Courgette: Sowing, Planting and Growing in the Vegetable Garden

Description and botany

Like all plants in the Cucurbita genus, courgettes originate from the Americas, however the first cultivated courgette varieties only appeared in the 18^th century in Italy. Unlike squashes, courgettes are eaten at a juvenile stage, before the skin hardens and before seeds form in the fruit. They are therefore harvested young, unripe.

The courgette – Cucurbita pepo var. pepo – is a fruit-vegetable from the Cucurbitaceae family, which includes many edible species cultivated by humans, such as squashes, melons, cucumbers and watermelons. The pepo species includes both courgettes as well as pattypan squashes, pumpkins and other oilseed squashes.

Courgettes, like most pepo, share certain common characteristics: they have a bushy growth habit, the leaves are distinctly lobed and prickly, as are the petioles and stems. Courgette flowering is monoecious, bearing both male flowers and female flowers on the same plant, at different locations. Female flowers bear fruit, male flowers produce pollen. Each flower blooms for just one day. Pollen is transported by pollinating insects like bees and bumblebees, making the pollination entomophilous. Additionally, courgettes are allogamous, meaning they favour cross-fertilisation with other varieties of the species or other plants of the same species.

A well-pollinated courgette flower will produce fruit with a shape characteristic of the variety – the most common form being elongated and straight, more or less ribbed. They can also be flattened at the ends and round in shape like the ‘Ronde de Nice’, with a neck or even club-shaped, like marrow types. Colours range from light green to dark green with varying marbling, to yellow and white. Courgette seeds are slightly convex and grey to white in colour.

Top: Female flower in full view and close-up of the pistil stigma. Bottom: Male flower in full view, the peduncle is clearly visible and close-up of the stamen showing pollen grains.

Varieties of courgette

Grey, light green to dark green courgettes

Yellow courgettes

Round courgettes

Courgette Alberello di Sarzana - Ferme de Sainte Marthe Seeds

The Courgette Aberello di Sarzana is an Italian variety with a bushy habit, producing long, ribbed fruits with light green skin slightly marbled, with tender flesh and good flavour even when raw. It is early, with good hardiness and productivity.

• Flowering time June to August
• Height at maturity 50 cm

See the product sheet

Non-trailing Zucchini - Vilmorin seeds - Cucurbita pepo

The Courgette non coureuse d'Italie or Coucourzelle is a variety best harvested when the fruits are young. Non-running and bushy, it produces elongated, smooth green fruits striped with yellow.

• Flowering time June to August
• Height at maturity 50 cm

See the product sheet

Zucchini Black Beauty - Cucurbita pepo

The Verte de Milan variety, also called Black Beauty, is an early, very productive, non-running variety with an upright, compact habit. It produces long, very dark green, almost black fruits that should be picked very young to best enjoy their flavour and texture.

• Flowering time June to August
• Height at maturity 50 cm

See the product sheet

Zucchini Grisette de Provence - Cucurbita pepo

The Courgette Grisette de Provence or de Greyzini is a non-running, early and productive variety that produces light green fruits marbled with light grey. Its white flesh is crisp and fine, best harvested young.

• Flowering time August, September
• Height at maturity 50 cm

See the product sheet

Courgette Genovese - Ferme de Sainte Marthe Seeds

The Courgette Genovese is an early variety of Italian origin that produces elongated fruits with smooth, light green skin and good flavour. The flesh is white and firm. This is a productive courgette, non-running and with a bushy habit.

• Flowering time June to August
• Height at maturity 50 cm

See the product sheet

Courgette Verte Noire Maraîchère - Vilmorin Seeds

The Courgette verte noire maraîchère is grown for its elongated, dark green fruits as well as its male flowers, which are slightly swollen and ideal for cooking. This non-running variety is early, very productive and fast-growing.

• Flowering time June to August
• Height at maturity 50 cm

See the product sheet

Zucchini Firenze - Cucurbita pepo

The Courgette Firenze is a variety awarded by the prestigious Royal Horticultural Society! With few spines and an open habit, Firenze produces small, elongated, dark green and shiny fruits with excellent flavour, of course!

• Flowering time June to August
• Height at maturity 45 cm

See the product sheet

Yellow Courgette - Ferme de Sainte Marthe Seeds

The Courgette Gold Rush produces elongated, long and regular fruits of a beautiful golden yellow, with creamy, fine flesh and good flavour. An early and productive variety, non-running and bushy.

• Flowering time June to August
• Height at maturity 50 cm

See the product sheet

Courgette Nice à fruit rond - Vilmorin Seeds

The Courgette de Nice à fruit rond is a variety of courgette with spotted, round green fruits with fine, tender and melting flesh, ideal for stuffing. These courgettes are best harvested young, so regular picking is recommended. This variety is very productive and non-running.

• Flowering time June to August
• Height at maturity 50 cm

See the product sheet

Zucchini Jaune One Ball - Cucurbita pepo

The Courgette Jaune One Ball is an F1 hybrid variety that produces small, round, golden yellow and shiny fruits that are sure to make a statement in your stuffed courgette dishes. Early and remontant, this variety has good flavour.

• Flowering time July to September
• Height at maturity 60 cm

See the product sheet

Sowing courgettes

Where and When to Sow Courgettes?

Courgettes are best sown in pots, though they can also be sown directly in the ground. Courgettes are hungry vegetables that thrive in soil rich in organic matter, loose and deep. Prepare the bed by adding compost at a rate of 3 to 4 kg per m².

Courgettes can be sown:

• from mid-April to mid-May indoors or in a heated greenhouse
• from mid-May to mid-July directly in the ground.

How to Sow Courgettes?

You can either prepare seedlings to transplant into the vegetable patch once all risk of frost has passed or sow directly in place.

Preparing Seedlings:

1. Fill pots or containers with good potting compost,
2. Place two seeds per pot (flat) at a depth of about 2 cm and cover with compost,
3. Water gently using a watering can.

Keep in a warm, bright spot (such as a windowsill) at around 20°C, keeping the compost moist but not waterlogged until germination, which usually takes 5 to 8 days. Once the seedlings are well developed, thin them out, keeping only the strongest plant.

Sowing courgette seeds in pots

Direct Sowing in the Ground:

Sow in stations, in weed-free and loosened soil, spacing plants one metre apart in all directions:

1. Dig holes 2 to 3 cm deep,
2. Place three seeds per hole and cover with fine soil, then firm lightly,
3. Water gently with a fine spray to avoid displacing the seeds,
4. Keep the soil moist until germination.

After germination, when the seedlings are well developed, thin them out, keeping only the strongest plant per station.

Young courgette seedlings. Thin out… or transplant!

Planting Courgettes: When and How

When to Plant Courgettes?

Courgettes should be planted from May onwards, preferably after the Ice Saints in regions more prone to cold. In the South of France, they can be planted as early as mid-April, keeping an eye on the weather and protecting them from late frosts with fleece if necessary. Planting can continue until July.

Space plants 1 m apart with 1.3 m between rows. Note that these distances can be reduced depending on the variety: “trailing” types spread more than “bush” varieties.

How to Plant Courgettes?

Courgettes require well-manured soil, previously enriched with compost or well-rotted manure at 3 kg per m².

To plant your courgettes:

1. dig a hole matching the size of the root ball,
2. place the root ball and cover with soil,
3. firm down and water to keep the soil moist,
4. water regularly at the base to help establishment.

→ Also discover our tips for growing courgettes in pots

Growing, watering and companion planting for courgettes

Three well-maintained courgette plants will provide regular harvests for a family of four. If your diet is predominantly vegetarian… or you’re particularly fond of courgettes, don’t hesitate to plant more!

Regarding cultivation, it’s good to know that:

• harvesting the fruits encourages new flowering.
• Placing a slate tile or roofing tile under the fruit to protect it is a handy tip if the soil tends to retain moisture.
• Courgettes appreciate cool soil in summer, so remember to mulch around the plants.
• Avoid watering the leaves or flowers—water at soil level using the spout of your watering can.
• Due to their vigorous growth, courgettes are much easier to grow on their own, though they can be planted near basil, onions, and beans.
  

→ Pascale explains why courgettes sometimes fail to produce.

Growing courgettes in a greenhouse—ideal for an earlier seasonal harvest.

Common diseases

Powdery Mildew on Courgettes

Powdery mildew is a fungal disease (caused by a fungus) that appears as white, powdery spots on leaves, which eventually dry out, reducing yield and potentially killing the plant. This disease thrives in warm, humid conditions, with 27°C being the ideal temperature for fungal growth. Powdery mildew is common late in the season, so treatment is unnecessary at that stage. However, when plants are in full production, action should be taken. Here are some preventive and curative tips to follow:

• Space plants well when planting: 1 metre between each plant is advisable to allow good air circulation, helping leaves dry quickly after rain.
• Avoid nitrogen-rich fertilisers—opt for well-balanced compost instead!
• Keep a close eye on plants and remove early infections by cutting off affected leaves.
• A natural “magic potion” can be made with diluted skimmed milk (1 part milk to 10 parts water). Spray this solution onto affected leaves and repeat regularly to prevent the fungus from spreading.
• In biodynamic gardening, spraying horsetail decoction is a common method to inhibit fungal growth.

→ Read also: Diseases and Pests Affecting Squash and Courgettes

Powdery mildew on a courgette leaf. It is also visible on the petiole.

Harvesting and Storing Courgettes

Young courgettes are far more flavoursome and best eaten soon after harvesting, while still crisp. When harvesting, it’s preferable to cleanly cut the stem using a knife or secateurs rather than twisting the courgette off, as this tearing can invite disease.

Courgettes harvested later, perhaps after returning from holiday, can still be eaten but should first be hollowed out and peeled (the skin toughens). Their flavour, however, is far less appealing than young courgettes, though they remain useful for soups and ratatouilles.

Young courgettes keep for a few days in the fridge’s vegetable drawer. Older courgettes can be stored for several weeks. Courgettes also preserve well when chopped and frozen, or jarred and sterilised.

Harvesting courgettes

→ Also discover Ingrid’s advice on lacto-fermentation preservation

Uses and Nutritional Benefits

Courgettes can be used in a variety of dishes: grated raw, or cooked in ratatouille, stir-fries, tagliatelle, or of course stuffed – the round varieties or large hollowed-out courgettes are ideal for this purpose. Slightly less common, both male and female courgette flowers are edible and are typically stuffed or cooked as fritters. For the female flower, the pistil is removed, while the tiny courgette is left attached to the flower.

Discover how to make courgette flower fritters?

From a nutritional standpoint, courgettes are rich in minerals (potassium, magnesium, calcium) and vitamins, particularly provitamin A, and vitamins B and C. They also contain fibre and are very low in calories, making them an excellent slimming vegetable.

Saving Your Own Courgette Seeds

As we’ve seen previously, the courgette is entomophilous and allogamous, favouring cross-fertilisation with other varieties of the species or other plants of the same species, with this pollination occurring through the action of pollinating insects. Hand pollination is therefore recommended to ensure the desired variety’s characteristics are preserved.

Hand Pollination of Courgettes

It is first recommended to grow several plants of the same variety, at least six plants. Select the finest plants that match the variety’s description, with good early vigour, to keep and use for seed production.

1. The day before pollination, identify the female flowers to be pollinated and the male flowers that will provide the pollen – at this stage, their corollas are cream-coloured. If unsure, observe the flowers’ development over several days to pinpoint the stage just before they open. Remember, courgette flowers only open for a single day!
2. Using clothes pegs, tie off the male and female flowers to prevent them from opening and to stop insects from pollinating them.
3. The following morning, pick the tied male flowers from one plant to pollinate another plant of the same variety.
4. Cut the corolla of the male flower to expose the pollen-bearing stamens.
5. Remove the peg from the female flower and gently open the corolla.
6. Carefully spread pollen from two to three male flowers onto the stigma (pistil) of the female flower.
7. Re-tie the corolla of the female flower with a clothes peg.
8. Clearly mark the pollinated flowers, for example with stakes.

Pollinated courgettes should be harvested when fully mature, meaning when the stem dries out and the skin changes colour and hardens. Once picked, the courgettes should be stored for a month before extracting the seeds. To separate them from the flesh, soak them in water and allow them to dry thoroughly in a warm, well-ventilated area for several days before bagging.

Learn more about hand-pollinating courgette flowers