The best results are obtained by sowing the seed in rich, well-manured soil where the plants are to grow. There are two main types of lettuce, cabbage, and cos, but many varieties of both. Tall, short, dwarf, “butterhead” “iceberg” “loose leaf” and many more, all shades of green and even red make up the varieties.
Summer Cabbage Lettuce
The soil should be prepared in the previous autumn. Add plenty of organic matter to the soil at the rate of 2 bucketfuls to the sq.yd.
A week before sowing fork in a little peat at a rate of 1 bucketful to the sq. yd. This will help the soil to be light with a good texture suitable for growing lettuce. Add fish and bone meal at 4 oz. (120g) to the sq. yd. If the ground is not chalky also add carbonate of lime over the surface at 5 oz. (150g) to the sq. yd.
In the south seed can be sown from the middle of March and a little later in the north in drills 1 ft. apart and at a depth of ½ in. (12mm) make sowings every 14 days until the middle of July; this will ensure a succession of well-hearted lettuce.
Seed can be sown in trays in a greenhouse at a temperature of 55 deg F. (13deg. C.) in January if a very early crop is required. They can be transplanted out when they are big enough to be grown on under cloches; by early March they may be set out in rows 9 in. (228mm) apart.
During dry weather water well, thin out the plants where necessary as early as possible allowing 9 in. (228mm) between each plant. Small or dwarf varieties need to be thinned out to only 6 in. (15cm) apart.
Cut those lettuces with fully developed hearts early in the morning using a sharp knife making the cut just below the bottom leaves. Remove all those that have started to bolt or they will run to seed.
Winter Cabbage Lettuces
Lettuces that are grown through winter need well-drained soil; therefore light, a sandy loam is best but raised beds are an option. They require shelter and are a suitable crop to grow in the same soil that was well manured for a previous crop, such as potatoes.
The only preparation required is to rake the soil over apply fish manure with a 10 percent potash content at the rate of 3 oz. (90g) to the sq. yd. Bonemeal may be used instead with added wood ash at 6 to 7 oz. (210g) to the sq. yd.
Seeds should be sown in rows 1 ft. apart and not more than ½ in. (12mm) deep in early September. Sow thinly, the resultant plants should be allowed 5 in. (127mm) between each plant, ensure that any thinning out is done before the winter sets in.
If during the time of sowing, the ground where they are to grow is not yet ready, being occupied by another crop, the seeds can be sown in trays until the time comes to plant them into their true position. Cloches should be placed over the plants to give them protection during the long winter months.
Keep the soil free from weeds. Early March of the following year dried blood may be given at 5 oz. (150g) to the sq. yd. This should be applied between each row taking care not to put any onto the plants.
The lettuces can be cut as soon as they are ready and when they are required, the first should normally be ready about May or June.