Courgette: to sow, to plant, to grow in the vegetable garden

Description and Botany

Like all plants of the genus Cucurbita, courgette is native to the Americas, however the first selections of cultivated courgettes only appeared in the 18^th century in Italy. Unlike squashes, courgette is consumed at a juvenile stage, before the skin hardens and before the seeds form in the fruit. It is therefore harvested young, not mature.

Courgette – Cucurbita pepo var. pepo – is a fruit-vegetable of the family Cucurbitaceae, which includes many edible species cultivated by humans, such as squashes, melons, cucumbers, and watermelons. The pepo species includes both courgettes and also pattypans, pumpkins, and other oil squashes.

We find in courgette, as in most pepo, certain common characteristics: their habit is bushy, the leaves are distinctly lobed and prickly, as are the petioles and stems. The flowering of courgette is monoecious, bearing male flowers and female flowers on the same plant, in different locations. The female flowers bear the fruits, while the male flowers produce pollen. The blooming of a flower lasts only one day. Pollen is transported by pollinating insects such as bees and bumblebees, and the pollination is referred to as entomophilous. Additionally, courgette is allogamous, meaning it promotes cross fertilization with other varieties of the species or other plants of the same species.

A well-fertilized courgette flower will produce a fruit whose shape is characteristic of the variety; the most common shape is elongated and straight, more or less ribbed. It can also be flattened at the ends and present a round shape like the ‘Ronde de Nice’, with a neck or even club-shaped, like marrow squash. The colours range from light green to dark green, more or less marbled, to yellow and white. Courgette seeds are slightly rounded and grey to white in colour.

Above: Female flower in its entirety and close-up of the stigma of the pistil. Below: Male flower in its entirety, the peduncle is clearly visible and close-up of the stamen, where pollen grains can be observed.

Zucchini varieties

Grey, light green to dark green courgettes

Yellow courgettes

Round courgettes

Courgette Alberello di Sarzana - Ferme de Sainte Marthe Seeds

Aberello di Sarzana Courgette is an Italian variety with a bushy habit that produces long, ribbed fruits with smooth, light green skin, slightly marbled, with tender flesh and good taste quality even raw. It is early, has 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 Italian Non-Running Courgette or Coucourzelle is a variety that is ideally harvested when the fruits are young. Non-running and with a bushy habit, 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 Milan Green variety, also known as Black Beauty, is an early, very productive, non-running variety with an upright and compact habit, producing long, very dark green fruits that are almost black and should be harvested very young to fully enjoy their taste and texture qualities.

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

See the product sheet

Zucchini Grisette de Provence - Cucurbita pepo

The Provence or Greyzini Grisette Courgette is a non-running, early and productive variety that produces light green fruits, marbled with light grey. Its white flesh is crunchy 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 Genovese Courgette is an early Italian variety that produces elongated fruits with smooth skin, light green in colour, with good taste quality and firm white flesh. It is a productive, non-running courgette 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 Dark Green Black Market Gardener Courgette is cultivated 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 Firenze Courgette is a variety awarded by the prestigious Royal Horticultural Society! Slightly spiny and with 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 Gold Rush Courgette produces elongated, long and regular fruits, of a beautiful golden yellow, with fine, cream-coloured flesh and good taste quality. 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 Nice Round Courgette is a variety of courgette with spotted green, round fruits with fine, tender and melting flesh, ideal for stuffing. These courgettes are best harvested young, so regular harvesting 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 Yellow One Ball Courgette is an F1 hybrid variety that produces small, round, shiny golden yellow fruits that are sure to make an impression in your stuffed courgette dishes. Early and perpetual, this variety has good taste quality.

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

See the product sheet

Sowing courgette

Where and When to Sow Courgettes?

Sowing courgettes is preferably done in a bucket. However, it can also be done directly in open ground. Courgettes are among the greedy vegetables that thrive in rich, organic, loose, and deep soil. It is advisable to prepare the bed by adding compost at a rate of 3 to 4 kg per m².

Courgettes are sown:

• from mid-April to mid-May in a warm environment, indoors or in a heated shelter
• from mid-May to mid-July directly in open ground.

How to Sow Courgettes?

You can prepare young plants to be planted in the vegetable garden once all risk of frost has passed or sow directly in place.

Preparing Young Plants:

1. Fill pots or buckets with a good potting mix,
2. Place two seeds per pot (flat) at a depth of about 2 cm and cover with potting mix,
3. Water for the first time using the spout of the watering can

Keep warm and in the light (on a windowsill), at around 20°C, and maintain the substrate moist but not waterlogged until germination, which usually takes between 5 and 8 days. When the young plants are well-developed, thin them out, keeping only the strongest seedling.

Sowing courgette seeds in a bucket

Sowing in Open Ground, Directly in Place:

Sowing is done in clusters, in weeded and loosened soil, spacing the 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 and lightly compact,
3. Water for the first time, with a light rain to avoid displacing the seeds,
4. Keep the soil moist until germination.

After germination, when the young plants are well-developed, thin them out to keep only the best plant from each cluster.

Young courgette seedlings. To thin out… or transplant!

Planting courgettes: when and how

When to plant courgettes?

Courgette planting takes place from May, preferably after the Ice Saints, in regions most sensitive to cold. In the South, they can be planted as early as mid-April, monitoring the weather and possibly protecting them from the last frosts with a cover. It is possible to continue planting until July.

The planting distances are 1 m between each young plant and 1.3 m between the ranks. Note that these distances can be reduced depending on the varieties: “trailing” varieties spread more than “non-trailing” ones.

How to plant courgettes?

Courgettes require a well-manured soil, previously enriched with an addition of compost or well-rotted manure of 3 kg per m².

To plant your courgettes:

1. dig a hole corresponding to the volume of the root ball,
2. place the root ball and cover it with soil,
3. firm the soil and water to keep it moist,
4. to facilitate recovery, water regularly at the base.

→ Discover our tips for growing courgettes in pots

Cultivation, watering, and companion planting of courgette

Three well-maintained young plants of courgettes allow for a regular harvest of courgettes for a family of four. If your diet is predominantly vegetarian… or if you really love courgettes, don’t hesitate to plant more!

Regarding cultivation, it’s important to know that:

• harvesting the fruits encourages the production of a new flowering.
• Placing a slate or tile under the fruit to protect it is a good tip if the soil tends to retain moisture.
• Courgettes prefer cool soils in summer, remember to mulch around the young plants.
• Avoid watering the leaves or flowers, instead water at soil level using the spout of the watering can.
• Due to its significant growth, it is much more practical to grow courgettes alone; however, it is possible to grow them near basil, onion, and beans.

→ Pascale explains why courgettes do not produce.

Courgette cultivation in a greenhouse, ideal for harvesting earlier in the season

Common diseases

Powdery Mildew on Courgette

Powdery mildew is a cryptogamic disease (caused by a fungus) that manifests as white, powdery spots on the leaves, which eventually dry out, leading to reduced production and the plant may ultimately die. This disease appears when conditions are warm and humid. 27°C is the ideal temperature for the fungus to develop. Powdery mildew is common at the end of the season, so it is unnecessary to act at that time; however, when the plants are in full production, intervention is required. Here are some preventive and curative tips to apply:

• space the plants well during planting: 1 metre between each plant is advisable as they need air to allow the leaves to dry quickly in case of rain.
• Avoid fertilisers that are too rich in nitrogen; prefer a well-balanced compost!
• A keen eye will allow you to remove the first outbreaks by cutting off the affected leaves.
• The natural “magic potion” consists of diluted skimmed milk at a ratio of 1/10^th. Use it to spray on the affected leaves. Repeat this operation regularly to curb the spread of the fungus.
• In biodynamics, it is common to spray horsetail decoction to limit the arrival of the fungus.

→ Read also: Diseases and Pests of Squashes and Courgettes

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

Harvesting and Storing Courgettes

Young courgettes are much more flavoursome and should be consumed quickly after harvest, still crunchy. To harvest, it is preferable to cut the peduncle cleanly with a knife or pruning shear rather than twisting the courgette, as this tearing is a gateway to diseases.

Courgettes harvested later, after returning from holidays, can be consumed, but they will need to be emptied and peeled (the skin hardens). Their taste is, however, much less interesting than that of young courgettes, and they will be useful for soups and ratatouille.

Young courgettes can be stored for a few days in the bottom of the refrigerator. “Old” courgettes can be kept for a few weeks. Courgettes can also be stored cut into pieces and then frozen, or placed in jars and sterilised.

Harvesting courgettes

→ Also discover Ingrid’s tips on  lacto-fermentation

Uses and nutritional benefits

Courgettes are used in a variety of dishes: grated raw, or cooked in ratatouille, sautéed, tagliatelle, or of course stuffed – round varieties or large hollowed courgettes are ideal for this purpose. Less commonly, male and female courgette flowers are edible and are usually stuffed or cooked in fritters. In the case of the female flower, the pistil is removed, and the mini courgette is left attached to the flower.

Discover how to make courgette flower fritters?

Nutritionally, courgette is rich in minerals (potassium, magnesium, calcium) and vitamins, particularly provitamin A, vitamin B, and C. It also contains fibre and is very low in calories, making it an excellent weight-loss vegetable.

Making your courgette seeds

As we have seen previously, courgette is entomophilous and cross-pollinating, promoting cross fertilization with other varieties of the species or other plants of the same species, and this pollination occurs through the intervention of pollinating insects. Manual pollination is therefore recommended to ensure the preservation of the characteristics of the desired variety.

Manual Pollination of Courgettes

It is first recommended to grow several plants of the same variety, at least six plants. A selection of the most beautiful plants, conforming to the description of the variety and of good precocity, are kept and used 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 corolla is cream in colour. If you are unsure, observe the development of the flowers over several days to identify the stage just before the flowers open. Remember, the courgette flower only opens for one day!
2. Using clothespins, tie up the male and female flowers to prevent them from opening and to keep insects from pollinating them.
3. The next 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 stamens that carry the pollen.
5. Remove the clothespin from the female flower and gently open the corolla.
6. Gently spread the 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 clothespin.
8. Clearly mark the pollinated flowers using stakes, for example.

The pollinated courgettes should be harvested when mature, that is, when the peduncle becomes dry and the skin of the courgette changes colour and hardens. Once harvested, the courgettes are kept for a month before extracting the seeds. To separate them from the flesh, soak them in water and let them dry well in a warm, ventilated place for several days before bagging them.

Learn more about manual pollination of courgette flowers