Tomato
Solanum lycopersicum · love apple
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🖨 Printable care card (PDF)At a Glance
| Botanical name | Solanum lycopersicum |
|---|---|
| Common name(s) | tomato, love apple |
| Family | nightshade |
| Plant type | annual (vulnerable to frost, though sometimes living longer in greenhouses) |
| Height × Spread | 1.5–2.5 m × 50–100 cm |
| Position | Full sun |
| Soil | — |
| Flowering | June–August |
| Toxicity | No specific toxicity is listed by the RHS. This is not a guarantee of safety — check with a vet or the ASPCA before pets or children eat any plant. |
| Native range | western South America |
The tomato is a short-lived perennial from the Solanaceae family, widely cultivated as an annual across the United Kingdom for its edible berries. It originates in western South America and was introduced to Europe following the Columbian exchange, reaching British cultivation in the sixteenth century. Modern breeding has produced thousands of cultivars suited to greenhouse production, outdoor growing, and container cultivation. In UK gardens tomatoes are among the most commonly grown fruit crops, with sowings typically made from late winter under glass for heated propagation.
Quick-Care Table
Overview
Tomatoes require warmth, regular moisture, and steady nutrition to crop well in the British climate. Outdoor cultivation is reliable only in milder regions and in summers of average or better warmth; in cooler areas, or for an earlier harvest, plants are grown under glass, in polytunnels, or on sheltered patios. Fruit quality differs markedly by cultivar: cherry types tend to ripen reliably outdoors, while large beefsteak fruits usually require the consistent temperatures of a greenhouse to develop full flavour and size. UK growers should expect to start plants under cover in spring, transplant once frost risk has passed, and provide support for taller types.
RHS hardiness is consistently reported as tender (H1c), with damage occurring below 5 °C and death from frost. Some sources refer to an H2 rating for very short cold tolerance, but the most commonly cited RHS classification places tomato at H1c. Unheated greenhouse cultivation extends the season considerably compared with outdoor growing.
Appearance
The tomato plant has a sprawling or upright habit depending on type. Indeterminate (cordon) cultivars produce a single leading stem that continues to grow throughout the season, reaching 2 metres or more when supported. Determinate (bush) cultivars are compact, typically 30–60 cm tall, with stems that terminate in flower trusses. Compound, deeply lobed leaves carry a characteristic pungent scent when bruised and may be sparsely hairy.
Flowers are yellow, five-petalled, and borne in clusters (trusses) that develop into fruit. Individual flowers are self-pollinating, though vibration from wind or bees improves fruit set. Fruits are botanically berries, varying from 1 cm cherry forms to 15 cm or more in beefsteak cultivars. Skin colour at maturity is most commonly red, but yellow, orange, pink, green-when-ripe, purple, and striped cultivars are widely available in the UK. Shape ranges from round and oblate to elongated plum and oxheart forms.
Growing Conditions
Tomatoes need a warm, sheltered position in full sun. Soil should be fertile, moisture-retentive, and free-draining; a pH of 6.0–6.8 is ideal. In containers, a peat-free multipurpose compost or a loam-based mix such as John Innes No. 2 suits most cultivars, though the largest-fruited types benefit from the additional fertility of John Innes No. 3.
Outdoor plants benefit from a south- or west-facing wall, fence, or open ground with shelter from cold winds. Greenhouses and polytunnels provide the most reliable cropping in the UK, particularly in the north and at higher elevations. Ventilation matters: closed, stagnant environments reduce pollination and encourage disease. Daytime temperatures of 18–24 °C with night temperatures above 12 °C are broadly optimal; temperatures above 27 °C or below 10 °C reduce fruit set.
Planting and Care
Sowing is carried out from late January to early April in a heated propagator at 18–21 °C, with seedlings pricked out into individual pots once the first true leaves have formed. Plants are gradually hardened off before being transplanted to their final position once frost risk has passed, typically late May to early June in most of the UK and a week or two later in colder areas and at altitude.
Watering should be consistent: irregular supply leads to blossom end rot and fruit splitting. Outdoor plants in summer may need 5–10 litres per plant per week, more in greenhouses or during hot spells. Water at the base of the plant rather than over the foliage to limit foliar disease. Mulching with straw, composted bark, or black plastic helps conserve moisture and suppress weed growth.
Feeding begins once the first truss has set. A high-potash liquid fertiliser (such as one formulated for tomatoes) is applied weekly, with the frequency reduced during very hot weather or for container plants that are flushed through with daily watering. Excessive nitrogen produces leafy plants at the expense of fruit.
Pruning is mainly relevant to cordon types. Side shoots that develop in the leaf axils are removed when small, and the leading shoot is stopped one truss above the topmost desired truss (often four to six trusses outdoors, up to eight or more under glass). Bush cultivars require minimal pruning apart from the removal of dead or yellowing foliage.
Propagation is by seed for most cultivars. F1 hybrids do not come true from saved seed; heritage or open-pollinated types can be saved, though cross-pollination between cultivars is common, so isolation is needed to maintain a named strain. Semi-ripe cuttings root readily in water or moist compost and can be used to overwinter a favourite variety on a windowsill, though fruit from overwintered plants is generally smaller.
Seasonal care runs as follows in the UK. January–March: sow seed under heat. April: prick out and pot on. May: harden off and prepare outdoor beds. June: transplant outdoors; train cordons up canes or string. July–August: water, feed, and pinch out side shoots. September: remove lower leaves to improve airflow and aid ripening of late trusses. October: harvest remaining green fruit for indoor ripening or chutney. November–December: clear spent plants, compost only disease-free material, and clean greenhouse glass and structures.
Common Problems
Blight (Phytophthora infestans) is the most damaging disease of outdoor tomatoes in the UK, particularly in warm, wet summers. Brown-black lesions on leaves and stems, and greasy brown patches on fruit, signal infection. There is no cure; affected plants should be removed and destroyed (not composted). Resistant cultivars are available, including 'Crimson Crush' and 'Mountain Magic'.
Tomato leaf mould (Passalora fulva, formerly Fulvia fulva) is a greenhouse problem, producing yellow patches on upper leaf surfaces and olive-brown mould beneath. Improve ventilation and remove affected leaves.
Blossom end rot causes a sunken, dark patch at the base of the fruit. It is a physiological disorder linked to inconsistent watering and calcium transport, not a pathogen, and is addressed by even watering and mulching.
Splitting occurs when a dry period is followed by heavy rain or watering, causing the fruit to swell faster than the skin can stretch. Steady moisture prevents it.
Whitefly, aphids, and red spider mite are common pests under glass. Biological controls (Encarsia formosa for whitefly, Phytoseiulus persimilis for spider mite) are widely used in the UK and are available from several biological-control suppliers; confidence in current UK availability is high.
Toxicity: the foliage and unripe green fruit of tomato plants contain solanine and other glycoalkaloids, and are considered mildly toxic if eaten in quantity. Ripe fruit is widely consumed. Standard horticultural hygiene is sufficient to keep pets and children safe, though plants should be located out of reach of grazing animals.
Popular Varieties
The following cultivars are well established in UK seed catalogues and at major UK retailers. Several bear the RHS Award of Garden Merit (AGM), indicating they have performed well in RHS trials.
- 'Gardener's Delight' — AGM. A cherry-type cordon producing heavy crops of small, sweet red fruits. Reliable outdoors and a longstanding favourite among UK growers.
- 'Sungold' — An orange cherry cordon with a notably sweet flavour. Performs well under glass and in a sunny outdoor spot.
- 'Moneymaker' — A traditional, widely grown round red tomato suited to indoor and outdoor production. Bred in the twentieth century and a familiar name in UK seed catalogues.
- 'San Marzano' — A plum-type Italian heritage variety popular for cooking and sauce-making. Usually grown under glass in the UK for reliable ripening.
- 'Tigerella' — AGM. A red-and-yellow striped round tomato with an early cropping habit that makes it well suited to outdoor growing in the UK.
- 'Roma' — A determinate plum cultivar commonly used for paste and sauce, suitable for outdoor container growing.
Other UK-available cultivars include 'Ailsa Craig', 'Alicante', 'Shirley', and 'Sweet Million'; the list above is representative rather than exhaustive. Cultivar names change frequently in trade, and growers should check current seed catalogues (such as those from Suttons, Marshalls, Kings Seeds, and Thompson & Morgan) for the latest available types.
Cultivars and Varieties
| Cultivar | Height | Flower | Notes | AGM |
|---|---|---|---|---|
| 'Acme' | — | — | said to be in the parentage of most cultivars for the next twenty-five years, introduced in 1875 | |
| 'Paragon' | — | — | introduced in 1870 |
Pests and Diseases
| Problem | Symptoms | Management |
|---|---|---|
| Tomato blight | Dark brown patches on leaves and stems, often with white fungal growth, leading to rapid collapse. | Improve air circulation, avoid wetting foliage, and remove infected plant parts immediately. |
| Glasshouse whitefly | Tiny white flies swarm when disturbed; sticky honeydew on leaves promotes black sooty mould. | Use yellow sticky traps for monitoring and control populations with biological agents or approved insecticides. |
| Blossom end rot | The base of the fruit turns dark brown, sunken, and leathery due to calcium deficiency. | Water regularly to maintain even soil moisture and ensure adequate calcium in the growing medium. |
| Tomato leaf mould | Yellowing leaves with a fuzzy, olive-green or greyish fungal growth on the undersides. | Ensure good ventilation, avoid overcrowding, and remove severely affected leaves to reduce humidity. |
| Magnesium deficiency | Older leaves develop yellowing between the veins while the veins remain green. | Apply a high-potassium tomato feed containing magnesium or use Epsom salts solution. |
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