Sla

Lactuca sativa

Engels: Lettuce

vegetableAsteraceaeEetbaar

Sla (Lactuca sativa) is a edible vegetable from the Asteraceae family that grows up to 30cm tall. This plant thrives in full sun to partial shade and requires moderate maintenance.

Hoogte

15–30 cm

Breedte

20–30 cm

Zonligging

full sun, partial shade

Waterbehoefte

high water needs

Grondsoort

loam, clay soil

Onderhoud

moderate maintenance

Verzorgingskalender

Taak	Jan	Feb	Mrt	Apr	Mei	Jun	Jul	Aug	Sep	Okt	Nov	Dec
🌱Planten
💧Bemesten
🍎Oogsten

Care tips

Planting

Lettuce thrives in full sun or partial shade, making it one of the most flexible salad crops for temperate gardens. In spring and autumn, choose a sunny spot; in midsummer, partial shade helps prevent bolting. The soil should be moisture-retentive loam or clay, enriched with well-rotted compost or manure dug in a few weeks before sowing. Lettuce has shallow roots and needs consistent moisture, so good soil preparation is essential. You can sow lettuce directly outdoors from March through to August, allowing for a long harvest season. For early spring sowings in March, wait until the soil has warmed slightly and consider using cloches or fleece to protect young seedlings from late frosts. Sow seeds thinly in shallow drills about 1 cm deep, in rows 25–30 cm apart. Alternatively, broadcast seed in blocks for a cut-and-come-again crop. Thin seedlings progressively as they grow. When they're large enough to handle, thin to about 10 cm apart, then thin again to a final spacing of 25 cm for hearting varieties. You can eat the thinnings. For a continuous supply, sow a short row every two to three weeks rather than a large batch all at once. Water the drill before sowing if the soil is dry, then water gently after sowing to settle the seeds. Keep the soil consistently moist during germination, which typically takes seven to fourteen days depending on temperature. Mulch lightly around young plants with compost to retain moisture and suppress weeds, but keep mulch clear of the leaves to avoid rot.

Pruning

Lettuce does not require pruning in the conventional sense, as it is a fast-growing annual vegetable harvested for its leaves. There are no pruning months listed for this crop because you manage it through harvesting rather than cutting back for shape or health. However, you do need to remove any damaged, yellowing, or slug-damaged outer leaves regularly throughout the growing season. This tidying improves air circulation around the plant, reducing the risk of fungal diseases such as downy mildew and grey mould, both of which thrive in damp, crowded conditions. Simply pinch or cut away affected leaves at the base using clean fingers or a small pair of scissors. For loose-leaf and cut-and-come-again varieties, harvest by cutting leaves about 2–3 cm above the base of the plant, leaving the growing point intact so it regrows for a second or even third cut. Use a sharp knife or scissors and harvest in the morning when leaves are crisp. You can begin this selective harvesting as soon as leaves are large enough to use, typically four to six weeks after sowing. For hearting types such as butterhead or iceberg, you harvest the entire plant by cutting at soil level once the heart feels firm. If you notice a central stem beginning to elongate and flower buds forming—a process called bolting—harvest immediately. Once bolting starts, leaves become bitter and the plant is past its best. Bolting is triggered by heat and long days, so mid-summer sowings are particularly prone. Removing any bolting plants promptly prevents them from shading neighbours and allows you to replant the space.

Maintenance

Lettuce has high water needs and shallow roots, so consistent watering is the single most important maintenance task. In dry weather, water daily or every other day, aiming for the soil rather than the leaves to reduce disease risk. In spring and autumn, two to three times a week is usually sufficient. Mulching with a thin layer of compost or well-rotted manure helps retain moisture and keeps roots cool, which is especially valuable in summer. Feed lettuce lightly in April and May if your soil is not particularly rich. A balanced liquid fertiliser applied every two to three weeks, or a top-dressing of pelleted poultry manure, encourages steady leafy growth. Avoid high-nitrogen feeds late in the season, as they can promote soft, disease-prone growth. If you've prepared the soil well with compost, additional feeding is often unnecessary. Lettuce is hardy to zone 4a, so it tolerates light frosts, but growth slows significantly below 5°C. Protect early spring and late autumn crops with cloches, fleece, or a cold frame to extend the season. In winter, you can grow hardy varieties under cover for fresh leaves, though growth will be slow. Slugs and snails are the primary pests, especially on young plants. Check regularly in the evening and use barriers, traps, or organic pellets. Aphids occasionally cluster on the undersides of leaves; wash them off with water or tolerate low numbers, as they rarely cause serious harm. Downy mildew appears as yellow patches on leaves with grey mould beneath, particularly in cool, damp conditions—improve spacing and air flow, and avoid overhead watering. Lettuce root aphid can cause wilting; rotate crops and avoid replanting lettuce in the same spot year after year.