Courgettes are easy to grow from seed. They are best started off indoors in pots, but you can also sow them outdoors in the spot where they are to grow.
For earlier crops or in cold regions, sow seeds indoors from mid- to late April at 18–21°C (65–70°F). Sow seeds individually on their side, 1.5cm (½in) deep, in 7.5cm (3in) pots of compost.
In late May or early June, prepare your sowing site by digging in lots of home-made compost or well-rotted manure, to about the depth and width of a spade’s blade. Then sow two or three seeds in the centre, 2.5cm (1in) deep. Cover with a cloche, jar or plastic, and leave the covering in place for two weeks, or as long as possible, after germination. If more than one seed germinates, remove the smaller, weaker seedlings to leave just the strongest one.
You can also buy young plants from garden centres in spring. Plant out in late May to early June, after all risk of frost has passed.
Indoor-raised plants must be hardened off (acclimatised to outdoor conditions) before planting outside in June. Do this by moving young plants into a coldframe for a week. If you don’t have a coldframe, move them outdoors during the day, then bring them in at night for a week. Then the following week, leave them out in a sheltered spot all day and night.
Courgettes need a sunny spot and rich soil, so prepare the planting site for indoor-raised plants as follows:
Make a hole about a spade’s depth and width
Fill the hole with a mixture of home-made compost or well-rotted manure and soil
Sprinkle a general fertiliser over the soil
Then plant one courgette in the centre. If you’re growing several, space them 90cm (3ft) apart.
You can also grow courgettes in growing bags or large containers (at least 45cm/18in wide). Plant one or two per bag or one per container.
Courgettes are thirsty plants and need regular and generous watering as they grow. When you water, try not to splash the leaves. A useful tip is to sink a 15cm (6in) pot into the ground alongside your plant. Then water into the pot, so the water goes right down to the roots and doesn’t sit around the neck of the plant, which can lead to rotting.
Feed every 10–14 days with a high potash liquid fertiliser, once the first fruits start to swell.
Keep the soil moist and grow in cooler locations.
More info on Powdery Mildew
No fruit, or fruit rotting when very small
This is a physiological problem, caused by the growing conditions, not a pest or disease. It is a problem when the weather in early summer is cool and this causes inadequate pollination.
This is usually a temporary problem and once the weather starts to improve, so will pollination. You can try to hand-pollinate plants yourself by removing a male flower (no swelling at their base) and brushing the central parts against the centre of a female flower (female flowers have a swelling at the base – this is the beginning of the fruit). But this is a bit of a hassle, and normally the plant will correct this problem itself.
More info on No fruit, or fruit rotting when very small
Remove damaged plant parts before they can become infected. Cut out infected areas into healthy tissue and clear up infected debris. In greenhouses, reduce humidity by ventilating and avoid overcrowding of young plants and seedlings.
More info on Grey mould
Pick courgettes when they are 10–12.5cm (4–5in) long.
Regular harvesting, when the fruits are small, will ensure a long cropping period.
Greg Wallace tempts us with his grilled vegetable terrine.
'Defender' AGM:Very populer variety, when well grown can yield almost twice that of other varieties. Open habit, solid mid-green fruits, crops over a long season if picked regularly. Excellent resistance to cucumber mosaic virus (CMV).
'El Greco' AGM:Plants have an open growth habit, making picking easy of this prolific cropper.
'Orelia' AGM:Vivid yellow fruit, heavy cropper with open habit. Virtually spine free for ease of picking. Excellent mildew resistance late in the season.
'Tuscany' AGM:Yields large, straight, dark green fruits, held on erect spineless plant. Well suited to cooler UK climate, grows well in the North or on exposed sites.
'Venus' AGM:A compact courgette producing a large crop over a long season, with smooth, spine-free stems.