A Complete Guide to growing courgettes in the UK.

Introduction

Courgettes (zucchini) are one of the most productive crops for UK gardens. A single plant can yield dozens of fruits over summer, making them a favourite for both beginners and seasoned growers. Easy to establish, fast-growing, and versatile in the kitchen, they can be harvested young as tender courgettes or left to mature into marrows. With a range of compact and trailing varieties available, courgettes can be grown in beds, raised borders, or large containers.

Types and Timing

Courgettes come in different shapes and colours:

Green courgettes: The most common type, reliable and heavy-cropping.
Yellow courgettes: Bright, tender fruits with a slightly sweeter taste.
Round courgettes: Perfect for stuffing and roasting.
Compact/bush varieties: Ideal for small gardens and containers (‘Patio Star’).
Trailing types: Vigorous and space-hungry, but very high yielding.

Timing:

Sow indoors from late March to May.
Sow directly outdoors from late May to early June, after frosts.
Plant out from late May onwards, once seedlings are hardened off and frost risk has passed.

Site and Soil Requirements

Courgettes thrive in warm, fertile ground:

Light: Full sun, sheltered from strong winds.
Soil: Rich, moisture-retentive but free-draining. Courgettes are heavy feeders.
Preparation: Improve soil with compost or well-rotted manure before planting.
Containers: Large pots (at least 30-40 cm wide) filled with rich compost work well. Growbags are also popular.

Propagation & Planting

Indoor sowing: Sow one seed per small pot, 2-3 cm deep, kept at 18-21°C. Seeds germinate in 7-10 days.
Hardening off: Acclimatise indoor seedlings before planting outside.
Outdoor sowing: Sow 2 seeds at each planting station 90 cm apart; thin to the strongest seedling.
Spacing: Allow 90 cm between plants, or more for sprawling varieties. Compact types can be grown closer.

Growing & Maintenance

Watering: Keep soil consistently moist—courgettes are thirsty plants. Water at the base to avoid wetting leaves.
Feeding: Start weekly feeding with a high-potash fertiliser once plants begin to flower.
Mulching: Retains moisture and keeps fruit clean.
Pollination: Flowers are male or female. If fruit fails to set in poor weather, hand-pollinate by transferring pollen from male to female flowers.
Training: Bush varieties stay compact; trailing ones can be guided across the soil or supported on a frame.
Flower use: Courgette flowers are edible and can be picked for cooking, though leave enough for fruiting.

Harvest and Post-Harvest

Harvesting: Pick fruits when 10-15 cm long for best flavour and texture. Check plants every few days, as courgettes grow quickly.
Frequency: Regular picking encourages more fruit. If left, courgettes will swell into marrows, slowing further production.
Storage: Fresh courgettes keep 4-5 days in the fridge. For longer storage, they can be grated and frozen for use in soups or baking.
Uses: Roast, fry, grill, add to pasta, soups, or bake into breads and cakes.

Troubleshooting & Pests

Powdery mildew: White coating on leaves in late summer. Prevent with regular watering and good spacing. Remove affected leaves.
Slugs and snails: Attack young seedlings—protect with barriers, traps, or wildlife-friendly methods.
Poor fruit set: Usually due to poor pollination in cool/wet weather. Try hand-pollinating.
Rotting fruits: Often caused by irregular watering. Keep moisture consistent.
Yellowing leaves: Can indicate nutrient deficiency—apply liquid feed.

Tips from Growers / FAQs

Best for beginners: ‘Defender’ (green, disease resistant) and ‘Soleil’ (yellow, prolific).
Continuous harvest: Grow 2-3 plants to ensure a steady supply, but avoid planting too many—yields are generous.
Space-saving idea: Train trailing varieties up a trellis or obelisk.
Succession: For prolonged harvest, sow a second batch in June for late summer crops.
Cooking tip: Pick baby courgettes for tender texture; larger ones are ideal for stuffing or stews.

Resources & References

RHS: Grow Your Own Courgettes
BBC Gardeners’ World: How to Grow Courgettes