Pumpkins are a cultivar of squash and are grown for a multitude of reasons. They’re popular through autumn especially when they are carved and put outside front doors invite trick-or-treaters. So how do you grow pumpkins in the garden?
Pumpkins have great nutritional value, high in fibre, beta-carotene, and they have more potassium than a banana. Remember to also save the seed to roast – not only are they a delicious healthy snack they are also rich in iron.
Planting them ready for harvests around Halloween means they can be used in a variety of autumnal recipes like pumpkin pies, soups, and even pumpkin spiced scones.
You’ll know when they’re ready to harvest because they’ll have the classic, vibrant orange colouring and the pumpkins will sound hollow when they’re tapped.
Pumpkin seeds can be sown indoors in peat-free seed compost and raised to seedlings when they can be planted out, or sow outdoors from May for ease. Based on the UK climate, the latest time so sow them outdoors is June. You’ll want to pick a sunny but sheltered spot for them to grow, with some slow-release fertiliser or organic matter dug into the ground beforehand.
When planting out, they need space. Big spaces mean big pumpkins!
The surrounding soil be mulched with garden compost or even grass clippings to retain moisture, provide more nutrients, and suppress weeds. This technique will also work with other vining crops like beans, cucumbers, tomatoes, or in warmer parts of the UK, melons.
Regardless of space it’s a good idea to use a trellis when growing pumpkins. This will help reduce disease and encourage good air flow. Start to train your pumpkins as soon as they start sprawling. Sprawling vines have very long stems but unlike grapes do not have means to attach to surface. This is why you train the vines which avoids the vines growing into mounds. You can use a pair of tights or old t-shirts with string on corners to help support fruits as they start to grow.
Caring for pumpkins
You cannot underestimate how hungry and thirsty these plants are, so keeping them regularly watered but be consistent. Feed with a liquid fertiliser that’s high in potassium. Tomato feed is ideal because it will help the fruits to grow their best. When sprawling pumpkins produce small rooting roots. These roots help anchor the plant and get more nutrients into it.
Cover the roots with fresh peat free compost to aid moisture retention and protection. If the vine becomes diseased these anchors will draw nutrients the plant needs.
Pests and disease
When tending to the pumpkin, check the leaves regularly for any eggs on the underside. It is likely that these are squash bugs. Established plants can usually cope with these insects, but younger tender plants can be killed off by them.
If you find any eggs, remove them from the leaf and dispose of them. For hatched insects, you can create a squash bug trap by laying cardboard or newspaper around the plant. Overnight the bugs will seek shelter under the paper, and you can pick them out. If you control the foliage too, birds can help with the removal of unwanted insects.
Young pumpkin plants are vulnerable to slugs and snails, so covering with a cloche is ideal to ward off these garden pests.
Aphids can affect weak, young plants, but these can be washed off and removed. Keeping the plant well-watered and strong will help fend off aphids in the first place.
Mildew can also be an issue later in the season and this is when you have too much foliage reducing flow of air. Remove some leaves to allow birds and pollinators to access the area to eat pests and their eggs. However, due to the timing, the fruits will have likely developed and be ripening so this could impact the growth and taste of the pumpkins.
Pumpkins have separate male and female flowers. In good conditions bees and other pollinators will do their magic, but if we are experiencing a colder or wet summer you may need to offer a helping hand.
Do this by removing a male flower and inserting it into the female flower to transfer pollen from one to the other. The males will usually have many stamens rich with pollen while the females only have pistils.
The female flowers have what looks like a small fruit between the stem and the flower. On the other hand, male flowers tend to be shorter and don’t have this small fruit-like section and most of the time bloom in clusters.
If you want the plant to focus on producing a smaller number of fruits, you can pinch out a female flower, so the energy is focused into the existing fruit.
Also, it’s not essential but if you’re short on space, the vines can be trimmed which can lead to larger fruits. This can also make the plants easier to maintain, stop them smothering other plants, whilst also increasing air circulation reducing disease.
Growing pumpkins in a compost heap
Amazingly, you can also grow pumpkins in a compost heap. Plant them on the surface of the heap and let the nutrients within the heap feed the plant.
If you do go with this approach, bear in mind that pumpkins are heavy feeders. Although you can grow pumpkins from compost heaps, they are thirsty plants, made up of 90% water and nutrient hungry – therefore this can take away essential nutrients and reduce the nutrient value of the compost as whole.
If compost heaps conditions are too wet which is a big pumpkin requirement, water will fill the pore space needed for air movement, and anaerobic conditions can result. If conditions are too dry, the decomposition rate will slow down. It’s a fun thing to try, but if you want to have a nutrient rich heap for your garden, then perhaps stick to planting pumpkins in the ground instead.
So, how do you know when the pumpkin is ready to harvest? Colour is a good indicator, but it is not the only one.
Try tapping the pumpkin to hear if it sounds hollow. This is great indicator of ripeness. The skin is often harder – press your finger against the skin and if it dents but doesn’t puncture the fruit then the pumpkin is ready.
Finally, the stem above the pumpkin should be turn hard another indication that the pumpkin is ready.
Do not snap pumpkin off, use secateurs for a clean cut.
It is sensible to wipe the pumpkin down with 10% bleach solution. This will kill any organisms on the skin and prevent it from rotting too soon. The solution will evaporate in the few hours, so it won’t be harmful when you are ready to eat it.
Storing your harvest
When you are getting ready to store pumpkins try the following:
- Place a board underneath the ripe fruit to prevent discolouration and from any hungry slugs.
- Don’t use the stalk as a handle as this can damage the fruit.
- Cure the fruit outdoors in sunlight for 7 to 10 days. Cover them at night using cardboard or straw to protect against frost. Or use your greenhouse, polytunnel or cold frame.
- Store the fruits in a well-ventilated position at a temperature under 15 degrees centigrade or 60 degrees Fahrenheit. Keep an eye out for rot and remove any fruit that are affected straight away.
- Fruits can be kept in this way for up to months.
And with your fantastic fruit ready, you can enjoy a delicious autumn and winter bounty of this delicious and healthy fruit. Grow pumpkins in the garden to add an assortment of dishes to your dinner table, or for the classic carved fruits for Halloween. They are incredibly rewarding to grow, and the kids will love to see the process too.
David Domoney is a Chartered Horticulturalist, Broadcaster, and Author. David has worked with a number of the UK’s leading garden retailers as a plant buyer and strategic consultant. With more than 30 years experience, in horticulture, David is as passionate about plants now as he was when he bought his first plant at a village fete.
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