How to grow marrows

Marrow seeds are readily available from garden centres and online seed stockists. In spring, you may also find young marrow plants on sale in garden centres and online. These are useful if you don’t have the time or space to grow from seed, but the choice of varieties may be limited. If you buy after the last frost, they can usually be planted out straight away – although do check with the seller to make sure they have been hardened off.

For a longer cropping season or more reliable results in colder regions, start marrows off indoors from mid- to late April. 
 
Sow the seeds into 7.5cm (3in) pots or a modular tray filled with moist peat-free seed compost. Position the seed on its side, 1.5cm (½in) deep, sowing one per pot/module, to minimise root disturbance when planting out later. Water in, then keep at 18–21°C (65–70°F) in a heated propagator. Alternatively, place on a warm sunny windowsill and cover with clear plastic bags until the

A seedling is a young plant grown from seed.

You can sow marrow seeds outdoors in late May or early June. If possible, warm the soil for a couple of weeks ahead of sowing, especially in cooler locations, by covering the ground with cloches or plastic-free fleece. The soil should be at least 13°C (56°F) for successful germination.

Sow two or three seeds in the centre of each prepared site, 2.5cm (1in) deep, then water well. Cover with cloches or plastic-free fleece, and leave in place for as long as possible after germination. If more than one seed germinates per sowing site, remove the smaller, weaker

A seedling is a young plant grown from seed.

Germination is the process by which a seed develops into a new plant. It starts with the seed coat absorbing water, expanding and splitting, which allows oxygen and water into the seed so its food reserves can be broken down and used by the embryo for growth. The first root (called the radicle) pushes into the soil to anchor the new plant in place and start absorbing water and nutrients. The first shoot (called the plumule) then grows upwards, out of the soil, towards the light.

Germination

Marrows generally crop best in the ground, but compact or bush varieties can also be grown in a large container. Just bear in mind that plants will need regular watering and feeding to swell the large fruits. Also make sure there is plenty of space around the outside of the container, so the marrow plant can spread out its large leaves. Overcrowding and poor air circulation encourage fungal diseases.

Choose a container that’s at least 45cm (18in) wide, fill it with peat-free soil-based or multi-purpose compost, then plant one young marrow plant in the centre. 

Marrows need regular and generous watering, especially when flowering and fruiting, and when growing in containers. Aim to keep the soil or potting

Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

Use rainwater from a butt if possible, and when you water, try not to wet the leaves, as this can encourage fungal diseases such as powdery mildew. For more water-wise advice, see our guides below.

Cover the ground around marrow plants with a thick layer of

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.

Marrows growing in the ground don’t generally need feeding, unless the soil is very poor. But if you want particularly large fruits for exhibition, or are growing marrows in containers, then it’s worth feeding regularly – apply a high potassium organic liquid fertiliser, such as tomato feed, every 10–14 days once the first fruits start to swell.