Choose the right varieties and you can have lettuce almost all year round. There are so many types of lettuce to choose from – all with different colours, flavours and textures – that salad need never be boring! There are two main types of lettuce – hearting lettuces have a dense centre, while loose-leaf lettuces have open leaves and no heart. You can also grow a variety of salad leaves that can be picked while young and tender.
Grow lettuces in full sun on moisture-retentive soil. Early and late sowings may need protection against cold, using cloches, plastic tunnels or horticultural fleece. All these types of protection will be available at garden centres.
There are several different types of hearting lettuces:
- Butterhead lettuces have an open habit, are quick-maturing and tolerate poorer growing conditions.
- Cos types have an upright growth habit and oblong head.
- Crisphead types produce large hearts of curled and crisp leaves and are more resistant to bolting (going to seed prematurely); this group includes iceberg lettuces.
Sow a short row every fortnight to ensure continuity of cropping. Sow seed thinly 13mm (½in) deep in rows 30cm (12in) apart.
You could also grow lettuces in growbags or containers – follow the sowing timings and spacings as below.
Time of sowing depends on when the crop is wanted:
- For a summer/autumn crop: sow outdoors from late March to late July. For an even earlier crop, sow indoors in early February in seed trays and plant out in early March under cloches or plastic tunnels.
- For an early winter crop: sow outdoors in early August and cover the plants with closed cloches in late September.
- For a spring crop: sow a cultivar such as ‘Winter Density’ in September/October either in a cold greenhouse or outside under cloches in mild areas.
High soil temperatures in summer can prevent some cultivars from germinating. Sow in the evening, water with cold water and provide some shade to keep temperatures down.
Thin seedlings as soon as the first true leaves appear and continue until the plants are 30cm (12in) apart. The seedlings you thin out can be washed and eaten too.
Water when the soil is dry; the best time to water is in the early morning.
Early in the year sparrows can be a problem as they find young lettuce plants irresistible. Protect with fleece, chicken wire or similar.
Troubleshooting Growing Problems
Lettuce root aphid: Older plants suddenly wilt and die back, usually in mid- to late sunmmer. You may not see the aphids, as they attack the roots, not leaves, but you may see lots of ants around the plants, as they feed on the honeydew that the aphids produce.
Remedy: The damage is worse in dry conditions, so keep lettuce well-watered. If you suspect root aphid and only have a few lettuces, you can pull them up, wash off the aphids and replant in fresh compost. Otherwise, there is not much you can do, except pull up any affected plants and destroy them. Prevention is the best cure, so cover lettuces with insect-proof mesh (like Enviromesh) from June until August as this will prevent aphids getting to the roots. Some lettuces are resistant to root aphid.
Slugs and snails: These feed on the young seedlings and you’ll see the tell tale slime trail on the soil around your crop, as well as on the leaves.
Remedy: There are many ways to control slugs and snails, including beer traps, sawdust or eggshell barriers, copper tape and biocontrols.
Grey mould: Can be a problem in densely sown crops, especially ‘cut and come again’ veg crops. Seedlings suddenly collapse. This is a problem normally in wet conditions, and is usually worse on weak or damaged plants. The mould usually enters through a wound but, under the right conditions, even healthy plants will be infected. You will see fuzzy grey mould on affected buds, leaves, flowers or fruit. Infected plant parts eventually shrivel and die.
Remedy: Sow thinly and when conditions are warm. Hygiene is very important in preventing the spread of grey mould. If you see it, remove the infected material and destroy. Grey mould is encouraged by overcrowding, so make sure you plant your seedlings, plants and squashes at the appropriate distance apart.
Bolting: Plants flower and set seed prematurely.
Remedy: Unless growing for seed sow bolt-resistant varieties. Sow or plant at the correct time and keep the soil or compost moist.
Lettuce is ready to cut when a firm heart has formed, or the for loose-leaf varieties when leaves are big enough to be worth eating. Harvest lettuces by cutting rather than pulling.
Plant with: beets, broccoli, brussels sprouts, cabbage, carrots, cauliflower, chinese cabbage, chives, garlic, kale, kohlrabi, onions, radishes, strawberries