Sow
- Sow indoors:
mid- to late April into May
- Sow outdoors:
late May to early June, after frost and once soil is at least 13°C
Marrows
This Allotment Pro editorial draft summarises the cited RHS guide. Check the source and adjust cultivation decisions for local conditions.RHS source guide
Month by month
Plant
- Plant out:
early summer after hardening off and after the last frost
Harvest
- Harvest:
mid-summer into autumn, bringing the final fruits indoors before frost
1 - Getting Started
Marrows are tender, vigorous vegetables grown for large fruits that can be cooked soon after harvest or ripened until their skins harden for storage. They need warmth, full sun, generous water and plenty of room. In good summer conditions, a plant can spread rapidly and swell sizeable fruits in a short time.
Marrows and courgettes are forms of the same botanical species, *Cucurbita pepo*. Any courgette can become marrow sized if left unpicked, but dedicated marrow cultivars are selected to crop well at a larger size and to store more successfully. Most traditional fruits are green with pale lengthwise stripes, although yellow-skinned cultivars also exist.
Choose between bush types, which are relatively compact, and trailing forms that may extend for several metres. Even a bush marrow is a large plant with broad, prickly leaves, so plan its position before sowing. Compact cultivars can grow in containers, but crops usually perform best in rich prepared ground.
2 - Choosing What To Grow
Match the cultivar to the available space. Bush forms are suited to smaller plots and very large containers, while trailing types need open ground and room to roam. RHS Award of Garden Merit cultivars have performed reliably in trials. Young plants are sold in spring, but seed offers the widest choice and avoids transporting an already vigorous root system.
Recommended varieties
‘Badger Cross’ AGM
A neat compact British-bred bush marrow producing high yields of small, well-shaped fruits with distinctive dark- and light-green stripes. This F1 hybrid has excellent resistance to cucumber mosaic virus.
‘Bush Baby’
A compact bush variety suitable for large containers and smaller gardens where a trailing marrow would take too much space.
‘Tiger Cross’ AGM
An early-cropping bush marrow bearing green-and-cream striped fruits. It is a modern British-bred F1 hybrid.
‘Long Green Trailing’
A traditional trailing cultivar for a spacious plot, producing large dark-green fruits marked with lengthwise stripes.
3 - Preparing The Ground
Choose the warmest sunny site available. Space bush plants at least 90cm apart and trailing cultivars about 1.5m apart. Keep the surrounding area open so large leaves can spread and air can circulate, reducing the humid conditions in which fungal diseases thrive.
Prepare each planting station several weeks ahead if possible. Dig in plenty of homemade garden compost or well-rotted manure over an area roughly the depth and width of a spade blade, then allow the soil to settle. In a no-dig bed, apply organic matter as a surface mulch and sow or plant through it.
For container growing, choose a compact bush cultivar and a pot at least 45cm wide. Fill it with peat-free soil-based or multi-purpose compost and plant one marrow in the centre. Leave substantial free space around the container for foliage and expect to water and feed much more often than a plant in open ground.
4 - Sowing
Marrow seeds germinate readily in warmth. Starting indoors gives a longer season and keeps vulnerable seedlings away from slugs and snails until conditions improve. Direct sowing is possible after the last frost once the soil is reliably warm.
Sowing indoors
Start from mid- to late April. Fill 7.5cm pots or a modular tray with moist peat-free seed compost. Place one seed on its side in each pot or module, 1.5cm deep, to reduce the risk of rotting and minimise later root disturbance.
Water and keep at 18–21°C in a heated propagator, or use a warm sunny windowsill covered with a clear bag until seedlings appear. Remove covers promptly after germination. Keep plants in a bright warm place, water regularly and do not move them outdoors until frost risk has passed.
Sowing outdoors
Sow outside in late May or early June. In a cool district, warm prepared stations for about two weeks beneath cloches or plastic-free fleece. The soil should reach at least 13°C for dependable germination.
At each station, sow two or three seeds 2.5cm deep and water well. Replace the cloche or fleece and retain protection as long as conditions require. Once seedlings establish, remove the smaller plants to leave only the strongest at each station. Outdoor sowings usually crop later and need careful slug and snail protection.
5 - Planting
Harden off indoor-raised or bought young plants gradually, then plant after the last frost in early summer once the soil has warmed. Prepare the stations first. Ease each root ball from its pot without breaking it, set it at the same depth, firm gently and water thoroughly.
Protect newly planted marrows from slugs, snails, cold winds and any unexpected low temperature. Avoid packing plants between other large crops: their broad foliage needs light and airflow, and overcrowding makes watering, pollination and harvesting more difficult.
Set one plant in the centre of each 45cm or larger container. Place the pot in full sun where the leaves can spread without obstructing paths. A container-grown marrow needs close attention because its large leaf area and expanding fruits exhaust water rapidly.
6 - Plant Care
Watering
Keep soil or potting compost consistently moist, especially while plants flower and fruits swell. During hot spells, daily watering may be necessary, particularly in containers. Water early in the morning or in the evening and use collected rainwater where possible.
Direct water onto the soil rather than leaves, since wet foliage encourages powdery mildew and other fungal problems. Sinking a 15cm pot beside a ground-grown plant creates a simple reservoir: pour water into it so moisture reaches the roots without sitting against the crown, where persistent damp can cause rot.
Mulching and feeding
Apply a thick mulch of garden compost or well-rotted manure to hold soil moisture and suppress weeds, leaving a clear gap around the stem base. Ground-grown plants in fertile prepared soil rarely need extra feeding. Container crops, plants on poor soil and exhibition fruits benefit from a high-potassium organic liquid feed every 10–14 days once the first fruits begin to swell.
Looking after fruits
Slide a tile or wooden board beneath each developing marrow to keep it off damp soil. If a fruit is intended for storage, expose it to sun and turn it carefully from time to time so the underside ripens evenly. For a single giant exhibition marrow, remove competing young fruits and concentrate watering and feeding on the one retained specimen.
No routine pruning is required. Remove only tatty leaves or foliage affected by powdery mildew. This improves airflow and lets more sun reach fruits whose skins need to harden.
7 - Harvesting And Storing
Cut marrows from mid-summer once they reach the size needed. Fruits 20–30cm long are tender enough for immediate cooking. Use a knife or secateurs to sever the stalk rather than twisting and damaging the plant. The flowers are edible too.
Harvesting regularly encourages further fruits, and growth can be extremely quick in warm damp weather. Search beneath the large leaves often. Later in the season, leave selected fruits to reach full size and ripen for storage, but bring every remaining marrow inside before frost.
A storage marrow needs a fully mature, hard skin. Ripen it in sun on the plant, then place it in a cool, dark, dry and frost-free location such as a garage. Properly cured fruits may keep for one or two months. Inspect them regularly and remove any specimen that softens, leaks or shows rot.
8 - Problem Solving
Cold and frost can damage or kill tender plants. Cool weather in early summer may also prevent fruit set or cause very young fruits to rot because pollination is poor. This usually improves as temperatures rise and insect activity increases.
Protect seedlings from slugs and snails, keep foliage dry when watering and maintain generous spacing. Grey mould and powdery mildew are more likely where leaves remain damp and air circulation is restricted. Bitter fruits may contain harmful levels of cucurbitacins: do not eat a bitter marrow or feed it to pets.
Common problems
Courgette, marrow, pumpkin and squash problems
Poor fruit set, rotting young fruits, distorted growth, mildew and pest damage affect several cucurbit crops. Correct identification helps distinguish temporary pollination failure from disease or cultural stress.
Problem sourceGrey mould
Soft brown decay followed by fuzzy grey fungal growth develops in cool damp conditions. Remove affected tissue, improve airflow and keep water off leaves and fruit surfaces.
Problem source