Cucurbit
How to grow marrows
Cucurbita pepo
A marrow is the same species as a courgette, grown from varieties bred to be left on the plant until the fruit is 20 to 30 cm long or more. Sow indoors from mid April, plant out in early June in full sun on a mound of rich soil, and never let it dry out. Cut some young for the kitchen and leave the last few to harden in September for storing.
- Hardiness
- Tender
- Position
- Full sun
- Soil
- Very rich, moisture-retentive
- Ideal pH
- 6.0 to 7.0
- Water
- High
- Feeding
- Heavy feeder
Sowing and planting marrows
WhenSow Apr to May indoors; plant out Jun; harvest Aug to Oct
Starting off
Sow indoors 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; harden off and plant out early June. Direct sow under a cloche from late May into soil above 13 °C. Pinch the tip of trailing types at 60 cm to make them branch. Trailing marrows take up a lot of room in the vegetable garden, so give each plant its own corner or choose a bush variety.
Spacing and planting
Bush types 90 cm apart each way, trailing types 1.2 to 1.8 m apart, each on a mound with a 30 cm planting hole filled with compost. Sow or plant 2.5 cm deep. One bush plant will fill a 45 cm pot but yields are small; trailing types are not for containers.
Varieties worth growing
- Tiger Cross F1
- Early, striped bush marrow with resistance to cucumber mosaic virus. The safest choice for most gardens.
- Long Green Bush
- The traditional striped marrow on a compact plant; cut small it doubles as a courgette.
- Long Green Trailing
- The show-bench marrow. Long, heavy fruit on vines that need 1.5 m or more each way.
- Bush Baby F1
- Half-sized marrows of 15 to 20 cm, enough for one meal, on a plant small enough for a tight bed.
Marrows month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do. Use the last stored marrows.
- February
Order seed.
- March
Prepare the planting station: a 30 cm hole filled with compost, soil mounded back on top.
- April
Sow indoors from mid April, one seed on edge per 9 cm pot at 18 to 21 °C.
- May
Sow a second batch as insurance. Harden off at the end of the month. Direct sow under a cloche from late May.
- June
Plant out in the first week. Keep the cloche handy for cold nights. Water in well.
- July
Pinch the tips of trailing types at 60 cm. Start cutting young marrows. Begin potash once fruit sets.
- August
Cut regularly at 20 to 30 cm to keep more coming. Water deeply twice a week.
- September
Leave three or four fruits to ripen for storing. Stop feeding. Raise them off the soil.
- October
Cut the storing marrows before the first frost, cure for 10 days and bring under cover.
- November
Check stored fruit; use any with soft patches first.
- December
Stored marrows keep at 10 to 15 °C until about Christmas. Use them up.
Feeding marrows
Marrows are made of water and whatever is in the planting hole. A rich station, one base dressing and potash while fruit is swelling is all they need; extra nitrogen only makes leaf.
Masses of organic matter plus a high-potassium feed when fruiting.
Feeding plan
Spring, before planting
Garden compost
A bucket or two of compost or well-rotted manure in each 30 cm planting hole.
Planting out, early June
Fruit & Vegetable Fertiliser 4-5-6
100 g/m² forked into the top of the mound and the square metre round it: 100 g per plant.
From first fruit set, every 10 to 14 days until early September
1 to 2 g per litre of water: 10 to 20 g in a 10 litre can, one can per plant.
Only if older leaves yellow between the veins
1 to 2 g per litre of water as a drench, every 2 to 3 weeks until the new leaves stay green.
Signs to watch
Small fruit yellowing and dropping at 5 cm
Poor pollination in cool, wet weather or dry roots, not calcium
Hand-pollinate and water deeply
Yellowing between the veins on older leaves
Magnesium short under high potash
Epsom salts spray
Huge leaves and few female flowers
Excess nitrogen
Switch to a high-potash feed
Pests, diseases and problems
Newly planted marrows eaten down to the stalk
Slugs and snails
Plant out at four or five true leaves, protect each plant with a bottle cloche for two weeks, and go out with a torch on wet evenings.
White powder over the leaves from late July
Powdery mildew, triggered by dry soil at the roots
Soak the root zone twice a week and mulch. Cut off the oldest, worst leaves. The silvery marbling on the leaves of many varieties is normal and is not mildew.
Leaves crumpled and mottled yellow, fruit knobbly and pitted
Cucumber mosaic virus spread by aphids
Remove and bin the plant and wash your hands and knife before touching another. Grow Tiger Cross where the virus has appeared before.
Young fruit rots from the flower end with grey fur
Grey mould starting in the spent flower in cool, wet weather
Twist off faded flowers that cling to the fruit, water at the base in the morning, and remove affected fruit promptly.
A storing marrow goes soft underneath
Contact with wet soil for weeks on end
Slide a tile or board under any fruit you intend to keep and turn it gently once a week so the whole skin sees the sun.
Harvest and rotation
Harvest and storage
Cut for eating fresh at 20 to 30 cm, 10 to 12 weeks from sowing, while a thumbnail still dents the skin; for storing leave until September when the skin is hard and the stem corky. Cut with 5 cm of stalk and cure for 10 days. A plant gives 4 to 6 marrows. Store at 10 to 15 °C in a dry shed for up to 2 months.
Rotation and companions
Rotation: cucurbit group with courgettes, squash and cucumber, 3-year gap; follows legumes or brassicas on a manured bed. Sweetcorn and climbing beans in the 'three sisters' pattern give it shelter and nitrogen.
Good to knowEssentially an overgrown courgette, give it room to ramble and a steady water supply.
Growing marrows in pots
A bush marrow will crop in a 45 cm pot holding about 40 litres, but the plant is thirsty and the yield is two or three fruit, so it is a second-best option. Use multipurpose compost with a third garden compost and the 4-5-6 at 5 g per litre, 200 g for a 40 litre pot. Stand the pot in a saucer in hot weather and water daily. Feed with Sulphate of Potash at 1 to 2 g per litre of water every 10 to 14 days from fruit set. Trailing varieties are not suitable.
Marrows: common questions
Is a marrow just a big courgette?
Botanically yes: both are Cucurbita pepo, and a courgette left on the plant will become a marrow of sorts. Marrow varieties are bred for the job, though, with thicker skins, firmer flesh and better keeping, and they are the ones to grow if marrows are what you want.
When should I pick marrows?
Pick for eating fresh at 20 to 30 cm, while a thumbnail still dents the skin, from late July onwards. For storing, leave the fruit on the plant until September, when the skin is hard and the stalk has dried, and cut before the first frost.
Why do my marrows have lots of flowers but no fruit?
Early in the season the plant produces only male flowers, and fruit follows once female flowers appear with warmer nights. If female flowers, the ones with a tiny marrow behind them, open and then drop, pollination has failed in cold, wet weather: pick a male flower, strip the petals and dab it into each female in the morning.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.