Home-grown tomatoes are worth the effort because you can choose varieties for flavour instead of shelf life. A sunny patio can support a surprisingly productive cherry tomato, while a greenhouse allows you to experiment with larger-fruited types. The secret is understanding whether you have a bush or cordon tomato, then matching its support, pruning and watering to that habit.
Pick a tomato variety for your space
Cordon, or indeterminate, tomatoes keep extending their main stems and need tall supports. They suit a greenhouse, sunny wall or other position where a cane or string can be installed securely. Bush tomatoes are naturally shorter and produce more branching stems; some compact or trailing varieties are designed for pots and hanging baskets.
Beginners often do well with small-fruited varieties because they tend to ripen more readily in a short British summer. Read the seed packet for plant height, resistance to disease and whether it needs a greenhouse. Don't assume a large beefsteak variety will grow happily on a shaded balcony.
When to sow tomato seeds in the UK
Tomatoes need warmth to germinate and plenty of light once the seedlings emerge. Most gardeners sow indoors in late winter or spring, adjusting the timing according to whether plants will grow in a greenhouse or outdoors. Starting too early without adequate light produces leggy seedlings that struggle later.
Fill small pots or seed modules with peat-free seed compost and sow at the depth recommended on the packet. Keep the compost gently moist in a warm place. Once the shoots appear, move them promptly into bright light; a windowsill that feels warm may still be too dark in February.
When seedlings develop true leaves, transfer them carefully into individual pots. Handle a seedling by a leaf rather than crushing its fragile stem. Pot on again if roots fill the container before outdoor planting conditions are suitable.
When can tomatoes go outside?
Tomatoes are tender plants and can be damaged by frost or cold nights. Harden off young plants gradually before moving them outdoors, exposing them to sheltered daytime conditions first. Wait until the danger of frost has passed and nights are reliably mild.
In much of northern England, outdoor planting may be later than in sheltered southern gardens. A greenhouse gives more protection but still needs ventilation and care during unexpectedly cold spells. Do not rush because a date on a calendar says summer has arrived.
Choose the warmest, sunniest sheltered position available. Tomatoes can survive in weaker light, but fruit development and ripening suffer. Soil or compost should drain well while retaining sufficient moisture for a heavy-feeding crop.
Planting tomatoes in pots or growing bags
Use a generously sized container with drainage holes and fresh peat-free compost. Larger varieties need more root room than tiny patio tomatoes. Set the plant carefully into the compost, firm around its roots and water thoroughly.
Install the support for a cordon tomato at planting time rather than driving a cane through its mature root system. A tall bamboo cane or well-anchored greenhouse string can work, provided the plant is tied in gently as it grows.
Growing bags are convenient, but they can dry out quickly in hot weather. Check moisture rather than treating every bag as though it holds enough water for days. Plants crammed together may shade one another and trap damp air around foliage.
The difference between pruning cordon and bush tomatoes
This is the most important tomato-care distinction. Cordon tomatoes are generally trained as one main stem. Remove the small sideshoots growing from the joints where leaf stalks meet that stem. Check regularly because a missed sideshoot can become a substantial branch.
Bush tomatoes usually keep their sideshoots. Removing them indiscriminately may reduce the crop. Some bush varieties need short supports when loaded with fruit, but they do not receive the same routine training as a cordon.
Never prune solely because you saw a method used online. Identify your variety first. The RHS advises managing cordon height by stopping the growing tip after the appropriate number of fruit trusses have formed, with different recommendations for greenhouse and outdoor crops.
How often should tomato plants be watered?
Tomatoes appreciate consistent moisture. Allowing compost to become bone-dry, then flooding it, can stress the plant and contribute to problems such as blossom-end rot. Containers may need daily checking during summer, especially in windy conditions.
Feel the compost below the surface, then water at the base when necessary. Avoid repeatedly splashing foliage, particularly inside a poorly ventilated greenhouse. Too much water can be harmful as well: roots need oxygen and cannot function properly in saturated compost.
A mulch on garden-grown plants can help keep moisture steadier. In growing bags, water slowly enough to reach the root area instead of running straight off the compost's dry surface.
Feeding tomatoes when flowers appear
A tomato plant making flowers and fruit uses nutrients steadily. Plants in containers often benefit from a liquid feed designed for tomatoes once the first fruit truss has set, applied according to the label. Garden plants in fertile soil may have different needs.
Don't increase the dose to compensate for weak light or a struggling root system. Too much feeding can cause salt build-up in containers. If leaves yellow or curl, investigate moisture, temperature and pests as well as nutrition.
Flowers, pollination and developing fruit
Tomato flowers are normally self-fertile. Wind and movement help pollen transfer, and visiting insects may also assist. In a greenhouse, gentle movement of flowering trusses can help; ensure good airflow without exposing plants to extremes.
Very hot or cold conditions can interfere with fruit set. Flowers that drop without forming tomatoes are not necessarily a sign of disease. Review greenhouse temperature, ventilation and watering before adding fertiliser.
Once fruit develops, keep tying in vigorous stems. Heavy trusses can pull a plant sideways, particularly after watering or during gusty weather.
Harvesting ripe tomatoes
Pick fruits when they have developed their mature colour and feel appropriately ripe for the variety. Tomatoes may be red, yellow, orange or dark purple, so colour alone needs context. Gently twist or snip them free without tearing the stem.
At the end of summer, some fruits may remain green as temperatures fall. You can bring mature green fruit indoors to ripen, although very immature fruit may not develop properly. Put them somewhere suitable at room temperature and check regularly for spoilage.
Never eat tomato leaves or stems; the ripe fruits are the usual edible harvest.
Common tomato problems
Blossom-end rot: A dark, sunken patch develops at the base of fruit. Uneven water supply can interfere with calcium uptake. Maintain steadier moisture; simply adding calcium is not always the answer.
Blight: Dark, spreading lesions on leaves and stems, sometimes accompanied by affected fruit, can indicate this serious disease in damp conditions. Remove diseased material safely and follow current local advice.
Leaves curling: Heat, irregular watering or other stresses may be responsible. Look at the whole plant before assuming infection.
Few ripe tomatoes: Consider variety, growing season, light levels and whether the plant has become overgrown with sideshoots.
Split fruits: Sudden changes in moisture can contribute. Harvest ready fruit promptly and keep watering more even.
Your first tomato-growing season
Grow one bush cherry tomato in a large patio pot and one cordon if you have room and a tall support. You'll quickly see how different their habits are. Give them light, consistent moisture, appropriate feeding and protection from cold.
The plants tell you a great deal if you check them regularly. Healthy foliage, steady flower production and fruit ripening are better measures of progress than a rigid calendar.
Source
Royal Horticultural Society: How to Grow Tomatoes.