When should I sow courgette seeds in the UK?

Late April to early May indoors; late May direct outdoors in southern England. Don't sow too early — courgette seedlings hate cold and grow leggy on a windowsill. Two plants per gardener is usually enough; one for a single person. They produce more than you'll know what to do with.

Why are my courgette flowers not setting fruit?

Either you've only got male flowers (which open first, on long stalks, with no bulge at the base), or the female flowers aren't being pollinated. Male flowers appear 1–2 weeks before females — wait, both will come. If females drop without setting, the weather is too cool or wet for pollinators; hand-pollinate by transferring pollen from a male flower with a small paintbrush.

How big should I let my courgettes grow?

15 cm is the ideal length — tender and full of flavour. Over 20 cm the texture coarsens; over 30 cm they're marrows, which need long cooking and stuffing to be palatable. Pick every two or three days during the peak; miss a week and you'll have marrows whether you wanted them or not.

Can I grow courgettes in containers in the UK?

Yes — bush varieties (Defender, Patio Star) do well in 30-litre containers. Use rich compost; water consistently; feed weekly with a high-potash liquid feed. Place in a sunny sheltered spot. Yields are lower than ground plants but you'll still get more fruit than you need from one plant.

How do I treat powdery mildew on courgettes?

Remove the worst affected leaves to improve airflow. Water only at the base of the plant, never the foliage. Mulch heavily to retain soil moisture — mildew is worse when roots are dry. A milk spray (1 part milk to 9 parts water, weekly) helps; cultivar Defender has good mildew resistance.

Are courgette flowers edible?

Yes — pick male flowers (long thin stems and no fruit forming), stuff or batter and fry. Pick in the morning when they're fully open. Picking male flowers doesn't reduce fruit production; you only need a few to pollinate the females. Female flowers can be eaten with the small courgette attached.

Courgette / zucchini

Cucurbita pepo

vegetable☀️ full-sun🪴 rich loam📏 medium🌡️ RHS H1c

📋Quick Facts

Height

0.5-0.6m

Spread

0.9-1.2m

Water

💧💧 Average watering

Hardiness

Zone 2-11

About

Sow courgette seed indoors from late April, or direct from late May once the soil is warm. Plant out after the last frost: mid-May in southern England, early June in the north. Courgettes are frost-tender (RHS H1c) and need warmth to set fruit. Space them 90 cm apart in rich, deep soil with plenty of compost dug in — they're hungry plants. From late July a single plant produces a fruit every two or three days; pick them at 15 cm before they balloon into marrows. The UK summer suits them perfectly, which is why they're the easiest crop to over-grow. Watch for powdery mildew in dry weather.

Top tip

Plant into rich soil, water generously, and pick fruits small and frequently to avoid marrows.

Also known as: Courgette / zucchini, Curgete, Zucchina, Zucchini, Cucurbita pepo, Cukinia, Courgette, Calabacín

How to grow courgette / zucchini

1
Sow seed indoors
Late April to early May. Set one seed on its side in a 9 cm pot of multi-purpose compost. 18–22°C on a windowsill or in a propagator. Germination in 5–7 days.
2
Pot on if needed
If the roots fill the pot before it's safe to plant out, pot on to a 1-litre pot. Don't let courgette seedlings get pot-bound — they sulk and check growth.
3
Prepare the bed
Fork compost or well-rotted manure into the bed in early May. Courgettes are hungry plants; the richer the better. A sunny sheltered position is essential.
4
Harden off and plant out
Harden plants off for 7–10 days. Plant out from mid-May in southern England, early June in the north. Space 90 cm apart for trailing varieties, 60 cm for bush. Water in well.
5
Water and feed
Water at the base every few days; never on the leaves. A weekly high-potash feed from the first flowers helps fruit set. Mulch with grass clippings to hold moisture.
6
Pick young and often
From late July, check daily. Pick when 15 cm long — about every two or three days at the peak. A week away on holiday guarantees marrows.
7
Watch for mildew
Powdery mildew (white dusty patches on leaves) is common from August onwards, especially in dry weather. Mulch heavily, water at the base, remove affected leaves. The plants usually crop through it anyway.

Common questions

Pest Resilience

2/5 — Somewhat vulnerable

Slugs love courgettes; powdery mildew is almost inevitable later in the season.

Companion Planting

Grows well with

French bean Nasturtium Sweetcorn

Keep apart from

Potato

Visual Characteristics

Fruits

Yes

Harvest: Summer to autumn / fall

🍳

Culinary

Culinary Use

Grilled, ratatouille, pasta, fritters, stuffed, stir-fries, tempura

The courgette / zucchini year in your garden

Dispatching imaginary bots to check your garden out...

What to do now

How to Propagate

🌰Seed

Easy

This plant produces viable seeds for propagation

Hardiness Zones

H1a (tender)H7 (very hardy)

H1a

H1b

H1c

RHS H1c

USDA 10–11 equivalent