Courgettes, marrows and summer squashes are part of the cucurbits family (Cucurbita pepo), and have similar growing requirements. Courgettes are basically immature marrows, so if you leave a courgette to grow on it will become a marrow. However, special varieties have been developed for each type, so a dedicated courgette variety may actually produce a fairly inferior marrow.
Soil Type: Best in a rich, well drained, loam.
Conditions: Full sun.
Ease of Cultivation: Easy
Type: Fruiting and flowering vegetable.
Hardiness: Not hardy in the UK (protect from frost).
When to Sow: April to May.
Harvest Season: Mid summer to autumn.
Courgettes can fail to set fruit in poor weather, where less pollinating insects are about. However, there are F1 hybrids that can set fruit without pollination.
Provide a rich free-draining soil with a good supply of water. Plant is a sheltered sunny site.
Courgettes are heavy croppers, so just a couple of plants will usually be sufficient to supply the average family.
Sow seeds with the pointed end facing downward, in pots or modules in April under glass or direct at the growing site in May, once all danger of frost as past. Cover outdoor sowings with a cloche or jam jar to encourage germination.
Sow two or three seeds per position and discard the weakest. Start a couple extra plants to ensure a reserve in case of failure.
The seeds have a long life expectancy if stored
in an airtight container and in a cool place. So save
the rest of the packet for the following year.
Space plants at 2ft (60cm) or more apart each way,
depending on variety. Harden
off seedlings grown under glass before planting
Keep weed free and well watered. Once the fruits begin to swell, feed with a high potash feed once a fortnight. Rest large marrows and squash on upturned terracotta plant saucers or tiles, to prevent the bottoms rotting.
Trailing types can be grown over a wooden pallet or similar support to keep the fruit off the ground.
For marrows, train and remove side shoots to avoid overcrowding and encourage strong growth. It is best to limited marrow fruits to a maximum of four per plant at any one time to ensure good size fruits.
Susceptible to cucumber mosaic virus. Slugs, snails and mice may be a problem.
If a courgette or squash plant produces extremely bitter fruit then do not eat the fruits and discard the plant. The bitterness is caused by high levels of cucurbitacin, which if eaten can make you very unwell. Bitter fruits can occur where a plant is cross-pollinated with a wild or ornamental species that naturally contains high cucurbitacin levels.
Because it is not possible to tell if the seed within a fruit has been cross-fertilised, it is best not to save your own seeds from courgettes or squashes for future sowing but to buy fresh new seed from a certified supplier.
Courgettes and mini squash should ideally be harvested when small at about 4 inches (10 cm) long. Approximately 12 weeks after sowing. Pick the fruits regularly to keep the plant cropping. The flowers can also be eaten. Cloching at the end of the season can extend harvesting until October.
Marrows are cultivated in exactly the same way as courgettes but the fruits are left to fully develop on the plant. Marrows should be cut when firm and more than 9 inches (23 cm) long. When ready the skin should yield to gentle pressure. Marrows that have been left to mature on the plant to early October can be stored for later use.
Summer squash can be harvested from July onwards. Look for the stem beginning to split as evidence they are ready to cut. They are best used as soon as picked but will often store for a week or two in a cool dark place.
Harvest all courgettes, squash and marrow fruits
before the first frosts.
Courgettes and mini squash should be washed and trimmed before cooking. They can be sliced or diced and boiled in lightly salted water for 5 to 8 minutes. Alternatively slice and lightly pan-fry in butter or olive oil until tender.
The marrow's skin is not eaten as it will be too tough, so marrow are best peeled and deseeded. Marrows are good for stuffing and baking, either as rings or in halves. Marrow flesh can also be used in chutney and certain jam recipes.
The standard courgette colour is green but yellow forms are available and also other shapes such as globe or ball. Choosing varieties with an open habit allows maximum sunlight penetration for rapid fruit development and good air circulation to minimise disease. Harvest fruits regularly to extend the season.
Courgette 'Alfresco' (F1 Hybrid) produces creamy-green courgettes with a delicate flavour. Keeps well. Available at Marshalls and Mr Fothergills.
Courgette 'All Green Bush' a popular reliable variety that is fast maturing with a long season. Harvest as baby courgettes at about 4in (10cm) long for the best flavour. Available at Thompson & Morgan.
Courgette 'Black Forest' (F1 Hybrid) a unique climbing/trailing form, ideal for growing in containers on the patio. The long stems will need tying onto a trellis or netting for support. Heavy yields of dark green, smooth, cylindrical 6in (15cm) courgettes. Available at Thompson & Morgan.
Courgette 'British Summertime' (F1 Hybrid) is one of the earliest to set fruit. Good open habit. Available at Thompson & Morgan.
Courgette 'De Nice A Fruit Rond' produces a prolific crop of attractive small round fruits throughout summer. Available at Thompson & Morgan.
Courgette 'Defender' (F1 Hybrid) produces an abundance of firm, solid, green fruits. This disease resistant RHS AGM variety has a compact, open habit. Harvest from June to October. Available at Van Meuwen. Available at Thompson & Morgan.
Courgette 'Eclipse' (F1 Hybrid) produces excellent round, dark green, fruit that can harvested small to eat raw. Mature fruits are ideal for stuffing. Available at Thompson & Morgan.
Courgette 'El Greco' has an erect, open habit. Producing glossy, slightly speckled, mid green cylindrical fruits with a superb flavour and no bitterness. Available at Thompson & Morgan.
Courgette 'Firenze' (F1 Hybrid) high yields of small, slender glossy green courgettes throughout the summer. Open bushy habit and few spines making the fruits easy to harvest. Height: 45cm (18). Spread: 90cm (35). Available at Thompson & Morgan.
Courgette 'Jemmer' (F1 Hybrid) a vigorous hybrid that produces smooth, cylindrical bright yellow skinned fruits with a delicious flavour. Good resistance to powdery mildew. Available at Thompson & Morgan.
Courgette 'Midnight' (F1 Hybrid) a compact bushy plant producing delicious dark green, slightly-speckled courgettes. A compact form ideal for growing in containers on the patio. Available at Thompson & Morgan.
Courgette 'Modena' (F1 Hybrid) is a high yielding variety of deep green fruits with high disease resistance. Available at Marshalls.
Courgette 'Orelia' (F1 Hybrid) produces golden-yellow skinned fruits up to 10in (25cm) long, with an excellent flavour. Open habit and virtually spineless stems. Good mildew resistance. Harvest from June to October. Available at Van Meuwen. Available at Thompson & Morgan.
Courgette 'Parador' (F1 Hybrid) Golden yellow, cylindrical courgettes with a superb flavour and texture. Early maturing. Available at Thompson & Morgan.
Courgette 'Shooting Star' (F1 Hybrid) a climbing golden skinned variety. A space-saving plant when grown up a trellis/arch. The fruits are less watery than many varieties so are firmer when sliced for salads and stir fries. Available at Thompson & Morgan.
Courgette 'Soleil' (F1 Hybrid) produces smooth, straight, yellow fruits that are early maturing and harvest over a long period if cut regularly. An RHS AGM variety with a delicious flavour. Available at Thompson & Morgan.
Courgette 'Summer Ball' (F1 Hybrid) a compact plant that can be grown as a courgette or as a pumpkin. Cut early as courgettes or leave the fruits to mature to large 1kg (2lbs) summer pumpkins. Available at Thompson & Morgan.
Courgette Sunstripe has vibrant yellow fruits ideal for use for salads and barbeque skewers. Available at Van Meuwen.
Courgette 'Sure Thing' a self-pollinating type, ideal for a small garden or greenhouse. Speckled, dark green fruits. Available at Thompson & Morgan.
Courgette Tristan is packed with taste and produces a bountiful harvest. Available at Gardening Direct.
Courgette 'Tuscany' (F1 Hybrid) produces large yields of firm fleshed, dark fruits with good flavour. Available at Marshalls.
Courgette 'Venus' (F1 Hybrid) a compact RHS AGM variety ideal for patio containers. Provides heavy crops of delicious, shiny, dark green, cylindrical fruits. Available at Thompson & Morgan.
Courgette 'Zucchini' (F1 Hybrid) excellent all-round, high yielding variety that produces long dark green fruits with a fine delicate flavour. Available at Marshalls.
Marrow 'Long Green Bush' a popular early maturing variety with a compact habit and heavy yields. Can be harvested early as courgettes or grown to maturity for full sized marrows. Available at Thompson & Morgan.
Marrow 'Long Green Trailing' a traditional pale and green striped marrow on a trailing vine.
Marrow 'Tiger Cross' (F1 Hybrid) a striped green bush type marrow with good uniform fruits. Resistance to cucumber mosaic virus. The attractive fruits can either be cut at 4-6in (10-15cm) as courgettes or left to mature as marrows. Excellent lightly cooked or freshly picked. Suitable for winter storage. Available at Thompson & Morgan.
Squash 'Patty Pan' (scalloped squash or custard squash) is a popular flying saucer shaped, mini variety with pale green, white or yellow skin.
Squash 'Vegetable Spaghetti' is a pale yellow cylindrical squash, with unusual flesh that looks and cooks like spaghetti.