Pumpkins are easy and fun to grow – just give them a sunny position, plenty of water and shelter from cold winds. One of the finest sights of autumn is colourful pumpkins ripening in the sun. As well as making great Halloween decorations, the fruits can be used to make hearty soup and are delicious roasted.
Jobs to do now
- Sow seed outdoors under protection
- Harden off
Month by month
Pumpkins are best grown from seed indoors, but can also be sown later outdoors in a sheltered spot.
For earlier crops or in cold regions, sow seeds indoors in 7.5cm (3in) pots from mid- to late April. Sow the flat seeds on their side, 1cm (½in) deep, and keep at 18–21°C (65–70°F).
If you don’t have the space to raise pumpkin seedlings indoors, you can often buy young plants in garden centres in spring.
You can also sow seeds directly outdoors where you want your plants to grow. Sow two or three seeds per planting hole, 3cm (1in) deep, in late May or early June. Cover with cloches, jars or plastic sheeting. Leave this in place for two weeks, or as long as possible, after germination. Thin the seedlings, leaving only the strongest one to grown on.
Pumpkins need a warm, sunny position, shelter from cold winds and moisture-retentive soil.
In late May, start hardening off indoor-raised plants, to acclimatise them to outdoor conditions. Do this by moving them into a coldframe for a week. If you don’t have a coldframe, move plants outdoors during the day, then bring them in at night for a week. The following week, leave them out in a sheltered spot all day and night. Plant them out in early June, when all risk of frost has passed.
Before transplanting indoor-raised plants or sowing seeds outdoors, prepare the planting site by making a hole about a spade’s depth and width. Backfill with a mixture of garden compost or well-rotted manure and soil. Sprinkle a general purpose fertiliser, such as Vitax Q4 over the soil at a rate of two handfuls per square metre/yard. Space these planting or sowing sites 1.8m (6ft) apart.
You can also plant pumpkins in growing bags or large containers (at least 45cm/18in wide), but bear in mind that they’ll need regular and generous watering. Plant one or two per growing bag, or one per container.
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 can lead to rotting.
Feed every 10–14 days with a high potassium liquid fertiliser, such as tomato feed, once the first fruits start to swell.
Support developing fruits on a piece of tile or glass, to keep them off the damp soil.
Let the pumpkins mature and colour up on the plant before picking in autumn. They can be used straight away or stored for use in winter.
Harvest before the first frost, or protect the fruits using straw, fleece or cardboard, as frosted fruit can’t be stored.
If storing, place the pumpkins in the sun for a week, either outdoors or in a greenhouse, to harden (or cure) the skins. This helps to ensure they keep well.
Store your pumpkins in a well-ventilated place indoors at 10–15°C (50–60°F).
Depending on the variety, pumpkins should keep for at least three months, and up to six months in ideal conditions.
Appears as a white powdery deposit over the leaf surface and leaves become stunted and shrivel.
Keep the soil moist and grow in cooler locations.
No fruit, or fruit rotting when very small
This is a physiological problem, caused by the growing conditions, not a pest or disease. It is a problem when the weather in early summer is cool and this causes inadequate pollination.
This is usually a temporary problem and once the weather starts to improve, so will pollination. You can try to hand-pollinate plants yourself by removing a male flower (no swelling at their base) and brushing the central parts against the centre of a female flower (female flowers have a swelling at the base – this is the beginning of the fruit). But this is a bit of a hassle, and normally the plant will correct this problem itself.
A usually grey, fuzzy fungal growth which can begin as pale or discoloured patches. Grey mould ( botrytis) is a common disease especially in damp or humid conditions. Spores enter plants via damaged tissue, wounds or open flowers. Mould can also damage ripening fruit such as strawberries. Black resting spores survive over winter.
Remove damaged plant parts before they can become infected. Cut out infected areas into healthy tissue and clear up infected debris. In greenhouses, reduce humidity by ventilating and avoid overcrowding of young plants and seedlings.
Why not try making pumpkin cake? You can use pretty much any kind of pumpkin, and it’s a delicious, autumnal alternative to carrot cake.
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.