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.
Squashes are usually grown in the ground, as they need plenty of space, but compact varieties of summer squash can be grown in large containers. Trailing types can be allowed to sprawl over the ground if you have plenty of space or can be trained up sturdy supports.
There are many different types and varieties of squash, but they’re broadly classified as either winter or summer squashes. Summer squashes are soft skinned, best picked young and used straight away, while winter squashes are usually grown to maturity, then dried off and stored for use into winter. Pumpkins are a type of winter squash.
Month by Month
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.
What and where to buy
You’ll find a wide choice of varieties as seed in garden centres and from online retailers. Young plants may also be sold in spring and early summer, ready for planting out – ideal if you only want one or two, or don’t have space indoors to start them off yourself. However, the choice of varieties may be very limited.
Squashes — summer
Preparing the Ground
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.
From mid- to late April, sow the flat seeds on their side, 13mm (½in) deep, into 7.5cm (3in) pot of multi-purpose compost. Sow only one seed per pot, to minimise root disturbance when planting out later.
Keep at 18–21°C (65–70°F) in a heated propagator or on a warm windowsill. Cover with a clear lid or polythene bag to hold in moisture, until the seedlings appear. Water the seedlings regularly and keep in good light, until ready to plant out after the last frost – see Planting out, below.
Seeds can be sown outdoors, in the site where they are to grow, in late May or early June. Prepare your sowing sites as detailed above, spacing each one 90cm (3ft) apart for bush varieties and 1.5m (5ft) for trailing varieties.
You can also warm the soil for a couple of weeks ahead of sowing by covering the ground with polythene sheeting or cloches.
Sow two or three seeds into each prepared sowing site, 2.5cm (1in) deep, then cover with cloches or plastic sheeting. Leave these in place for as long as possible after germination. If more than one seedling germinates in each growing site, thin out to leave just the strongest one.
Keep the seedlings well watered and protect from slugs and snails, especially in damp conditions.
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.
Squashes are thirsty plants, especially when fruiting, so aim to keep the soil or compost constantly moist. Regular watering also helps to deter powdery mildew, but take care not to wet the leaves – water around the plants, not over them.
To make this easier, sink a 15cm (6in) pot alongside each plant, then water into it. This ensures the water goes down to the roots and doesn’t sit around the neck of the plant, which can lead to rotting.
After planting, cover the soil surface with a thick layer of mulch, such as garden compost, to help hold in moisture. Leave a gap around the base of the plant stem though, to keep dampness away, which could lead to rotting.
Once the first fruits start to swell, feed squash plants every 10 to 14 days with a high potassium liquid fertiliser, such as tomato feed.
Ripening winter squashes
With winter squashes, place a tile, brick or wooden board beneath larger fruits to lift them off the damp soil – this prevents rotting and damage by slugs and snails. Also make sure they are exposed to full sun, to aid ripening.
Pruning and Training
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.
Harvest their fruits when small and tasty, with a soft skin. Regular picking encourages further fruits to form.
Winter squashes can also be harvested and used straight away. But they can also be ripened then stored for many months, for use well into winter – see Storing, below. Keep them on the plant as long as possible to develop the best flavour, but pick before the first frost.
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.
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