How to grow pumpkins: a step-by-step guide
Are you wondering how to grow pumpkins? Whether you're using them for carving or to decorate your autumn front door display, here's everything you need to know about growing pumpkins in your outdoor space.
Pumpkins, (Cucurbita maxima) are easy to grow, making them the perfect project for novices. As well as being used at Halloween, small pumpkins can be utilised by gardeners either as a bird feeder or a nest simply by hollowing them out, leaving to dry, painting with a few coats of varnish and attaching a loop of string.
Additionally, the seeds of a pumpkin can be dried, painted with acrylics and used by children to make pictures or jewellery. And you'll no doubt already know that growing pumpkins in your garden can be used to make delicious soups and pies, or simply roasted with olive oil and herbs.
How to grow pumpkins
May to early June is the prime time to start sowing. Angela Slater, gardening expert at Hayes Garden World, says once the soil temperature has reached 65F, you’ll want to sow outdoors and then cover with a cloche.
Here's how you can grow and harvest pumpkins in time for Halloween:
1. Choose the right variety: 'Select pumpkin varieties that thrive in the UK climate. Some popular choices include 'Jack-o'-Lantern,' 'Atlantic Giant,' and 'Crown Prince'', Hannah Rowson, Assistant Garden Centre Manager at J. Parker's, tells House Beautiful UK.
2. Timing is crucial: 'Start your seeds indoors in late April to early May. Pumpkins need a long growing season, so giving them a head start will help ensure they mature before the first frost.'
3. Prepare the seeds: Next, you'll want to prepare the pumpkin seeds by soaking them in warm water for a few hours. 'This helps to soften the seed coat and can speed up germination.'
4. Planting seeds indoors: 'Use small pots or seed trays filled with a good quality, well-draining compost. Plant the seeds about 1 inch deep, with the pointed end facing down. Keep the soil moist but not waterlogged, and place the pots in a warm, sunny spot. A temperature of around 20-25°C is ideal for germination.'
5. Transplanting outdoors: Once your seedlings have developed a few leaves, it's time to move them outdoors. You'll need to give your pumpkin plenty of space to grow, ideally in well-draining moisture-retentive soil in full sun, but sheltered from strong winds. 'Pumpkins are heavy feeders, so enrich the soil with plenty of compost or well-rotted manure,' says Hannah.
6. Watering and feeding: 'Pumpkins need consistent moisture, especially during hot, dry spells. Water deeply and regularly, ensuring the soil stays moist but not waterlogged. Mulching around the plants can help retain moisture and suppress weeds. Feed the plants with a high-potash fertilizer every few weeks to encourage healthy growth and fruit development.'
Can pumpkins be grown in containers?
Yes, pumpkins can be grown in containers, but they must be at least 18ins deep and wide.
Angela says you'll need a good quality peat-free compost, a forkful of well-rotted manure in the bottom and a handful of Growmore added to the compost. But, 'the problem with growing in a container is you have to be really vigilant about watering during hot spells; when they are in full growth they could need watering three times a day', Angela warns.
Feeding and aftercare
Once the first fruits start to appear, feed every 10 days with a high potash tomato fertiliser to encourage the formation of flowers and fruit.
You should place fruits onto a bed of straw or piece of tile to keep them off damp soil and prevent them from becoming black on one side. They need to be kept well-watered. 'If you want to produce prize-winning giants, take off all the small fruits leaving just one per plant,' Angela adds.
Harvesting and storage
You should pick the pumpkins in September or October when they have stopped growing and have turned bright orange. Place them in a hot sunny spot for 10-14 days and allow the skin to bake and harden. This means they will be less likely to rot, which is important if you intend to store them over winter.
When storing your pumpkins, you'll need to place them in a frost-free spot over winter and they will keep for three to six months.
'Pumpkins are ready to harvest when they have reached their full size, the skin is hard, and they have developed a deep, rich colour. Cut the pumpkins from the vine with a sharp knife, leaving a few inches of stem attached. This helps to prolong their storage life,' says Hannah.
Growing pumpkins: potential problems
What if no fruit appears? This could happen due to poor pollination when the weather is too cool.
'Pumpkins rely on bees and other insects for pollination. Plant pollinator-friendly plants around your pumpkins to attract pollinators to your garden,' adds Hannah. 'If pollinator activity is low, you may need to hand-pollinate the flowers. Use a small brush to transfer pollen from the male flowers (which have a thin stem) to the female flowers (which have a small swelling at the base).'
Another problem is powdery mildew which is due to poor airflow and a stressed plant; for example, allowing it to dry out. Angela also advises keeping a lookout for botrytis (grey mould) which is a condition of damp humid conditions. If this occurs, you should cut out any infected parts and burn, making sure you also clear up any fallen infected material.
You'll also want to keep an eye open for pests and diseases, like slugs, snails, and aphids. 'Use organic methods such as hand-picking, barriers, or natural predators to control infestations. Monitor for diseases like powdery mildew and practice good garden hygiene to prevent them,' continues Hannah.
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