Cucurbit
How to grow courgettes
Cucurbita pepo
Sow courgettes singly in pots indoors from mid April, or outdoors in late May, and plant out only after the last frost into rich soil with plenty of compost. Give each plant a square metre, water generously at the base, and pick every two or three days once cropping starts, because a courgette left to become a marrow stops the plant flowering. Two plants feed most households.
- Hardiness
- Tender, frost kills it
- Position
- Full sun, sheltered
- Soil
- Very rich, moisture-retentive
- Ideal pH
- 6.0 to 7.0
- Water
- High, water the roots, not the leaves
- Feeding
- Heavy feeder
Sowing and planting courgettes
WhenSow Apr to May indoors or late May direct; plant out Jun; harvest Jul to Oct
Starting off
Sow indoors in mid April to May, one seed on its edge 2 cm deep in a 9 cm pot at 18 to 21 °C, germinating in 5 to 8 days; plant out in early June after hardening off for a week. Direct sowing under a cloche or jar works from late May once the soil is above 13 °C.
Spacing and planting
Plant 90 cm apart each way, or 60 cm for compact types, on a slight mound with a 30 cm planting hole filled with compost. Sow or plant 2.5 cm deep. One plant fills a 40 to 45 cm pot or a 40 litre bag; compact 'Patio Star' manages a 30 cm pot with daily watering.
Varieties worth growing
- Defender F1
- Dark green, very early and prolific, with resistance to cucumber mosaic virus. The default choice.
- Black Beauty
- Open-pollinated bush, reliable, seed can be saved.
- Gold Rush F1
- Yellow fruit that is easy to spot among the leaves, so fewer escape to marrow size.
- Tromboncino
- Climbing Italian type for a trellis or arch; long curved fruit, takes up less ground.
- Patio Star F1
- Compact bush for a 30 cm pot or a balcony.
Courgettes month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Order seed.
- February
Nothing. Too early even indoors.
- March
Prepare the planting station: a 30 cm hole filled with compost, made into a slight mound.
- April
Sow indoors from mid April, one seed on its edge 2 cm deep in a 9 cm pot at 18 to 21 °C.
- May
Sow a second batch early in the month. Harden off from late May. Direct sow under a cloche after the 20th.
- June
Plant out in the first week. Protect from slugs. Water at the base.
- July
First fruit. Pick every two days at 10 to 15 cm. Start the high-potash feed.
- August
Peak picking. Water heavily in dry spells. Remove mildewed leaves.
- September
Cropping slows. Let one fruit grow to a marrow if you want one.
- October
Clear plants after the first frost. Compost them.
- November
Dig compost into next year's station.
- December
Rest.
Feeding courgettes
Hungry and thirsty: a rich planting station does most of the work, then potash once the fruit comes.
Hungry and thirsty, plant on a compost-rich station and feed with a balanced-to-high-potassium feed once fruiting.
Feeding plan
Planting, beds
Fruit & Vegetable Fertiliser 4-5-6
100 g (a double handful) mixed into the compost-filled planting hole, one per plant.
Planting, pots
Fruit & Vegetable Fertiliser 4-5-6
5 g per litre of compost; 200 g through a 40 litre pot or bag.
First fruit setting
Fruit & Vegetable Fertiliser 4-5-6
50 g per plant as a top-dress round the stem, watered in. Pots: 2 to 4 g per litre of pot volume.
Every 7 to 14 days from first fruit
1 g per litre of water as a drench, or 20 to 50 g/m² dry in July.
Every 2 to 3 weeks in pots
1 to 2 g per litre of water; keeps the older leaves green under heavy potash.
Signs to watch
Fruit yellowing and rotting from the tip at 5 cm
Poor pollination in a cold, wet spell or erratic water, not calcium
Hand-pollinate with a male flower and water evenly
Older leaves yellow between the veins
Magnesium locked out by high-potash feeds
Epsom salts spray
All leaf, no female flowers
Excess nitrogen or cool weather
High-potash feed
Pests, diseases and problems
Seedlings and young plants grazed to stumps overnight
Slugs and snails
Plant out at a good size in June, ring with a copper collar or a cloche, go out with a torch for the first fortnight.
White powdery coating on older leaves from August
Powdery mildew, driven by dry roots and humid air
Water the roots generously and consistently, remove the worst leaves, and accept it on plants that have cropped for 10 weeks; a 1 in 10 milk spray slows it.
Leaves mottled yellow and puckered, fruit distorted and bumpy
Cucumber mosaic virus, spread by aphids
Pull and bin affected plants, control aphids on nearby plants, grow Defender.
Small fruit yellows and rots from the flower end at 5 cm
Poor pollination in cold wet weather, or dry roots
Hand-pollinate with a male flower (the one on a plain stalk) in the morning, water evenly, and wait for warmer weather; it stops on its own in July.
Grey fluffy mould on the fruit tip where the flower was
Botrytis entering through the fading flower in wet weather
Remove spent flowers from set fruit, pick small and often, cut away the mould.
Harvest and rotation
Harvest and storage
Cut at 10 to 15 cm long with the flower just withered, 8 to 10 weeks from sowing, severing the stalk with a knife; check every 2 days, as a missed fruit becomes a marrow and stops the plant. A plant gives 15 to 25 fruits, 3 to 4 kg, from July to the first frost. They keep a week in the fridge; grate and freeze.
Rotation and companions
Rotation: cucurbit group with squash, pumpkin and cucumber, 3-year gap; follows brassicas or legumes well on a manured bed.
Good to knowPlant on a slight mound and water at the base; pick regularly to keep new fruit coming.
Growing courgettes in pots
One plant fills a 40 to 45 cm pot or a 40 litre bag; Patio Star manages 30 cm. Fill with peat-free multipurpose mixed with a third garden compost or loam-based compost for water-holding, and the Fruit & Vegetable Fertiliser through it. A courgette in a pot in July needs 3 to 5 litres of water a day, so a saucer, a mulch and a drip line are not luxuries. Pot plants mildew earlier than bed plants because they dry out; keep them watered and you get a crop into October.
Courgettes: common questions
How often should I water courgettes?
Every day in pots in summer, two or three times a week in beds, and always at the base. Erratic water is behind most courgette problems: fruit rotting at the tip, bitter fruit, and early mildew.
Why does my courgette have flowers but no fruit?
Early flowers are usually all male. Female flowers have a tiny fruit behind them and come a week or two later, more once nights warm up. Cold weather and excess nitrogen both delay them.
Why are my courgettes rotting at the end?
The flower end rots when the fruit was not pollinated, usually in a cold wet spell. Hand-pollinate with a male flower in the morning. It is not blossom end rot in the tomato sense and not a calcium shortage.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.