There are two main types of lettuce, the cabbage and the cos, and a great many varieties of each differing in color, crispness, size and season.

Lettuces like a well-dug, rather rich, well-manured soil. They are frequently treated purely as a catch-crop, and good yields can be obtained from sowings made on the ridges of celery trenches or between rows of peas. For earliest crops a sowing can be made in pots or boxes of sandy soil under glass in February, prick out the seedlings as soon as they can be handled and plant out in a sheltered place in late March or early April when thoroughly hardened.

Outdoor sowings can be made at fortnightly intervals from early March onwards until mid-August (see below for details of a later sowing). Seedlings can be thinned where they stand and thinnings can be transplanted elsewhere to give a slightly later supply. Space the large varieties 1ft. apart in rows 1ft. apart; small varieties such as Tom Thumb 8in. apart in rows 1ft. apart.

Selected varieties are available for sowing in late August or early September in the open garden to reach maturity in early spring. Plant the seedlings out 9in. apart in rows 12in. apart in early October. These should be grown in a warm, sheltered border. Slug pellets will need to be put down the rows in late autumn and early spring. If some of the plants are covered with cloches, cuttings can be advanced. Other varieties can be sown at the same time for winter cultivation in greenhouse or frame.

Indoor cultivation

There is nothing better than a crisp, fresh lettuce as the basis of a salad or as a side dish to accompany meat, egg and pasta dishes. Indoor cultivation provides an extended season of home-grown produce.

Lettuces for indoor growing can be divided into three main categories - cabbage (heading) lettuce, cos (romaine) lettuce and non-hearting loose-leaf types, also called salad bowl varieties. I recommend growing some of each kind, if space allows. This provides the greatest variation of taste and texture. Lettuce, like most other green vegetables, starts to lose its vitamin content almost as soon as it has been cut, so not only do you obtain the best flavour from lettuce culled only minutes before eating, it also contributes more goodness to your diet.

With experience, it will become apparent how much seed to sow at one time to produce the size of crop which you can readily use while it is still in the best condition. However, if early efforts result in a glut of lettuces, don't forget that it can be eaten cooked - lightly boiled, stir-fried with other vegetables, or made into a cool-tasting soup. Once you have established a good crop, it is worth checking recipe books to find out how versatile lettuce can be as an ingredient of hot and cold dishes. The golden rule is not to overcook, by whatever method, as cooking destroys the nutrients very quickly.

Selecting lettuces for indoor growing

There is a great variety of lettuces and your choice may depend to some extent upon the space which you wish to give to this particular crop. Little Gem is an excellent cos lettuce which matures quickly and has a sweet taste. In the open garden, this can grow to quite a size; in containers indoors it does not achieve such size and is a manageable and productive plant. If you have room to grow lettuces in large tubs, there is a larger cos, Lobjoit's Green, which has a crisp texture and rich colour, a popular gardener's choice worth trying for container growing. Among the cabbage lettuces, my recommended varieties for indoor growing are Tom Thumb and All the Year Round. Tom Thumb is a nicely compact plant, fast to mature and well-flavoured. All the Year

Round is a medium-sized lettuce less likely than others to bolt (run to seed) if you forget to water for a short period. Bibb is an American variety which takes 65 days to mature and is of a good size for container growing.

Loose-leaf varieties include the green and red Salad Bowl varieties which produce a more open habit of growth without central hearting. You can simply pick the leaves a few at a time as they are needed. The red-tinged leaves are a pleasant variation for inclusion in mixed salads.

Sowing and germination

Indoors, you can start lettuces from seed as winter turns to spring. Even 'All The Year Round', despite its name, cannot be expected to produce a perfect crop during dark days with the risk of low night-time temperatures, but if you can provide stable conditions and the brightest possible location, it is worth trying a late autumn sowing which will produce a winter harvest.

Lettuces are undemanding as to soil type, but this does not mean you should sow in a poor equality potting mixture or recycle exhausted soil. If you have a garden, an economical growing medium is garden soil sifted together with a commercially-produced potting mixture. Peat is not necessary, but a small amount of sand can be added to aid drainage. Alternatively, you can simply use a commercial soil-based or universal potting medium, or any mixture of your own which has produced successful results with other crops.

Unlike some other vegetables, lettuces do not need a great depth of soil, since their roots are not very long. Shallow containers can be used, and standard seed trays are adequate for sowing and growing on the plants. But do not crowd a lot of seedlings together in a small tray; the smaller lettuce varieties should be thinned or transplanted to about 6in (15cm) apart. If you are growing the larger types, such as Lobjoit's Green, provide deeper containers and more lateral space for the plants to develop.

The soil should be just moist when the seeds are sown. Fill the trays and firm the soil lightly; then spray very sparingly with tepid water from a hand spray. Lettuce seeds are quite small, so do not waste time trying to space them evenly as you sow - the seedlings can be thinned out later. Scatter the seed thinly and cover with a fine layer of the potting mixture, about 1/4in (5mm) deep. If you have very little space and want to avoid any wastage, you can sow pelleted seeds which can be placed accurately at intervals across the soil surface; however, this is a more expensive way of buying seed, and you will have fewer plants for your money. Packets of loose seed are comparatively better value as you can make several small succession sowings from one packet.

Growing on

When the seedlings are large enough to handle, thin out the weaklings or transplant a proportion of them into other containers leaving the required space for the remaining plants to grow on. Alternatively, the seedlings can all be left to grow larger and the thinnings can be taken when they are at a suitable size to provide very tender young leaves for salad use; but don't leave this so late that the remaining plants are inhibited from maturing to full size.

Lettuces take from eight to twelve weeks to come to maturity, depending on the cultivar and the growing conditions. They require a good deal of water and quickly wilt if deprived of adequate moisture. Keep them in mild or warm conditions; being tender-leaved, lettuces should not be exposed to strong sunshine when grown indoors, as there is the risk of scorching. If they grow in a window which receives full sun all day, shade the plants with newspaper or draw the curtains temporarily while the sun is at its height.

Water the young plants regularly to keep the soil moist. As the lettuces become well established, a good soaking does more good than continual sprinklings of water, as the moisture must reach the finest branches of the root system and carry nutrients from the growing medium to the extremities of the roots. After about six weeks of growth, the plants benefit from a liquid feed every ten days or so. Overfeeding does not encourage more rapid growth; strong doses of fertilizer do more harm than good, so check the manufacturer's instructions on dilution of the fertilizer.

Lettuces are highly attractive to slugs and snails, so be vigilant if you leave the windows open or stand the plants outside during fine weather. Check the plants, the soil surface and the outside of the container to make sure there are no damaging pests attached.

Harvesting

Cut cabbage and cos lettuces when a firm heart has formed but take note that is is the darker coloured outer leaves which contain the most minerals and other nutrients, so don't discard these. Trim off any bruised or discoloured sections and cut or shred the remainder for inclusion in salads. Harvest the leaves of loose-leaved varieties as and when they are needed; continual small cullings encourage production of new growth.

Top a lettuce leaf with a slice of turkey, cucumber, hummus and paprika, then, as if it were a sandwich, wrap it up with another piece of lettuce.
Repeat with the remaining ingredients.

 This can be done with a variety of ingredients, such as tomatoes, avocados or peppers, as well as salmon, chicken, lamb or prawns.
White cheeses, herbs, garlic, lemon juice, paprika, turmeric, oregano, all work too. Whatever you have in your fridge!