Tomatoes

Many varieties work well — pick by purpose: fresh eating, sauce, and so on. My ratings for the ones I've actually grown are in the table below.

Sow on the surface and cover lightly with soil. Keep it moist and warm until germination.

Water regularly and feed through the season. Tomatoes want lots of sun and warmth.

Pick when the fruits are fully coloured but still firm. They keep for several days somewhere cool — or turn them into sauce and preserves.

March: sow indoors, 1–2 cm deep in rich soil, kept moist and warm (20–22 °C).
April: late sowings still work early in the month. Start acclimatising plants: a few hours outside on sunny days.
May: plant out for good once frost risk is over. Water the soil, not the leaves. Feed with something potassium-rich.
June: tie the plants to stakes or a trellis and pinch out side shoots, so the plant spends its energy on fruit.
July–August: keep watering, keep an eye out for pests, and start picking as the fruits colour up.
September: keep harvesting as long as they ripen; ease off the watering as the season winds down.
October: pick everything left before the frost takes it. Clear the plants away, and write down what worked and what didn't — next season starts now.