An expert's guide to growing pumpkins
Signalling the start of autumn and seen as a staple of Halloween decor, there are many ways the humble pumpkin can be put to good use, including making a hearty pumpkin soup or a sweet pumpkin pie. If you're considering growing your own, then good news, because growing pumpkins (Cucurbita) is relatively easy and perfect for beginner gardeners.
How to grow pumpkins
May to early June is the prime time to start sowing. You could also plant them later, although they may not be ready for Halloween. 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,' says Hannah. '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 one 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,' Hannah explains.
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,' Hannah explains. 'Mulching around the plants can help retain moisture and suppress weeds. Feed the plants with a high-potash fertiliser 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 18 inches 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. '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,' reveals Angela.
Harvesting and storage
Pick your 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 be 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,' explains 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).'
Powdery mildew and other diseases
'Monitor for diseases like powdery mildew and practice good garden hygiene to prevent them,' says Hannah. Powdery mildew is a fungal disease that appears as white spots on the leaves. Often a result of poor airflow, if you notice powdery mildew appearing, simply remove and destroy infected leaves to control its spread.
Dense foliage on the vines, crowded plants, and those grown in shady locations can cause the infection to spread rapidly. Keep the roots evenly watered and inspect your plant weekly.
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.
Other pests
You'll also want to keep an eye open for pests, like slugs, snails, and aphids. 'Use organic methods such as hand-picking, barriers, or natural predators to control infestations,' explains Hannah.
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