Tomatoes (Solanum lycopersicum) are the taste of summer - here's how to sow, grow and enjoy!
How to sow
Sow tomatoes indoors eight to ten weeks before your last frost date. The temperature of the compost should be approx 20- 22C for the seeds to germinate. A propagator or heat mat is very useful here.At lower temperatures germination will take a little longer. Try to keep temperatures from fluctuating too much during he early stages of growth. Tomatoes can be sown in seed trays, modular trays or mini blocks and pricked out to larger 10cm pots after the third leaf has formed. Seeds should be sown 2cm deep in seed compost and potted on into potting compost.
Seeds grown in a warm place will race ahead – but if your light levels are low they will become weak and leggy. To stop this happening you should
reduce the heat to about 10C and put your plants in the brightest place possible. The best tomato seedlings are short and stubby rather than tall and thin. If your tomatoes are a bit leggy you can still use them by planting quite deep - right up to the lower sets of leaves. Tomato stems have the ability to grow roots from buried stems and will build a more extensive root.
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Watering should be as consistent as possible. Make sure that you sow seeds into moist growing medium. Always water tomato seedlings from below, taking care not to over water or allow your tomato seedlings to dry out.
Tomatoes should be transplanted into their final positions when they are about 15cm high. Do not leave it too late or the roots will have become pot bound. Whilst tomatoes can be grown outside in very sheltered positions best results are obtained through protected planting in a polytunnel or glasshouse. If you do chose to plant outside you must harden the plant off for at least two weeks before planting out in their final position.
Tomatoes require very fertile soil. Incorporate well rotted farmyard manure or a quality NPK fertilizer into well prepared soil. Seaweed dust should also be utilized – the plant hormones in seaweed are very beneficial to tomatoes.
Dig a hole for each plant 5cm deeper than the pot, rows 45cm apart. Planting tomato plants deeper in the soil than in the pot will encourage the formation of additional roots. Water well if conditions are at all dry.
Tomatoes need support – either canes or strong twine. If you are using twine it must be strong to take the considerable weight of your crop. This can be done by burying a length of twine under the root and tying the other end to the crop bars in your tunnel.
Tomato After Care
Tomatoes produce lateral branches or side shoots and these must be nipped out so that all the plant's energy goes into growing fruit. The side shoot will appear at the point where a leaf branch meets the main stem. When growing in a greenhouse or polytunnel keep well ventilated especially on hot days to prevent the build up of pests and disease. If fruit is slow to set in early summer then tap the plant support to encourage the spread of pollen.
Stopping is the practice of removing the main growing tip to prevent further fruit truss formation and to encourage existing fruits to ripen. To stop plants cut off the top of the main stem - continue to remove side shoots as normal. For polytunnel growing stop the plant when seven or eight trusses have formed; but in a cold year it is best to limit this to five or six.
Water well when planting out and then lightly until the fruit starts to set. Once fruit is setting water well on a weekly basis. Keeping plants slightly on the dry side is said to intensify flavour.
- Roots are unable to absorb nutrients when the temperature is cold. This can be a cause of blossom end rot.
- Fruit Splitting – This is caused by irregular watering. A regular watering regime with an irrigation system and timer will solve this and save time.
- Calcium Deficiency & Blossom End Rot - Blossom end rot is a dark and often rotting area around the base of tomato fruits and is caused by a shortage of calcium. The problem may be under watering as calcium uptake is slowed in drought conditions. Again, a more regular watering regime should solve this problem.
- Whitefly and aphids are the most likely pests to affect your tomatoes. As soon as you see eggs, try spraying with water to wash them off and remove others by hand. You could also use yellow stick traps to trap the insects. Herfosec Plant Strengthener can also be used to strenthen the plants whilst at the same time discouraging biting insects.
- Tomato Blight - This is caused by the fungus Phytophthora infestans which is also the cause of potato blight. This is not normally a problem if plants are in a polytunnel. However, if the polytunnel is not properly ventilated wet foliage can allow infection, which is often fast spreading. Make sure that plants are well spaced out allowing for airflow. Do not use overhead irrigation for tomatoes.
Pick as soon as the fruits are ripe for the best flavour - eat as soon as possible. This also encourages the production of more fruit. As soon as a frost threatens in October/November, harvest all the fruit immediately and ripen them on a window sill.
Wash and dry your tomatoes before storing at room temperature. Store in cooler conditions for up to a month. End of summer gluts can be made into chutnies or boiled up with onions and garlic to make a quick tomato sauce that can be frozen for winter use. Cherry tomatoes can be 'sun dried' in a dehydrator for winter use.