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.
The Tomato is not a difficult plant to grow. It will flourish in any good garden soil that is sweet and clean, and contains a fair amount of well-decayed organic material. It is a mistake to have the soil too rich for Tomatoes either in the open air or under glass, as this induces them to develop gross sappy shoots and comparatively little blossom. A sandy loam will give the best results as a general rule. Indeed, the finest crop of Tomatoes I ever saw were grown in a mixture of old potting soil and sifted ashes, which formed the stage in a long greenhouse. From twelve to twenty - four fruits were borne on each truss, each fruit weighing from 3 to 4 oz. - just about the best weight for market purposes.
Perhaps the most convenient method of raising Tomato plants for market work is to sow the seeds in shallow wooden trays - those generally used for cuttings, and measuring about 15 in. long, 9 in. wide, and 2 in. deep. A little rough fibre and half - decayed leaves should be spread over the bottom for drainage and to prevent the finer soil falling through the slit in the bottom. The compost used should be a sandy loam and leaf mould. It should be pressed into the boxes firmly with the fingers to within 1/2 in. of the top. After levelling with a piece of flat board, the seeds should be sown carefully at least 1 in. apart every way, so that each box will hold about one hundred seeds. It is better to sow this way than haphazard, so that when germination takes place each little seedling will have plenty of air and light. The seeds should be covered with about 1/4 in. of soil, which should be pressed down firmly, and levelled with the board. When as many seeds have been sown as are necessary for any particular crop, the boxes should be well watered with a fine-rosed can, and then placed on shelves near the glass. If sowing takes place in January and February or March, the night temperature should not be allowed to fall below 60° F. at night, with a rise to 65° or 70° during the day. If the soil is kept moderately moist, the seeds soon germinate under these conditions, and by keeping them as close to the glass as possible the young plants remain short and sturdy. The less light they get, and the farther away from the glass, the weaker and more drawn they become, and never make such fine plants. Of course, seeds of Tomatoes may be sown in pots or pans of various sizes according to taste or convenience, but other conditions should be the same as described above. By sowing thinly, as described, the young plants need not be moved from the seed boxes or pots until about 3 or 4 in. in height, because they will have plenty of space to develop until then. If the grower has been foolish enough to sow thickly, he will either have to thin out soon after the first true leaves have developed, or he must move the seedlings earlier into small pots; otherwise he runs the risk of spoiling and weakening a large number of plants (fig. 494).
Fig. 494.-Seedling Tomato Plant.