Tomatoes are a valuable addition to even the smallest plot- but they need constant care and lots of light to set fruit and achieve good yield.
Tomatoes can be grown in soil in the glasshouse but problems with disease and soil exhaustion make alternatives a good option. Bottomless pots, placed on gravel in the glasshouse, were widely used and now we have 'grow-bags'. You can still use the bottomless pot method- the pot is watered until the roots have grown down into the gravel when the water is then applied to gravel. Once fruit begin to form on the tomato vine, a high potash fertiliser is applied weekly.
Grow-bags can be bought with soil specially formulated for tomatoes; a hole is cut in the upper part of the bag and the tomato plant planted in it. When the crop is finished the bag and soil can be thrown out (you can dig it into the garden but avoid any area where you intend to grow potatoes the following season).
Alternatively, you can use large individual pots for the tomatoes.
A key factor with glasshouse tomatoes is good ventilation. Don't underestimate how hot it can get unless you allow air circulation. This will also help to reduce the incidence of disease and troublesome moulds. The leaves on the lower trusses are often removed to aid ventilation; but don't remove leave below flowering trusses or you risk losing the fruit set on these branches.
Remove lower leaves as they yellow and die.
Outside tomatoes can be grown in a sunny, open position with fertile, well-drained soil, or in a hot corner where there is room for a 'grow bag'.
Plant the seedling plants 0.4m apart in soil to which organic compost and a handful of balanced NPK fertiliser or blood, fish and bone meal have been added.
Outdoor tomatoes need regular watering and feeding with liquid tomato fertiliser, especially when grown in containers.
Smaller, cherry tomatoes are popular for courtyard and small gardens - they look great and the fruit are sweet and marvellous for salads. Plant these 0.4-0.5m apart, in the garden or into a grow-bag. You can even grow them on a balcony if you are diligent in watering.
Seedling tomato plants come into the plant nurseries from August onwards. Different varieties are better suited to indoor, glasshouse culture and growing outdoors. If you are not familiar with the varieties on offer, ask the sales staff.
Labour Weekend has long been considered best time for planting outdoor tomatoes, although this will depend on your local climate.
Remember when setting out the seedling plants that they grow in a temperature range of 21-24 degrees C, and that anything below 12 degrees C (and over 27 degrees C) will result in damage to the plant. You can guard against a late cold snap or frost by placing a cage over each plant and covering it with a row cover.
Water newly plants tomatoes in thoroughly, then leave for a week to encourage the roots to seek out water and develop a strong and extensive root system.
Perfect, tasty tomatoes
Problems, Pests and Diseases
- Blossom end rot- fruit have blackened ends where the blossom was. Caused by over or inconsistent watering
- Fruit splitting- common on outdoor fruit or that which has been over watered.
- Botrytis- a grey mould on fruit caused by humidity and lack of ventilation
- White Fly- Hanging a yellow card covered with grease will attract and trap these (they are strongly attracted to yellow). Derris dust can also be used, but with caution as residues will remain on the fruit.
- Aphid- Plant tagetes (marigolds) attract aphid predators. Alternatively squash aphids by hand, remove with a strong jet of water or spray (but remember that you intend to eat the fruit!)
Well staked outdoor tomatoes
The same tomatoes beginning to ripen
Fruit split problems develop into mould