How to grow pumpkins and winter squash

Give pumpkins and squash a rich soil, a warm start after frost, and consistent water — then stand back. They'll romp away and produce a harvest that sees you through autumn and deep into winter.

Pumpkins, winter squash and the difference between them

The terms "pumpkin" and "winter squash" are used loosely and often interchangeably, but they refer to a group of fruits from the Cucurbita family — typically Cucurbita maxima, C. pepo and C. moschata. What they share is a hard, mature skin that protects dense, sweet flesh and allows them to be stored for months rather than days. This distinguishes them from summer squash and courgettes, which are harvested young and soft and don't store for long.

• Pumpkins are generally rounder, orange-skinned types — both decorative and edible. Classic varieties include 'Jack o' Lantern' types (large, less flavourful), 'Hokkaido' / 'Red Kuri' (smaller, excellent for eating), and 'Atlantic Giant' for the very committed grower who wants something colossal.
• Winter squash come in extraordinary variety: 'Butternut' (C. moschata — long, fawn-skinned, sweet flesh, excellent keeper), 'Crown Prince' (C. maxima — slate-blue skin, firm orange flesh, remarkable storage), 'Delicata' (small, striped, cooks quickly), 'Hubbard' types (large, warty, very long-keeping), and 'Spaghetti Squash' (flesh separates into noodle-like strands when cooked).

For kitchen use and storage, varieties from the Cucurbita maxima and C. moschata groups are generally superior in flavour to most pumpkins grown primarily for their appearance. If you have the space and want a dual-purpose crop, 'Crown Prince', 'Red Kuri' or 'Butternut' are all excellent starting points.

Space requirements and vertical training

Pumpkins and winter squash are genuinely space-hungry plants. A traditional trailing variety allowed to sprawl naturally will occupy a large footprint — sometimes 2–3 metres of ground per plant in each direction. This is worth knowing before you commit a large section of your garden, and it's why planning matters more with cucurbits than with most other vegetables.

• Trailing varieties grown to sprawl: allow at least 1.5–2 m between plants, and ideally more. Many growers train the main vine in one direction (rather than letting it sprawl randomly) by gently redirecting it as it grows. This makes the garden more navigable and easier to maintain.
• Vertical training: trailing squash can be trained up a very sturdy trellis, arch or fence, significantly reducing the ground area they occupy. The support must be very robust — pumpkins and large squash are heavy, and a weak trellis will collapse under the weight of the vines and fruit. Wire mesh, heavy timber frames or metal arches are all suitable.
• Supporting fruits vertically grown: fruits growing off the ground must be supported individually as they swell. Use old tights, net bags or squares of garden fabric tied into a hammock-style sling, attached to the support structure. Check and adjust as the fruit grows heavier.
• Compact and bush varieties: some varieties — including many labelled "bush" or "compact" on the seed packet — have shorter main vines and are better suited to smaller gardens. 'Patio Star', 'Bush Buttercup' and some F1 hybrids are compact enough for a raised bed. They produce smaller but perfectly useable fruits.

Soil and compost preparation

Pumpkins and squash are among the most nutrient-hungry crops in the vegetable garden. They evolved in conditions of rich, disturbed soil high in organic matter — and they grow best when you replicate that. Preparing the soil generously before planting makes a dramatic difference to the size, number and quality of fruits.

The classic approach is the planting pit: dig a hole roughly 30–40 cm deep and wide, fill it with a generous mix of well-rotted manure or compost and garden soil, and plant into the top of this mound. The mound also improves drainage around the crown of the plant — pumpkins dislike sitting in waterlogged soil at the base even though they need consistent moisture for the roots. If you don't have well-rotted manure, a generous application of homemade compost works well. Our composting guide covers how to make and use compost from kitchen and garden waste.

• Avoid heavy, compacted clay soil without improvement — the roots need to run widely and freely.
• A mulch of compost, straw or wood chip placed around the plant after planting helps retain moisture and suppresses weeds.
• Pumpkins prefer a slightly acidic to neutral pH, around 6.0–7.0.
• A liquid feed during the growing season (see Watering) supplements the initial soil preparation as the season progresses and nutrients are used up.

Sowing from seed after frost

Pumpkins and squash are frost-tender — a late frost will kill young plants outright. Do not plant out, or sow direct outside, until all frost risk has passed for your location. In cool temperate climates, that means starting seeds indoors or in a heated greenhouse a few weeks before the expected last frost date, then planting out once the weather has settled.

1. Sow seeds on their side. Use a 9 cm pot filled with seed compost. Place one seed per pot, on its side — this prevents the fat seed tip from rotting in moist compost. Cover lightly and place in a warm propagator or on a heated surface at around 18–20°C.
2. Germinate and grow on in bright warmth. Seeds germinate in 5–10 days. Move seedlings to a bright, warm windowsill or greenhouse bench immediately — poor light makes them stretch and weaken. Pumpkin seedlings grow fast.
3. Pot on if needed. If your last frost date is several weeks away and seedlings are outgrowing their pots, move them into a larger container rather than letting them become rootbound. A rootbound seedling under stress transplants poorly.
4. Harden off carefully. Over 7–10 days, gradually acclimatise seedlings to outdoor conditions by putting them outside for increasing periods during the day and bringing them in at night. Pumpkins are cold-sensitive even as large plants.
5. Plant into prepared soil after frost risk has passed. Plant into the top of your prepared planting mound, water in well and protect with a cloche or fleece if a cold night threatens in the first week or two after planting.

Watering at the roots

The large leaves of pumpkins and squash lose a significant amount of water through transpiration — especially on warm, sunny days — and the developing fruits themselves contain a great deal of water. Consistent, deep watering is important, particularly during fruit swelling.

• Water at the base: direct water to the root zone, not over the large leaves. Wet foliage in warm, humid conditions is a major driver of powdery mildew (see Common problems).
• Deep watering: water thoroughly and less frequently rather than little and often. Deep watering encourages roots to follow moisture downwards, making plants more drought-resilient than shallowly watered ones.
• Buried-pot watering trick: some growers sink an old flower pot or cut plastic bottle neck-down into the soil beside the plant at planting time. Pouring water into this directs it straight to the deep root zone, reducing surface evaporation and ensuring the water reaches where it's needed.
• Mulch: applying a thick mulch of compost or straw around the root zone dramatically reduces how often you need to water. See our water-wise gardening guide for more on mulching and other water-saving techniques.
• Reduce watering as harvest approaches: as fruits approach maturity and the vines start to dry back, reduce watering. Keeping the soil on the drier side at this point helps concentrate sugars in the flesh and hardens the skin — both desirable for storage.

Hand-pollination

Pumpkins and squash produce separate male and female flowers on the same plant. You can tell them apart easily: female flowers have a small, immature fruit (miniature pumpkin or squash shape) at their base, while male flowers have a plain, thin stem. The male flowers usually appear first, before the females arrive.

Outdoors, bees and other pollinators usually transfer pollen from male to female flowers during the morning when flowers are open. Under glass, or in cool, wet weather when pollinators are less active, fruit set can be poor. Hand-pollination is simple, reliable and satisfying:

• Do it in the morning, when flowers are fully open (they generally close by midday).
• Pick a fully open male flower. Peel back or fold back the petals to fully expose the pollen-covered stamen.
• Gently rub the stamen against the centre of a fully open female flower (the stigma, the sticky structure at the centre). One male flower can pollinate several females.
• A successfully pollinated female will begin to swell at the base within a few days. An unpollinated one will yellow and drop.

Limiting fruits for size and quality

Left to itself, a vigorous pumpkin plant may set many small fruits, but the energy available is finite. The plant splits that energy between however many fruits are developing. If you want large, well-formed fruits, you need to help the plant focus.

• Once two or three fruits are well established and growing steadily, pinch off any additional developing fruits or remove unpollinated flowers. This directs the plant's resources into the fruits you've kept.
• For very large pumpkins — the kind entered into shows — growers typically reduce to just one fruit per plant and may also stop the main vine growing at a certain length by pinching out the tip.
• For winter squash grown for eating, allowing two to four fruits per plant is usually the best balance between fruit size and total yield.
• Place a tile, piece of slate, or a square of wood under each developing fruit. This keeps the base of the fruit off damp soil, prevents rot at the contact point, and may help the skin harden more evenly.

Knowing when to harvest and curing for storage

Patience at harvest time pays dividends at the table. A pumpkin or squash picked too early will have thin, soft skin and underdeveloped flavour; properly ripened on the vine and then cured, it becomes a dense, flavourful store crop.

Signs of ripeness: the skin has reached the mature colour for the variety and is completely hard — it should resist your fingernail without denting or marking. The stem is beginning to dry out, turn corky and develop splits or a woody texture where it meets the fruit. The foliage of the vine is yellowing and dying back. Tapping the fruit produces a hollow sound rather than a dull thud.

Harvest before the first hard frost by cutting the stem cleanly with a sharp knife or secateurs, leaving as long a stem as possible attached to the fruit (at least 5–10 cm). A long, intact stem greatly reduces the chance of rot entering through the cut end during storage.

Curing: freshly harvested squash benefit from a curing period of one to two weeks in a warm, dry place (ideally 25–30°C) before moving to long-term storage. This hardens the skin further and helps any surface damage heal. A sunny greenhouse, conservatory or warm shed is ideal. After curing, move to a cool (around 10–15°C), dry, frost-free store with good airflow. A spare room, pantry or cool cellar all work well.

Well-cured 'Crown Prince', 'Butternut' or Hubbard-type squash can store for many months. For more on making the most of a glut and long-term food storage, see our food preservation guide.

Powdery mildew, slugs and other problems

• Powdery mildew: the most common and visible problem with cucurbits — a white, powdery coating on the upper surface of the leaves, caused by a fungal disease (several species of Erysiphe and Podosphaera). It spreads rapidly in warm, dry conditions with poor airflow. The disease weakens the plant and reduces yield but rarely kills it outright. Avoid wetting leaves, improve airflow by removing some of the lower leaves if the plant is very dense, and remove badly affected leaves promptly. Some varieties have partial resistance. A dilute solution of potassium bicarbonate in water can slow spread; baking soda solutions have also been used, but with variable results.
• Slugs and snails: a serious threat to seedlings and young plants immediately after planting. Protect newly planted cucurbits with physical barriers — copper tape, gritty mulches — or biological slug nematodes. Our natural pest control guide covers the full range of approaches. Once plants are large and established, slug damage is usually superficial.
• Blossom end rot: as with tomatoes, a dark, sunken patch on the end of the fruit indicates calcium deficiency caused by inconsistent watering. Keep the root zone evenly moist throughout fruit development.
• Vine borers (Melittia cucurbitae): a pest in North America — the larvae of a moth burrow into the base of the vine and cause it to wilt and die. Protecting the base of vines with fabric row covers until flowering helps prevent egg-laying. Inspect the base of vines regularly and remove larvae if found.
• Fruit rotting on the ground: raising developing fruits on a tile or slate prevents this. Improving drainage around the plant base is also helpful.

Pumpkin-growing checklist

• Choose varieties suited to your space — compact or bush types for smaller gardens.
• Prepare a rich, deep planting site with generous compost or well-rotted manure.
• Sow seeds indoors on their side in warmth a few weeks before your last frost date.
• Harden off seedlings carefully before planting outside.
• Plant only after all frost risk has passed — cover with fleece if uncertain.
• Water deeply at the roots, not over the leaves, to reduce mildew risk.
• Mulch around the plant base to retain moisture and suppress weeds.
• Hand-pollinate if fruit is failing to set.
• Limit fruits to two or three per plant for best quality; one per plant for show-sized specimens.
• Raise fruits off the ground on a tile or board.
• Harvest before frost when the skin is hard, the stem is corky and the vine is dying back.
• Cure in warmth for one to two weeks before moving to cool storage.