How to grow squashes

With fruits in a wide choice of colours, shapes, sizes and flavours, squashes are eye-catching and attractive plants. They range from large sprawling vines to more compact bushes, so there are types to suit all gardens. These tender plants are best grown from seed sown indoors in spring. 

There are two distinct types of squash – summer and winter. The fruits of summer squashes have a thin skin and (like courgettes) don’t store for long, while winter squashes, such as butternuts, can be stored for several months. Within each of these two types, there are various other categories based on fruit shape, including acorn squashes, patty pans and crooknecks, and there is a vast choice of varieties too, with fruits of various colours, sizes and flavours.

Some varieties are vigorous trailing plants that spread for several metres/yards or can be grown up supports. There are also bush types, which stay reasonably compact, although still take up about a square metre/yard. Smaller varieties can be grown in large containers, but most fare best in the ground. So be sure to choose varieties that suit the amount of growing space you have available.

 Also look for varieties with an RHS Award of Garden Merit (AGM), as these should crop reliably – see our list of AGM fruit and veg.

Watch food writer Nigel Slater exploring the winter squashes grown in RHS trials, with tips on how to cook different varieties.

Squashes like warmth and full sun, in rich, moisture-retentive but not waterlogged soil. They need plenty of space – even the more compact bush varieties can easily spread to 90cm (3ft) across.  

Before planting out or sowing seeds outdoors, prepare the ground where each squash will grow. 

Make a hole about 30cm (1ft) wide and deep, then fill with a mix of soil and home-made compost or well-rotted manure. Scatter a general purpose fertiliser, such as Vitax Q4, over the soil at a rate of two handfuls per square metre/yard.  

Space individual sowing/planting sites at least 90cm (3ft) apart for bush plants and 1.5m (5ft) for trailing plants. 

You can also plant summer squashes in growing bags or large containers filled with multi-purpose or soil-based compost.

Squashes are usually sown indoors in spring, for more reliable germination and to give them a head start, then planted out after the last frost. They can be sown outdoors too, but not until late May or early June. Germination outdoors may be less reliable if temperatures dip and seedlings are vulnerable to slugs and snails, as well as poor weather.

You can plant indoor-raised or bought plants outside after the last frost. But first, harden off to acclimatise them to outdoor conditions. Do this by placing them in a cold frame or under a cloche for a week. Alternatively, stand them outdoors during the day, then bring them in at night for a week, and the following week leave them out in a sheltered spot all day and night. 

Plant young squash plants into prepared ground (see above), taking care not to disturb the roots. Firm plants in gently, then water well. Space bush varieties 90cm (3ft) apart and trailing varieties 1.5m (5ft) apart. Protect from slugs and snails, especially in damp weather.

You can also plant summer squashes in growing bags or large containers in a sunny, open spot. Plant one or two per growing bag or one in a container at least 45cm (18in) wide. Make sure there is plenty of space around the container, to ensure good air circulation and allow plants to spread out their large leaves. Overcrowded conditions can encourage fungal diseases.

If you have plenty of space, trailing types can be left to sprawl over the ground, but if you need to limit their spread, you can train the stems around in a large circle, inserting short canes to hold them in place. You can also simply cut off any stems that stray beyond their bounds.

Trailing squashes can also be trained up supports, but make sure they are sturdy enough to support these vigorous plants and their crop of fruits. You may need to use netting to support individual heavy fruits.

With winter squashes for storing, let the fruits fully ripen on the plant – the riper they are when harvested, the better they’ll keep. Then lay them out in the sun for an additional week or two, either outdoors or in a greenhouse, to harden the skin, which also helps to ensure they store well. Make sure they are safely inside before the first frost.

Then store the fruits in a well-ventilated place at 10–15°C (50–60°F), spaced out so they don’t touch. Depending on the variety, winter squashes should keep for three months or more. Check them regularly for any signs of deterioration or rot.

Squashes are tender plants, so are susceptible to cold and frost. They can be affected by various pests and diseases – see our guide to solving squash problems for more details.