Pumpkins are easy and fun to grow – just give them a warm sunny site, plenty of water and shelter from cold winds. By autumn, you’ll have colourful pumpkins to make into Halloween decorations or to store for use in winter – they’re delicious roasted or turned into hearty soups.
Pumpkins are a type of winter squash, traditionally with large, rounded, orange fruits. They are usually grown from seed sown indoors in spring, then planted out after the last frost, but can also be sown outdoors once the soil warms up.
Pumpkins like a warm, sunny site, with fertile soil and lots of rain or regular watering. They need a long, hot growing season, as the fruits are usually grown to maturity and must ripen fully in order to store well for use in winter. Most varieties form large sprawling plants that require plenty of space, although more compact bush varieties, usually with small fruits, are also available.
As well as being carved into Halloween lanterns, pumpkins can be used in a wide range of both savoury and sweet dishes, or can simply be roasted. You can also roast the seeds of some varieties, to eat as a healthy snack.
Month by Month
There are many varieties of traditional orange pumpkins, with various sizes of fruit, from cricket ball up to beach ball size, and potentially larger. The small to medium fruits are generally more convenient for eating, the larger ones are great for carving into impressive Halloween lanterns, and the giant ones are ideal for entering into shows and competitions.
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 at least a square metre/yard. Smaller varieties can potentially 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 grow and crop reliably – see ‘squashes – winter’ in our list of AGM fruit and veg.
What and where to buy
You’ll find many varieties as seed in garden centres and from online retailers. Young plants may also be available in spring and early summer – ideal if you only want one or two plants, or don’t have space indoors to sow them. However, the choice of varieties may be limited.
Preparing the Ground
Pumpkins are best grown from seed indoors in mid-spring, but can also be sown a month or so later outdoors. Indoor sowing offers more reliable results and gives plants a head start and a longer growing season. This is especially useful in colder areas. However, you do need somewhere warm and bright to keep the plants for about six weeks, until they can be moved outside.
Pumpkins need a warm, sunny growing site, with shelter from cold winds and soil that is fertile and moisture retentive but not waterlogged. They generally grow less well in cooler sites. These vigorous plants need plenty of space too – even the more compact bush varieties can easily reach 90cm (3ft) across.
It’s worth taking the time to prepare the ground well, ahead of planting or sowing outdoors, to ensure your pumpkins thrive.
Make a hole about 30cm (1ft) wide and deep, then fill with a mix of soil and home-made compost or well-rotted manure. Add a general purpose fertiliser, such as Vitax Q4, scattering two handfuls per square metre/yard.
Space the individual sowing/planting sites at least 90cm (3ft) apart for bush plants and 1.5m (5ft) for trailing plants.
You can also plant compact varieties in growing bags or large containers filled with multi-purpose or soil-based compost.
Keep the pots at 18–21°C (65–70°F) in a heated propagator or place them on a warm, bright windowsill and cover with a clear polythene bag to hold in moisture. Remove once the seeds germinate.
Water the seedlings regularly and keep them in bright light until ready to plant out after the last frost – see Planting out, below.
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 site, 3cm (1in) deep. Cover with a cloche or plastic sheeting, and leave in place for two weeks or more after germination.
Water the seedlings regularly and protect from slugs and snails, especially in damp conditions.
If more than one seed germinates in each spot, remove the weaker ones to leave only the strongest one to grown on.
You can plant indoor-raised or bought plants outside after the last frost. But first, harden off plants to acclimatise them to outdoor conditions. Either place them in a cold frame or under a cloche for a week, or stand them outdoors during the day and bring them in at night for a week, then for a further week keep them 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 them in gently and water well. Space bush varieties 90cm (3ft) apart and trailing varieties 1.5m (5ft) apart. Protect young plants from slugs and snails, especially in damp weather.
You can also plant very compact bush varieties 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.
Pumpkins need plenty of water. To make watering easier, sink a 15cm (6in) pot alongside each plant. Water into this to ensure the water goes down to the roots and doesn’t sit around the neck of the plant, which could cause rotting.
After planting, cover the soil with a thick mulch of garden compost to help hold in moisture. But leave a gap around the base of the plant stem, to keep dampness away, which could lead to rotting.
When the first fruits start to form, begin feeding every 10 to 14 days with a high potassium liquid fertiliser, such as tomato feed.
Looking after fruits
Support developing fruits on a tile, brick or piece of wood, to keep them off the damp soil, which could cause rotting or attract slugs and snails.
Also make sure they are exposed to full sun, to aid ripening – pumpkins must be fully ripened to store well.
Growing larger fruits
If you want to grow large fruits, then limit the number to just two or three per plant, and for giant pumpkins leave just one, removing any further flowers or fruit that start to form. All the plant’s energy will then be directed into swelling its remaining fruit.
Pruning and Training
If you have plenty of space, plants 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 types can also be trained up supports, but make sure they are sturdy enough to support these large, vigorous plants and their fruits. You may need to use netting to support the fruits individually. Larger-fruited varieties are best grown flat on the ground.
Pumpkins can be used straight away or stored for use in winter. Let the pumpkins mature and colour up on the plant before harvesting in autumn. Keep them on the plant for as long as possible, but harvest before the first frost, or protect the fruits using straw, fleece or cardboard, as frosted pumpkins can’t be stored.
Prepare fruits for storing by laying them out in the sun for a week to 10 days, either outdoors or in a greenhouse or cold frame, to harden (or cure) the skins. This helps to ensure they keep well.
Store your fully ripened pumpkins in a well-ventilated place at 10–15°C (50–60°F), making sure the fruits don’t touch.
Depending on the variety, pumpkins should keep for at least three months, and up to six in ideal conditions. Check them regularly for signs of deterioration or rot.
Pumpkins are tender, so must be protected from frost and cold. They can also be affected by several pests and diseases – find out what to look out for in our guide to solving pumpkin problems.
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