Tomato

Light and exposure

The tomato demands the maximum of sun and warmth. Choose the most sheltered and sunniest spot in the garden, ideally against a south-facing wall that releases its heat in the evening. It needs at least six to eight hours of direct sun a day.

In our climate, growing in a greenhouse, under a tunnel or even under a simple lean-to that protects the foliage from rain changes everything: it brings the harvest forward, extends it into autumn and sharply reduces the risk of blight.

Watering

Water regularly and always at the base, never on the foliage. Wet foliage is the first way in for blight during our humid summers. Morning is the best moment, so the soil warms up and everything dries during the day.

Aim for consistency rather than abundance. Swings between drought and heavy watering split the skin of the fruits and cause blossom end rot, that black patch at the bottom of the tomato. A mulch at the base keeps moisture stable and limits soil splashing onto the lower leaves.

Soil and repotting

The tomato is a hungry plant. It likes deep soil, rich in compost and well drained. Work in mature compost or decomposed manure at planting time, and avoid replanting in the same spot two years running so as not to exhaust the soil or keep diseases going.

In a pot or a container on a terrace, allow a large volume, at least thirty litres per plant, with a quality vegetable potting mix and good drainage at the bottom.

Temperature and humidity

The tomato only really gets going above 15 degrees and suffers below 10. It tolerates no frost. Below 12 degrees at night, growth stalls and the flowers set poorly, which gives clusters that drop without forming fruit.

That is the whole Belgian challenge: our nights stay cool late into spring and turn cold again early in autumn. A greenhouse or tunnel gains a few precious degrees and lengthens the harvest window at both ends of the season.

Pruning and upkeep

For indeterminate varieties, the most common ones, stake firmly and remove the suckers, those shoots that start in the axil between the main stem and a branch. This concentrates the energy on the fruit.

At the end of the Belgian summer, around mid-August, top the plants above the last worthwhile cluster. The time left will not be enough to ripen more fruit, so better to feed those already set. Thin out the lower leaves moderately to let air circulate and let the sun reach the clusters.

Pests and diseases

Blight, caused by Phytophthora infestans, is the number one enemy of the tomato in Belgium. Brown, oily patches on the leaves and stems, then on the fruit, can ravage a plant in a few days of mild, damp weather. The best defence is to keep the foliage dry: growing under cover, watering at the base, plants spaced out and well aired.

Also watch out for blossom end rot, tied to irregular watering rather than to a disease, and aphids. Remove and throw away, without composting, any foliage affected by blight to slow the spread.

Propagation

Sowing is done indoors, warm between 20 and 24 degrees, from March onwards. Sow in pots, half a centimetre deep. Germination takes a good week. Prick out the seedlings as soon as they have their first true leaves, burying them a little deeper, because the stem puts out new roots.

Harden off the young plants by taking them out gradually during the day before planting. Only set them outdoors after mid-May, once all risk of frost has passed.

Toxicity

The ripe fruits are edible, but the leaves, stems and green fruit contain solanine and tomatine, toxic in quantity. Do not eat the foliage and keep it away from animals.

Month-by-month care calendar

Green Hub tips

• In our humid climate, a simple rain shelter above the plants is worth all the treatments: blight needs wet foliage to take hold.
• Bury the young plants deeper than they were in their pot. The stem covered with soil makes new roots and gives a sturdier plant.
• Around mid-August, top the plants without hesitation. Fruit set after that date will not have time to ripen before the cold.
• Regular rather than abundant watering: it is the swings that split the skin and blacken the bottom of the tomatoes.