Everything you need to know about growing tomatoes

Nothing beats the smell and flavour of a home-grown tomato and this guide will provide everything you need to grow a great crop whether you have a small space on a patio, a hanging basket or a huge greenhouse.

First, select the right variety for your space. Tomatoes are divided into Vine (also known as indeterminate) and Bush.

Vine types are best suited to greenhouses and polytunnels due to their large size and their care requirements. These tomato plants are grown with a single main stem and the side shoots need to be removed regularly. They can grow to be several meters long and therefore they need to be supported with canes or support frames.

Bush tomato varieties are more compact, tending to stay bushy and quite short, so they are ideal for growing outside as they are very easy to support with a bamboo cane. Popular varieties including Tumbling Tom, Red Alert and Garden Pearl. It is not necessary to remove the side shoots with these varieties.

When to sow tomato seeds

Sowing tomato seeds is best done in a heated propagator or heated greenhouse - sow January to early February. In an unheated propagator or unheated greenhouse - sow late February to early March. Outdoors - sow late March to early April.

1: How to sow tomato seeds
- Fill 8cm pots with compost (any multi-purpose compost) and flatten the compost down lightly.
- Place 3 seeds on the surface of the compost in each pot, space the seeds evenly and sow a few more than you need. Cover the seeds with approx. 0.5 to 1cm of compost.
- Water the compost so that it is damp but not saturated.
- If you have a propagator put the pots in the propagator and put the lid on.
- Put the pots or propagator in a warm place away from direct sunlight. The room needs to be a minimum of 18°C.

2: Care for the seedlings

Day 17 -28: Seedlings should appear but some varieties can take up to 28 days to germinate – see your seed packet for details. Once the seedlings have appeared move the pots/propagator to a bright, warm part of the house, a windowsill is ideal. Keep the compost moist, but not wet. If you are using a propagator lid remove the lid when all seedlings have appeared.

3: Remove the weak seedlings

Day 50 -60: It will be clear which seedlings are strongest and you can pull out the weakest ones, either putting them into other pots, or rejecting them.

4: Transfer to the final pot

- Once the tomato plants are 6 to 8 inches tall plant them into your chosen pot between 6 and 12 inches in diameter (see seed instructions for ideal pot size).

- Fill your pots with multi-purpose compost.

- Make a hole in the compost large enough for your tomato plant.

- Lever the young plant out of the 3inch pot with a pencil or dibber and carefully lower into the new pot.

Surround the plant with compost, firming compost around the plant and add more compost to fill the pot. Water so that the compost is damp but not saturated.

Hardening off and night protection

Young tomato plants need to be gradually weaned off the heat of a propagator, greenhouse or polytunnel. The timing of this stage depends on the temperature conditions and whether you have a heater in your greenhouse or polytunnel.

The weaning off period required depends on the time of sowing rather than the development stage of the plant. This is because the key is not to subject your young plants to night temperatures below 4°C without protection.

Once your plants have developed their true leaves (the leaves that are typical of the mature plant, not the two leaves that first appear) they will usually be ready to be weaned off the heat for a few days. Open the vents, remove the lid and over a few days reduce the temperature until it's off completely. Once the plants have been in the propagator without a lid and no heat for a couple of days you can remove your plants, just keep an eye on the night temperatures.

You will need to provide protection at night until the night-time temperature outside/in your greenhouse/polytunnel is no cooler than about 10°C. A mini greenhouse, cloche, coldframe or tall propagator such as the Vitopod are ideal.

Caring for your tomato plant

When the risk of frost has passed tomato plants can be placed outside, but they will do better if kept in a greenhouse or indoors overnight until daytime temperatures are no lower than 17°C. Do not put tomatoes outdoors until the night temperatures do not drop below 10°C. We’re in Lancashire, so for us that means late April, which would mean sowing in March.

Take care not to let the plant dry out too much or to over-water. Tomatoes hate irregular watering - sporadic watering can cause blossom end rot or cause the fruit to split - little and often is the rule here. Try to avoid watering late in the evening because tomatoes will use very little water during the night. It’s always better to water in the mornings and early afternoon.

Feed your tomatoes with a general liquid fertiliser until they start to develop flowers, then use a high potash fertiliser to encourage your tomatoes to flower and fruit. Keep your tomato plants weed-free and keep an eye out for the common pests.

Side-shooting tomatoes, pinching out and removing leaves

Vine varieties need their side-shoots removing, which means removing the new shoots that grow between the leaf and the stem. This lets your tomato plant put all its energy into growing its main stem until you remove the growing tip. Take care to remove the side shoots cleanly, without leaving any stubs or damage as this will encourage fungal diseases such as botrytis.

Pinch out the growing tip when the plant reaches the desired height. Don’t leave it too late in the year before removing the growing tip as there may not be enough time to let the last tomatoes ripen. Leave 2 leaves above the top flowering truss when removing the growing tip.

You will need to remove the lower leaves, known as deleafing, to encourage the tomatoes to ripen. Use a sharp knife. Remove leaves up to the first (lowest) truss that has ripening tomatoes on.

Harvesting

Your should have ripe tomatoes from mid-May until October.
Harvest tomatoes as and when they ripen to encourage the plant to produce more tomatoes. Always pick the tomato with the calyx (green stalk) still attached to the tomato. There is always a knuckle between the calyx and the truss which allows you to pick the tomato easily. Leaving the calyx on the tomato will keep it fresher for longer.

A ripening cover considerably speeds up ripening, reducing the proportion of tomatoes that will need to be picked green!

When night temperatures are below 4°C bring your young plants into the house overnight.
We find that putting the pots on a tray makes it easy to bring all the plants into the house without too much trouble.

A great resource for tomato guides, feed and planters is http://www.greenhousesensation.co.uk/veg-growing-kits/tomato-growing-kits/