This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
For early spring Lettuces in the open ground the earliest are the hardy varieties. For Cos Hick's Hardy White, and for Cabbage Stanstead Park or Lees Immense are best. These are sown in late August thinly in drills, and afterwards planted 12 in. by 9 in. in open ground in October. Only light warm soil is suited to them. It is useless to attempt to grow them on soil that is the least heavy and cold.
A little shelter from winter's winds is a great advantage to these crops, and where the land is suitable the planting of shelter hedges would pay. Some people balk or ridge the land up, then level the furrows into gentle slopes to the south and plant two rows on each furrow. It makes the most of the sunshine and shelters from the northerly winds; but in a spring with many frosts and early thaws it is a question whether catching the early sunshine does not do almost as much harm as good.
The next Lettuces to come in are the spring varieties that have been housed in frames all the winter. Sowings for these are commenced in the second week in October, and continued regularly at intervals of a fortnight till the first week in December, after which it is well to desist until the New Year. The soil in the boxes must be made fine, levelled, and firmed before the seed is sown. A 1/2 lb. of sulphate of iron to the square yard of ground may be sown before the soil is finally levelled. It helps the plants to resist the fungus attacks that frequently do great damage in the late winter.
The seed must be distributed evenly, and covered to the depth of 1/2 in. with sifted soot in which some sand and old mortar rubble are good ingredients. After sifting, the soil should be lightly patted. As soon as the seedlings show above ground the lights must be pulled off in fine weather and pushed on when it rains. This operation of pulling off and putting on needs doing several times a day in catchy weather. The lights must be put on at night and blocked up for air except in severe weather.
If the young seedlings show a disposition to "draw", which they will do if the glass is not regularly taken off in fine weather, or if there should be a run of gloom and wet, a good plan is to sift some fine soil evenly over them to "stank" them up. The constant attention to the Lettuce in the lights must be kept up till March. If the weather gets very severe they will need covering with mats at night, but they do not want coddling. When, after all this, the finished article sells in June for 2d. per score, as it frequently does, the market gardener has an opportunity of graduating in the school of which the patriarch Job is said to have been the most distinguished professor.
Planting begins at the end of February or beginning of March, according to the season. Sometimes a fungoid disease called the "drop" attacks the young plants in the lights. It shows itself by a browning of the leg just above ground. The disease spreads rapidly, and a day or two after its appearance patches of the plants will be found flagging. If they are examined, the brown ring will be found to have developed into a patch of dead tissue, cutting off all supplies from the roots to the top. Sprinkling with flowers of sulphur checks the spread a little, but the remedy most favoured is to hurry the plants out into the open fields. The sorts grown are "Fulham White Cos" for the earliest (although this sort appears to be less grown every year); "Paris Cos" - mostly a dark-green variety, at the early sowings, and a white variety after. For Cabbage varieties, "Vauxhall Defiance" and "Chavigny" are good sorts for autumn and winter sowings under lights. For summer work, "White Marvel of Cazard" and "Trocadero" may be tried, the latter for July sowings. The "Malta" and "Webb's Wonderful", two large-growing varieties, are much favoured in the Midlands, but will not sell at all in London.
Cabbage Lettuce during the summer are generally sown in drills 1 ft. apart, and then singled to 12-in. spaces.
The distances for planting are 12 in. by 9 in. for the Fulham Cos, and 15 in. by 1 ft. for the Paris Cos and the Cabbage Lettuces.
If good strains of Cos Lettuce are bought, it will be found that they will heart without the aid of tying, and some growers send them to market untied; but it will be found to pay to put a bit of "fillis" round them, as it preserves their shape and spares the breaking away of the outside leaves. It will not be denied that careful attention to the condition in which stuff is sent to market will always pay the individual grower, besides helping the trade generally. [W. G. L].
Although the estimated area devoted to this crop in Evesham is only 100 to 120 ac, yet the total number of lettuces from that area is a very large one, being planted at the rate of about 174,000 per acre, or 6 in. apart in each direction - the actual number per acre at 6 in. apart being 174,240. One variety is chiefly grown, and that is "Schofield". It is sown early in August, and in September strong plants are ready for planting out, which is done immediately the plums are cleared away. The Lettuce are planted under Plum trees in plantations and belts, on warm borders and in breadths between single or double lines of Plum trees, the earliest usually being gathered from under the trees and from warm borders. Birds are kept down, else serious destruction to Lettuce during winter would take place; and slugs and soot do not harmoniously exist together. [J. U].