Sow

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.

Sow indoors

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, 13mm (½in) deep, in 7.5cm (3in) pots of compost.

Sow outdoors

Sow two or three seeds 2.5cm (1in) deep outdoors in late May or early June and cover with cloches, jars or plastic; leave this in place for two weeks, or as long as possible, after germination. Thin the seedlings to leave the strongest one.

You can also buy young plants from garden centres in spring. Plant out in late May - early June after risk of frost has passed.

Grow

Two weeks before planting or sowing seed outdoors, make planting pockets 90cm (3ft) apart for courgettes, 90cm (3ft) for bush plants of summer squashes and 1.5m (5ft) for trailing plants of summer squashes. Do this by making a hole about a spade’s depth and width and fill it with a mixture of compost or well-rotted manure and soil. Sprinkle a general fertiliser over the soil. Plant one plant in each planting pocket.

For indoor-raised plants, harden off (acclimatise) before planting. Do this by moving young plants into a coldframe for a week. If you don’t have a coldframe, move plants outdoors during the day, then bring in at night for a week, then the following week, leave them out in a sheltered spot all day and night.
Plant outside on top of your planting pocket in early June.

You can also grow courgettes, marrows and summer squashes in growing bags or containers (at least 45cm/18in wide). Plant one or two per growbag, or one per container. These will need regular watering as they mature.

Courgettes are thirsty plants. When you water, try not to get water on the leaves. One tip is to sink a 15cm (6in) pot alongside the plants when planting out. If you water into the pot, it will help ensure that 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.

Common problems

Powdery Mildew: Appears as a white powdery deposit over the leaf surface and leaves become stunted and shrivel.

Remedy: 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.

Remedy: 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

Grey mould: A usually grey, fuzzy fungal growth which can begin as pale or discoloured patches. Grey mould ( botrytis) is a common disease especially in damp or humid conditions. Spores enter plants via damaged tissue, wounds or open flowers. Mould can also damage ripening fruit such as strawberries. Black resting spores survive over winter.

Remedy: 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

Harvesting

Harvest courgettes when 10-12.5cm (4-5in) long.

Regularly picking courgettes while they are small will ensure a long cropping period.

Recipes

Greg Wallace tempts us with his Grilled vegetable terrine.

Varieties

‘Venus’ AGM:A compact courgette producing a large crop over a long season, with smooth, spine-free stems.

‘Supremo’ AGM:Its compact growing habit makes this courgette ideal for areas with restricted room.

‘El Greco’ AGM:Plants have an open growth habit, making picking easy of this prolific cropper.

‘Tiger Cross’ AGM:This is a marrow variety, producing large striped fruits, good for winter storage.

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