How to grow Courgettes

Courgettes are now a common, summer staple in the vegetable garden. They are relatively easy to grow and they can be added to salads and eaten raw, or lightly steamed or roasted. Courgettes and marrows are actually the same thing – leave a courgette to mature on the plant and it will become a marrow! However, many courgette varieties have been bred to produce a lot of small, tasty fruit.

Courgette varieties

There are numerous excellent courgette varieties including those producing round or yellow fruit: Defender, Eight Ball (round), Gold Rush (yellow), One Ball (round and yellow), Parador, Sunburst (yellow), Tondo di Chiario Nizza, Zucchini.

What you’ll need to start growing courgettes

You don’t need much equipment to grow courgettes. Here are the basics:

Garden fork and spade
Trowel
Well-rotted farmyard manure
General purpose fertiliser
High potassium fertiliser
Courgette seeds

For indoor sowing:

9cm (3.5in) pots
Seed sowing compost
Propagator (optional)

For outdoor sowing:

Cloches, jam jars or horticultural fleece

How to grow courgettes:

Cultivation

Courgettes prefer a sheltered position in full sun and a fertile soil that holds plenty of moisture. They are reasonably large plants, so need plenty of room, spacing them up to 90cm (3ft) apart. Some more compact varieties are also available - and these are also best suited for growing in containers.

For best results, they can be grown in planting pockets. Roughly 2 to 3 weeks before sowing seed or planting out, dig a hole 30cm (12in) square and deep and fill with a mixture of compost or well-rotted manure and soil. Leave a low mound at the top and sprinkle a general feed over the soil.

As courgettes need plenty of water, sink a 15cm (6in) pot alongside them when planting out. Watering into the pot ensures the water goes down to the roots and doesn't sit around the neck of the plant, which can lead to rotting. It also keeps it off the foliage, which helps reduce problems with powdery mildew.

Sowing courgettes

For the best results, sow the seeds indoors from mid to late April 13mm (1/2in) deep individually in 7.5-9cm (3-31/2in) pots of seed sowing compost. Place the pots in a propagator or other warm place at 18-21°C (65-70°F). Harden off the young plants for 7-10 days before planting outside in late May/early June after the fear of frosts has passed.

Outside, sow 2 or 3 seeds 2.5cm (1in) deep in the planting pocket in late May or early June and cover with a cloche or jam jar. Thin the young seedlings to leave just the strongest one.

How to care for courgettes

As the young plants are susceptible to frost and cold weather, cover them with fleece or a cloche if the weather turns cold.

Keep the soil constantly moist by watering the soil around the plants - not over them - whenever needed. Once the first fruit starts to swell, feed every 10-14 days with a high potassium feed.

Harvesting courgettes

Harvest courgettes when they are 10-12.5cm (4-5in) long. Regular picking when they are small ensures a long cropping period over several months

They produce large crops, so one or two plants is all that's needed to feed a large family.

Courgettes may be susceptible to the following problems: lack of fruit set, young fruit rotting.

Common pests, disease and problems of courgette plants

Powdery mildew	Powdery mildew on courgettes is a common problem. This is a fungal disease that appears as a white powdery deposit on the leaves, stunting growth and causing leaves to shrivel. Drought-stressed plants are more susceptible. Dig organic material into the soil before planting to improve soil water retention. Space plants when planting to ensure good air circulation. Remove any affected growth promptly. Water regularly in dry periods.
Yellow courgette leaves	Older courgette leaves often turn yellow and drop off the plant. This is not a cause for concern as they will be replaced by new growth, but also see Cucumber mosaic virus.
Cucumber mosaic virus	Courgette leaves turning yellow can also be due to cucumber mosaic virus. This causes deformed, stunted leaves with a characteristic ‘mosaic’ yellow patterning. Affected plants produce few or no flowers, and any fruit that develop are small and inedible. Remove and destroy affected plants promptly. Wash hands and tools after handling affected plants. Plant disease-resistant varieties. No chemical controls are available.
Grey mould / Bortrytis mould	Grey mould is a fungal disease that appears as powdery grey mould at the stalk of courgette, gradually covering the whole fruit, which then rots. Remove any dead leaves or flowers. Remove any affected fruit promptly. Space plants well when planting to allow good air circulation. There are no chemical controls available for grey mould.
Courgettes rotting when small or not setting	Courgette fruits can appear to start swelling but then rot or drop off the plant while still small. This occurs when the flowers are not pollinated, and is usually more of a problem early in the season. If the problem persists, hand-pollinate flowers using a small paintbrush.
Slugs and snails	Slugs and snails will eat the leaves of young courgette plants, and can be identified by the slime trails that they leave, as well as the damage they do. Check plants at night and remove slugs and snails by hand. Covering the soil around plants with crushed eggshells or grit may have some effect. Scatter environmentally-friendly slug pellets if other methods are not sufficient.