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.
Except in such places as the Channel Islands, Devonshire and Cornwall, and the milder parts of Ireland, the cultivation of Tomatoes in the open air is attended with a certain amount of risk. The method of growing in Jersey has been already referred to at p. 166. Generally speaking, Tomatoes are a paying crop in the open air in hot summers, but are scarcely worth the trouble in most parts of the kingdom in cold, cheerless, and rainy seasons.
To ensure a fair measure of success the seeds should be sown under glass in March, and the young plants should be grown on as quickly as possible in 5-in. pots, and should be well hardened off, so that by the end of May, or early in June, they will be ready for the open air. The ball of soil round the roots should not be disturbed more than necessary, and if the stem is sunk in the soil almost to the lowest leaf, new rootlets will soon develop from the buried portion of the stem. The plants should be about 18 in. apart in the rows, and these should be 3 ft. apart, or two rows of plants may be 18 in. apart every way, and then a pathway 3 ft. wide should be left between every two rows. This will allow space for tying and for using the hoe frequently on the surface soil. Wherever possible, the rows should run north and south, to secure the maximum amount of light for the leaves and heat for the soil. Each plant should have a bamboo stake about 4 ft. long placed to it at the time of planting. Such stakes will cost from 30s. to 35s. per 1000, but will last for several years with ordinary wear.
Owing to the shortness of the season, only three or four trusses of fruit are allowed to develop and ripen on the plants. Some growers allow two stems instead of one to develop, each one being topped when one or two trusses of fruit have set. It is doubtful if there is any advantage to be gained in this way, as at least one, and probably two trusses of flowers have set on the single stem while the double one is only in the process of development.
Cultivation during the season should consist of a good hoeing at least once a fortnight to crumble the surface soil, to keep down weeds and insect pests, to liberate fresh food, to absorb dews, and, above all, in hot seasons to check evaporation of moisture from the soil. Treated in this way the Tomato plants will grow vigorously and fruit well, and will in all probability be quite free from fungoid diseases if the stock has been raised from healthy seed. In the event of disease appearing, any affected plants should be taken up immediately and burned, and the space in which they stood should be well dusted with flowers of sulphur or watered with a solution of sulphate of copper. It would not be worth while replanting.
The profits to be obtained in good seasons from an acre of outdoor Tomatoes are worth working for. Taking 9000 plants to an acre - and that is quite sufficient - there ought to be no great difficulty in obtaining an average of 3 lb. of fruit from each plant if they are cultivated and not allowed to grow anyhow. This would give a yield of 27,000 lb. to the acre. At 1d. per pound the gross return would be £112, 10s. Allowing £10 for labour, £25 for commission, etc, and £5 for rent and rates, there would be a net profit of £72, 10s. for the four months the plants were being grown. Even if another £20 is deducted from this for raising and early cultivation, there is still a substantial profit of £52 108. for the grower. However, in most parts of the kingdom this can only be expected about once or twice in five years for outdoor Tomatoes.