Tomatoes were late to arrive on our shores. It’s only been a couple of centuries since we were willing to eat them, yet now it’s hard to imagine the British diet without them. Flick open a seed catalogue and the tomato pages blaze like a sweetshop window, detailing hundreds of fruit in different colours, shapes and sizes. It’s no wonder gardeners are obsessed!
The good news is they’re easy to grow, whether it’s in a hanging basket, balcony pot, greenhouse or even in the flower border.
Depending on how they grow, tomatoes are either bush (determinate) or cordon (indeterminate). Bush tomatoes don’t need training and pinching out and they’re ideal for pots, hanging baskets or even window boxes. They’re quicker cropping than cordon types, but shorter in their overall season with a smaller yield too.
It’s best to train cordon tomatoes up a support and remove any sideshoots. These are your archetypal greenhouse plants but there’s no reason why you can’t grow them in a patio pot.
They crop over a longer season and have a tall narrow stature that requires a support.
Seed catalogues may group them by fruit type too. Beefsteaks are the body builders of the tomato world, beautiful sliced with mozzarella; plum tomatoes are useful cooking tomatoes with fewer seeds and a meaty flesh to make beautiful sauces; cherry toms are sweet little flavour bombs. The raft of ‘medium-sized’ cultivars are the kitchen workhorses, excellent in most dishes. All differ in their combination of fragrance, sweetness and acidity, which is half the allure of growing your own.
Sowing and pricking out
Tomatoes need warmth to thrive. If you intend to grow tomatoes outdoors, wait until late March or early April to sow. Those destined for a greenhouse can be sown in late February-early March. In both cases, find a warm sunny windowsill or heated greenhouse bench to grow them on until cold weather has passed.
Between germination and planting, keep young plants growing as smoothly as possible. Keep temperatures above 15C (60F), and certainly not below 10C (50F). Frost is lethal.
Each time their roots fill a container, pot on the tomato, planting deeply. New roots grow from the buried stem encouraging a strong, stocky plant.
Greenhouse tomatoes are usually planted into their final position in late April to early May, while outdoor tomatoes need careful acclimatising and extra protection from fleece on cool nights before they go outside in late May to early June.
Tomatoes like full sun and a moist, fertile but well-drained soil. Improve borders with well-rotted organic matter, or if you’re growing in containers choose one that’s at least 30cm (12in) diameter and use a specialist peat-free tomato compost. Those that require no extra feed are well worth the extra money. Otherwise, you’ll need to start weekly feeds of high potash tomato fertiliser once the first fruit has set.
Training the plant
Bush tomatoes don’t need specific training, but you may find a single stake and a corset of twine helps hold large bush cultivars together. If growing more than one, space them about 45cm (18in) apart.
Cordon tomatoes do need a bit more care. Stake them for support and regularly tie in. In a greenhouse you can twist them around a length of twine tied to the ceiling struts. Sideshoots appear on a diagonal between the main stem and a leaf. Snap these off while they’re small to focus the plant’s energy on developing fruit trusses. If it’s early in the season you can conjure a few extra plants by popping these sideshoots into a pot of damp compost to root.
Gradually remove leaves from below the bottom fruit truss, plus any leaves that shade your fruit. Water the soil at the base of the plant to avoid wetting the foliage and clear away leaves or fruit showing damage or signs of mould.
Eventually, falling temperatures and reduced sunshine spell the end of the year’s harvest. To encourage fruit to ripen, pinch out the tip of outdoor tomatoes once they’ve set four fruit trusses – or six or seven for indoor tomatoes – so all the plant’s energy is directed towards the developing fruit.
HOW TO SOW THEM
- Fill a small pot with compost and sow seed thinly across the surface. Sprinkle lightly with compost, label and water with a fine hose. Keep them warm
- Place on a heated mat, inside a windowsill propagator or in an airing cupboard (check daily for signs of germination). You’re after 20-25C (68-77F).
- Grow them on Keep them warm and bright, rotating windowsill pots daily. Prick out into individual pots once they have their first true leaves.
TROUBLESHOOTER
Q. Why are my fruit splitting?
A Dry soil followed by a sudden deluge can cause fruit to swell rapidly and split. This is harder to control outside, but having a healthy soil with plenty of organic matter helps. Mulch around plants with compost to retain moisture during dry spells. Indoors, try installing a drip irrigation system on a timer to keep things growing smoothly.
Q. How can I protect plants from blight?
A Late blight is a fungal-like organism (Phytophthora infestans) that attacks both tomatoes and potatoes, causing browning of foliage, stems and fruit. It’s dispersed on the wind, so greenhouse plants tend to escape the worst of it, but those grown outside are more vulnerable. It’s favoured by damp conditions, which is why wet summers coincide with the worst blight years. Put infected foliage in green bins for high-temperature council composting. Blight-resistant ‘Crimson Crush’, ‘Mountain Magic’ or beefsteak ‘Oh Happy Day’ are all well worth growing outdoors.
Q. What are the dark patches at the base of fruit?
A. These are a sign of blossom end rot, caused by calcium deficiency. Uneven watering is often the cause and it is fairly common in greenhouse tomatoes. Remove these fruits once you see them or they may start to rot on the plant.
Q. Why are flowers failing to set fruit?
A Very low or very high temperatures can cause flowers to drop rather than form fruit. Don’t plant them out too early, and try to keep greenhouse temperatures as steady as possible. Pollination is usually carried out by insects and wind; you can mimic this by brushing the stamens with a paintbrush or gently shaking stems.