Greenhouse Plants – Growing Tomatoes (Lycopersicon)
This site gives information on growing and caring for a variety of specific plants, including half-hardy summer vegetables, winter vegetables and salads, herbs, fruits, and flowers.
Half-hardy summer vegetables
Half-hardy vegetables that are slow to mature, such as peppers, aubergines,, and tomatoes, need space in the greenhouse all summer to give a worthwhile crop. Others, such as and , start to crop quickly and can be cleared when outdoor crops are ready.
In both cases, the plants must be started off when the temperature outside is still cold, so you will need to provide some heat to raise them yourself. The alternative is to buy plants in at planting time.
Growing Tomatoes – Lycopersicon lycopersicum
There is a wide choice: from small cherry to large beefsteak fruit, with red, yellow, or striped skins. You do not need a special greenhouse variety — all generally grow better in a greenhouse than outside, and those described as outdoor tomatoes may be the best choice for greenhouse-growing in cold areas.
Some modern varieties are bred for disease resistance and may be worth considering if you have trouble with root rots or viral diseases. Upright, cordon varieties give the best value for space in a greenhouse border, but bush varieties are useful, for example, in hanging baskets and in pots on the bench.
Sow seeds in one pot for pricking out, or in small (3cm) individual pots, approximately eight weeks before planting Aim for a temperature of about 18°C for germinating the seeds and bringing on young plants for the first few weeks.
Plant out as soon as conditions are at least frost-free andtemperatures are above 10°C — usually sometime in late spring in an unheated greenhouse. Tomatoes do best in a well-manured or composted greenhouse border, planted 45cm apart. However, you can get good yields by growing them in 25-30cm pots, or by ring culture, provided that enough attention is given to feeding and watering.
Tall varieties need supporting with canes or string right from the start, and also need all their side shoots pinching out. Bush varieties need no such training. Tomatoes need good light and well-ventilated airy conditions. Do not let the soil dry out.
Harvest from mid-summer to mid-autumn. Pick the ripe fruit regularly to encourage more to be produced.
Pests, diseases, and disorders
The main pests of tomatoes are whitefly, aphids, tomato moth, and root eelworm; they are also subject to various foot and stem rots and viruses. The most common disorders are magnesium deficiency, leaf curl, and blossom end rot. Good husbandry should avoid most of these problems.