cool season.

How to sow

Sow very thinly, about 5 mm deep, in fine, moist soil. For modules, place two or three seeds per cell and thin to the strongest seedling. Keep compost moist with gentle watering. Direct-sown rows can be thinned to 20–30 cm for hearting lettuces or 10–15 cm for small loose-leaf types. Use thinnings in salads.

Planting and containers

Transplant when plants have several true leaves, setting them at the same depth and spacing for their mature size. Harden off protected seedlings first. Lettuce grows well in pots 15–20 cm deep; ensure drainage and use peat-free compost. In summer, afternoon shade reduces stress and bitterness.

Watering and feeding

Keep moisture consistent. Drying out encourages bitter leaves, tipburn and premature bolting; waterlogging encourages root disease. Water soil rather than hearts where possible. Fertile ground enriched with mature compost usually needs no extra feed. Container crops can receive a half-strength organic liquid feed if leaves become pale.

Common problems

• Slugs and snails: inspect after dark, use barriers and avoid leaving trays or boards nearby.

• Aphids: check inside hearts, wash off colonies and encourage beneficial insects.

• Bolting: caused by heat, long days, crowding or drought; sow season-appropriate varieties and keep roots cool.

• Bottom rot and mildew: improve airflow, avoid saturated soil and rotate salad crops.

• Birds: cover young plants with securely fixed mesh.

Harvesting lettuce

Harvest in the cool of morning. Cut whole heads at the base, pick outer leaves as required, or shear cut-and-come-again crops 2–3 cm above the growing point for regrowth. Wash and dry leaves, then refrigerate in a covered container. Remove any plant that begins forming a tall flower stalk because quality will decline quickly.

Keeping a continuous supply

Instead of sowing an entire packet, sow only what you will eat in two weeks and repeat. Use modules to replace harvested plants promptly. Shift from sun in spring to partial shade in summer and back to brighter, protected conditions in autumn.