How to grow tomatoes on the allotment

Although tomatoes need a little more care and attention than some crops they aren’t difficult to grow and offer great rewards for your effort. They come in a range of sizes from grape-sized cherry tomatoes to beefsteak varieties that are about the size of a tennis ball. There are many different coloured tomatoes available that make for a vibrant salad bowl.

Tomatoes usually germinate easily and grow quite quickly which makes them interesting to novices and exciting for young gardeners. They can be grown outdoors in the allotment or garden, in a polytunnel or greenhouse and in pots or grow bags on a patio. Small bush varieties can even be grown in a window box or hanging basket so almost anybody can grow a plant or two somewhere.

There is nothing quite like the flavour of a freshly picked tomato and the scent of a greenhouse full of tomato plants is one of the joys of summer.

A few tips on growing tomatoes

There are two main types of tomato plant, these are known as cordon (sometimes called indeterminate) and bush. Cordons have an upright habit rather like a small tree and need to be supported by a stake or cane. Bush varieties are shorter and wider and more shrub like in shape and only need support when heavy with fruit. Cordons need to have their side shoots cut off so that more of their energy goes into the fruit than the foliage. Bush varieties don’t need this.

Tomatoes can be grown outside on the allotment or vegetable garden but benefit from the warmer temperatures in a greenhouse or polytunnel. Growing under cover also helps to protect from blight. Choose blight-resistant varieties if growing outside.

Tomatoes need light and warmth. With insufficient warmth seeds are unlikely to germinate. With insufficient light seedlings will quickly grow tall, thin and weak (known as ‘leggy’) and may collapse and die. Seed packs will often recommend sowing from February but I recommend waiting until March.

Sow tomato seeds

Sow tomato seeds from March until early April.

Sow three or four seeds in a small pot of good quality seed or general purpose compost. A minimum temperature of about 18C is required for germination so place in a heated propagator. If a propagator is not available cover the pot with a plastic bag sealed with an elastic band and place on a warm, sunny window sill. Tomatoes often germinate within a few days but may take up to two weeks. Once germinated remove from the propagator or plastic bag and keep in a warm, sunny place. Keep the compost moist.

When the seedlings are big enough to handle they will need to be potted on. Using a dibber (a plant label or pencil will do) to loosen them, carefully easy the plants out of the compost and repot into small individual pots. Hold the plants by a leaf as the stems are easily damaged. Continue to keep in a warm, light place.

Grow tomatoes

Move tomato plants on to larger pots as they outgrow the ones they are in. Simply ease the plant and the compost out of the pot and replant it in a larger pot with its root ball and the compost. You can plant tomatoes deeply when you repot them. This gives them extra support and they will grow more roots from the stems which helps the plant take up more nutrients and water.

Cordon varieties will need support as they grow. Push a small cane into the compost and tie the stem loosely to it. Be careful not to damage the stem.

Tomato plants can be moved to their final growing positions in May after the risk of frost has passed. They need the temperature to be consistently above 12C for best results so it’s worth keeping an eye on the weather forecast before deciding when to plant out. A polytunnel or greenhouse is ideal but tomatoes can be grown successfully outdoors. Again plant them deeply. I usually remove the lowest leaf or two and plant down to where they were removed from. This not only adds stability and gives them more new roots but also means that your first truss of fruit will be lower on the plant giving you a bit of extra room if you are growing in a greenhouse or polytunnel. Cordon varieties will continue to need support.

If you are growing in pots use large ones, 25cm is about the minimum.

Continue to water regularly, not allowing the compost to dry out. Feed with a proprietary tomato feed once a week throughout the season beginning from when the first flowers appear. Feed in accordance with the pack instructions.

Cordon tomato plants will need to have their side-shoots removed. These grow from the point where the leaves meet the stem. Removing them allows more energy to go into producing fruit and less into growing foliage. Fruit grows on flowering trusses. These grow from the stem mid-way between leaves - be careful not to cut these off when removing side-shoots!

Cut out the growing tip of cordon tomatoes when they reach the top of your greenhouse. It is best to limit indoor tomatoes to a maximum of six trusses of fruit. This gives the best chance of them all ripening. Limit outdoor plants to four trusses as the lower temperatures mean they will ripen less fruit.

Tomato flowers are pollinated by insects so when growing in a greenhouse or polytunnel it is important to open the doors and ventilators regularly.

Harvest tomatoes

Tomatoes usually start to ripen from July and can often continue to produce ripe fruit until October. Pick them as they ripen and enjoy them as fresh as possible. The flavour is at its best when the fruit is at room temperature.

Tomato problems

Tomato blight can be a problem particularly if the weather is warm and humid. It causes the foliage and then the fruit to rot very quickly. As an airborne fungal disease it is most likely to affect plants grown outdoors. Select blight resistant varieties to reduce the risk.

Blossom end rot appears as a scab-like area on the bottom of the fruit. It is caused by lack of nutrients and irregular watering. Keep your plants well watered and use a good quality feed in accordance with the pack instructions to avoid this problem.