Courgette

About Courgette

Courgettes are one of the most productive and rewarding vegetables for a UK kitchen garden, capable of producing a glut of fruit from just two or three plants from July through September. Picked young at 10–15 cm they are tender and mild; left to grow they become marrows. Plants are large and vigorous — each sprawling bush needs roughly a square metre of space — and they reward regular feeding and watering with a continuous harvest. Yellow varieties such as 'Soleil' and compact patio types such as 'Patio Star' are popular for smaller gardens. The large yellow flowers are also edible, and a summer staple in Italian cuisine.

UK fact: The word 'courgette' is French, from 'courge' (gourd); in American English and in much of the world outside the UK they are known as zucchini. The UK's climate suits courgettes well — the cool nights and moderate summer temperatures slow them slightly compared with the Mediterranean, but also prevent the bitterness that develops when cucurbit plants are heat-stressed.

Watering Courgette

Courgettes need consistent, generous watering — a large plant in full fruit can need 5–10 litres per day in warm weather. Irregular watering causes poor fruit set and blossom end rot.

Courgettes have very high water requirements once they begin fruiting. Water at the base, never over the leaves, to reduce the risk of powdery mildew. In dry summer weather, established plants need watering every day or every other day — a thorough soak that reaches the deep roots, rather than a light surface spray. Young plants before fruiting can be watered less frequently (every 2–3 days). Apply a thick mulch of compost or bark chippings around the root zone to reduce evaporation and maintain consistent soil moisture. Water stress during fruit development leads to misshapen courgettes, blossom drop, and blossom end rot.

Sunlight requirements

Courgettes need full sun and a warm, sheltered position — a south-facing bed or the warmest spot in the kitchen garden produces the heaviest crops.

Courgettes require full sun to crop well — at least six hours of direct sun per day. A warm, sheltered position protects the large leaves from wind damage and accelerates fruit development. In shadier positions, plants produce more foliage and fewer fruits, and are more susceptible to powdery mildew. In cooler parts of the UK, growing against a south-facing wall or under a cloche for the first few weeks after planting significantly improves yields.

Soil and feeding

Rich, moisture-retentive soil with plenty of well-rotted compost or manure incorporated before planting — courgettes are hungry plants that repay generous soil preparation.

Courgettes are hungry, thirsty plants that need deeply cultivated, fertile soil. Dig in a generous amount of well-rotted compost or manure before planting — ideally a whole bucketful per planting hole. They prefer a slightly acid to neutral pH of 5.5–6.8. Good drainage is important: while they need consistent moisture, waterlogged roots will cause collar rot. On heavy clay soils, mound the soil slightly to improve drainage. Container growing is possible in very large pots (minimum 40–50 litres) with a rich compost blend.

Feed with a high-nitrogen liquid fertiliser early in the season to build the plant; switch to a high-potash feed once flowers appear to direct energy into fruit production.

Before planting, work a balanced slow-release granular fertiliser into the soil. During the early growing period, apply a high-nitrogen liquid fertiliser (such as a seaweed extract or general balanced feed) every two weeks to support rapid leaf and stem growth. Once the first flowers appear — usually in July — switch to a high-potash liquid feed (tomato fertiliser is ideal) applied weekly. This channels the plant's energy from foliage into fruit. Pot-grown plants need feeding more frequently, approximately twice a week at half strength once fruiting begins.

Pruning Courgette

No regular pruning needed, but removing the oldest, yellowing leaves in late summer improves air circulation and reduces mildew; pick fruit regularly to keep plants productive.

Courgettes do not need pruning in the traditional sense. However, regular harvesting is essential — it functions like deadheading on flowering plants. Leaving courgettes to grow into marrows signals the plant to stop setting new fruit. Pick every 2–3 days during peak season, harvesting courgettes at 10–15 cm for the best flavour and texture. In late summer, remove the oldest and most yellowing leaves at the base of the plant to improve air circulation, which helps reduce powdery mildew. If space is very limited, the main growing shoot of a trailing variety can be pinched out to restrict spread.

Propagating Courgette

Sow seeds indoors in 9 cm pots in late April or early May; courgettes grow so fast they do not need early sowing — plants become too large if started in March.

Courgettes are grown from seed each year and are surprisingly quick to germinate and grow — do not be tempted to sow too early. Sow in late April to early May indoors, placing one seed on its side at 2.5 cm depth in a 9 cm pot of seed compost. Germinate at 18–20°C; seedlings emerge in 5–7 days. Grow on in a warm, bright position and pot on into a larger container if roots fill the pot before planting-out time. Harden off thoroughly over 10–14 days before planting out after the last frost risk (end of May in the south, early June in the north and Scotland). Courgettes can also be direct-sown outdoors under a cloche from late May.

1. 1Sow indoors in late April

   Fill a 9 cm pot with seed compost. Place one seed on its side at 2.5 cm depth — laying it flat prevents water sitting on the seed and causing rot.

2. 2Germinate at warmth

   Place on a warm windowsill or in a heated propagator at 18–20°C. Seedlings emerge in 5–7 days. Do not let the compost dry out.

3. 3Pot on if needed

   If the plant's roots fill the pot before it is safe to plant outside, pot on into a 1-litre or 2-litre pot to prevent it becoming pot-bound.

4. 4Harden off outdoors

   From mid-May, place plants outdoors in a sheltered spot during the day and bring them in at night. Do this for 10–14 days to acclimatise them to outdoor temperatures.

5. 5Plant out after frost risk

   Plant out in late May (south) to early June (north), once all risk of frost has passed. Dig a planting hole, incorporate a generous amount of compost, and water in well. Allow 90 cm–1 m between plants.

Common problems

Powdery mildew is almost inevitable on courgettes by late summer, producing a white powdery coating on the leaves. It does not usually kill the plant but weakens it and reduces yield. Improve air circulation by removing lower leaves and avoid overhead watering. Blossom end rot causes the developing fruit to rot at the flower end; it is caused by calcium deficiency linked to irregular watering — improve moisture consistency. Poor fruit set (lots of flowers but no courgettes forming) is usually due to a lack of pollinators or cold weather; try hand-pollinating by transferring pollen from male flowers (on a long, thin stem) to female flowers (which have a tiny embryo fruit at the base) using a small paintbrush. Cucumber mosaic virus causes yellow mosaic mottling on leaves and distorted fruit; there is no cure — remove and dispose of affected plants. Slugs attack young transplants; protect with slug pellets or copper tape.

The Loam app can help identify what's wrong with your plant — photograph the affected leaves and it will suggest the most likely cause.

Seasonal care calendar

Monthly care guide for Courgette in the UK, based on average conditions.

Frequently asked questions

When should I sow courgettes in the UK?

Sow courgettes indoors in late April to early May — no earlier. They germinate and grow so quickly that plants sown in March become root-bound and stressed before it is safe to plant outside. Seeds sown in late April will catch up with earlier sowings by July and crop just as well.

Why are my courgette plants flowering but not producing fruit?

Courgette plants produce separate male and female flowers on the same plant. Poor fruit set is usually because female flowers are not being pollinated — either there are not enough pollinators visiting the garden, or the weather is too cold and cloudy for bees to be active. Try hand-pollinating: use a small paintbrush or cotton bud to transfer pollen from a male flower (which sits on a long, thin stem) to the centre of a female flower (which has a tiny embryo courgette at its base).

How often should I water courgettes?

In warm, dry summer weather, a large courgette plant in full production needs watering every day or every other day — a generous soak of 5–10 litres at the base of the plant, not over the leaves. Inconsistent watering is the most common cause of poor yield and problems such as blossom end rot. Laying a thick mulch of compost around the root zone dramatically reduces how often you need to water.

My courgette has grown into a marrow — can I still eat it?

Yes — marrows are simply courgettes that have been left to grow large. They are perfectly edible, though the texture is softer and the flavour milder. Larger marrows (over 30 cm) are best stuffed and baked rather than sliced and fried. The key lesson is to check plants every two to three days during summer, as courgettes can grow from 10 cm to marrow size in less than a week.

Can I grow courgettes in a container?

Yes, but use the largest container you can manage — a minimum of 40–50 litres. Compact patio varieties such as 'Patio Star' and 'Astia' are bred specifically for container growing. Use a rich, moisture-retentive compost and be prepared to water daily in hot weather. Feed twice a week with a high-potash liquid fertiliser once fruiting begins. Container-grown plants are more vulnerable to drying out and will not be as productive as those in open ground.

Related plants

• Lavender
• Sweet Pea