With the right care and attention and by sowing the appropriate varieties, you can have
Lettuces virtually all year round. There are four main types of lettuce. Cos or Romaine varieties, like Little Gem which have more upright growth and crisp leaves. Butterhead types are generally the most popular, having more tolerance towards poorer conditions. They have soft leaves and are quick to mature. Crisphead varieties, like Iceberg and Webbs Wonderful are more resistant to bolting than Butterheads and are the most popular type in the US. Loose leaf or 'Cut and Come Again' lettuce are all the rage and make perfect container crops as they do not need much space between the plants. You can grow several varieties together to have your own growing mixed salad bowl.
Soil & Growing Position
Lettuces need a well-drained, fertile and moist soil. Dig in autumn, adding in compost or manure. Test your soil to see if it's acidic and if so, incorporate some lime. Shortly before planting or sowing, rake in Growmore. Summer lettuces should be grown in sun or part shade and spring lettuces need a sunny protected spot if they are not to be grown in a greenhouse or polytunnel.
Sowing from Seed
Lettuces do not like to be moved, prefering to be sown where they are to grow. Sow every two weeks for a succession of lettuces throughout the season. Do not sow all the seed in one go as you will have a glut. Sow seed thinly at a half inch depth in rows 12" apart.
If you are starting them off under glass, sow 2 seeds in a 3" peat pot, removing the weaker seedling.
For a summer/autumn crops, sow under glass in February for planting out in March under cloches/growing tunnels or sow outdoors every two weeks from late March up to late July.
Early winter crops are sown outdoors in August and covered with growing tunnels or cloches (with enclosed ends) from late September.
Mid winter crops are sown under glass in September/October and planted out once the seedlings are large enough to handle.
For Spring crops, choose a winter hardy variety and sow outdoors if you live in a mild area in August/September, thinning in October to 3" and continuing thinning in the spring to achieve 12" apart. In colder regions, sow in mid October under cloches or growing tunnels.
Growing On & Young Plants
Overcrowding must be avoided so start thinning as soon as the first true leaves appear and thinning should continue until the plants are 12" apart. Smaller varieties and Little Gem can be spaced at 9" apart, whilst loose leaf need only a few inches. You can try transplanting thinnings, taking care not to bury the lower leaves.
Plants started off under glass will need hardening off before planting out. Put in a coldframe or cool porch for a few days.
Crop Care
Birds can be a nuisance so use netting. Slugs are also a pest so use pellets or your preferred slug deterrant method. Keep on top of the weeds. Greenfly can be a nuisance and render the crop inedible so use preventative measures such as sticky yellow traps in the greenhouse and insect mesh outside. If the crop is affected, you will need to spray.
Greenhouses will need good ventilation through the summer. Greenhouse lettuces need their soil to be slightly on the dry side whilst outdoor crops can be watered more liberally. Watering is best done in the morning as more disease occurs as a result of evening watering.
Harvesting
Loose leaf lettuce can be cut as soon as it is large enough to eat. Lettuces are ready once a firm heart has formed. It is important to cut at this stage before the heart starts to grow upwards as this a sign that the plant is preparing to bolt. Cut in the morning when there is still dew on the lettuces. The whole plant should be pulled up and the roots and lower leaves cut off.
Summer/Autumn lettuces are ready for harvesting from June to October.
Early winter crops are ready in November/December.
Midwinter crops run from January to early March.
Spring crops harvest in April/May.
