When to plant

UK crop guide

Courgettes

Cucurbita pepo

One courgette plant is usually enough. In a decent summer the RHS expects three or four fruits a week, and they get out of hand the week you go away.

They are tender. Sow them indoors in mid to late spring, or outdoors in late May or early June once the soil is warm, and do not plant them out until early summer.

  • Sow indoors in April and May. Mid to late spring, in individual pots.
  • Sow or plant outside in May and June. Outdoor seed in late May or early June. Indoor plants go out in early summer, after hardening off.
  • Harvest in July, August and September. Through the summer, while the fruits are still small. Regular picking keeps them coming.

Sow indoors

Sow in mid to late spring, one seed to a small pot, on its edge, and keep the pot warm. Gardeners' World includes courgettes with the April sowings that still need a greenhouse or a sunny windowsill. A May sowing under cover is still in good time, and it avoids a huge plant waiting for the last frost.

Pot on if the roots fill the pot before planting time. Harden the plants off before they go outside for good.

Sow or plant outdoors

In late May or early June, once the soil has warmed, sow two or three seeds 2.5cm deep where the plant will grow, at least 90cm from the next plant. Thin to the strongest seedling. This is more reliable in warmer parts of the country. Slugs will target the seedlings, so sow a spare.

Prepare the spot with plenty of garden compost or well-rotted manure. Courgettes are hungry and they need water once they are flowering.

Plant out

Indoor-sown plants, and plants bought in late spring, go out in early summer after hardening off. Set each plant in the middle of its prepared patch, at least 90cm from its neighbour, and water it in. In a cool region, check the frost page before you commit. A fleece on a cold night is worth having for the first fortnight.

You can also grow a plant in a large container, but it will need more watering than one in the ground. Give it the same sort of room: a cramped plant mildews and crops poorly.

Spacing and depth

Between plants
At least 90cm
Outdoor seed depth
2.5cm
Fruits
Cut at 10 to 12.5cm long

Harvest

Cut fruits at 10 to 12.5cm, while they are firm and the flower may still be attached. A courgette left on the plant becomes a marrow and the plant slows down. Check the plant every couple of days in July and August.

Male flowers, the ones with a plain stem rather than a tiny fruit behind them, can be picked for the kitchen without reducing the crop. Leave some males if you are relying on insects to pollinate.

Common problems

Slugs on young plants

The RHS flags slugs and snails as the main threat just after planting. A plant that has been raised in a pot and planted out stocky survives better than a seedling in the open row. Protect the stem area for the first weeks.

A plant that stalls

Courgettes need warmth, rich soil and steady water once they are flowering. A plant put out before early summer, into cold soil, sits and sulks. Wait for your frost window, then water in dry spells.

A marrow by accident

If you want courgettes rather than marrows, cut them small and keep cutting. One overlooked fruit is enough to slow the whole plant.

What you'll need

Kit for this crop, based on the method above.

  • Peat-free multi-purpose compost

    For pots, modules and containers once seedlings need more body.

  • Module trays or small pots

    For crops started under cover. Deep pots suit peas, beans and sweetcorn.

  • Garden compost or well-rotted manure

    Dug or mulched in before planting. Do not use fresh manure.

  • Horticultural fleece

    For early sowings and for covering tender plants if a late frost is forecast.

  • Watering can with a rose

    A fine rose avoids washing small seed out of the drill.

  • Labels

    Variety and sowing date, so succession sowings do not get mixed up.

Common questions

How many courgette plants do I need?

Often one. The RHS says a plant in good weather can give three or four fruits a week. Two plants is plenty for most households, and they each need at least 90cm of room.

Can I sow courgettes outside?

Yes, in late May or early June, 2.5cm deep, once the soil is warm. Indoor sowing in April or May is more reliable, especially outside the south.

On the calendar

Related crops

Sources

  1. RHS: How to grow courgettes. Checked 11 October 2026.
  2. BBC Gardeners' World: Your seed-sowing year. Checked 11 October 2026.