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Growing pumpkins

Cucurbita maxima, C. moschata and C. pepo. A sprawling summer vine grown for its hard-skinned fruit, which ripens on the vine, is cured in the sun and keeps for months. It wants sun, warmth, plenty of room and steady water, most kinds need three to four frost-free months, and frost kills it. These steps work anywhere: they go by soil and weather, not by month. Also called winter squash (US, Canada and the UK, where pumpkin usually means the round orange kinds).

How a pumpkin grows

1. 
   SowFlat seeds, sown on their sideUp in 1–2 weeks
2. 
   ThinKeep the strongest one or twoAbout 2 weeks
3. 
   Vines runBig leaves; mulch goes down4–6 weeks
4. 
   FlowerMale flowers open firstAbout 6–8 weeks
5. 
   PollinateFemales have a baby pumpkin behindA week or two later
6. 
   SwellFruits grow; pinch the vine ends1–3 weeks after flowering
7. 
   RipenLifted off the soil, it colours and hardens6–8 weeks after flowering
8. 
   CureCut with a stalk, then 7–10 days in sunWhen the vine dies back

Times run from sowing in the bed and vary with the variety and the weather: small kinds are quickest, big ones take the longest. Seedlings raised in pots go out at 3–4 weeks old.

Growing it, step by step

1. Is it right for you?

   • Pumpkins need a long, warm, frost-free season: about three to four months for most kinds, with days averaging around 18–27°C (65–80°F). Small kinds are quicker.
   • Frost kills the vines, and frosted fruit won't store. In cool summers they grow slowly and crop poorly, and above about 35°C (95°F) growth slows too.
   • They take room. Trailing kinds need about 1.5 m (5 ft) each way and their vines run further still; train them in a circle, or grow small-fruited kinds up a strong support. Bush kinds need about 90 cm (3 ft) and grow in a pot at least 45 cm (18 in) wide.

2. When to plant

   Sow where they are to grow once the soil is at least 15°C (60°F) and the last frost has passed, early enough for the fruit to ripen before the first frost of autumn. For an earlier start, sow in small pots indoors three to four weeks before you plan to plant out, kept warm at 18–21°C (65–70°F), and plant out after the last frost.

   Short, cool summers: start seeds in pots indoors, plant out after the last frost under fleece, and choose quick, small-fruited kinds. Mild climates: sow in late spring, once the soil is warm, for a crop in autumn. Hot or subtropical places: sow from late winter, as soon as the soil is warm. Give them sun and air: mildew is worst in humid weather. Tropics: the cooler, drier months, on mounds so the roots drain.

3. Prepare the bed

   • A warm, sunny spot, sheltered from strong wind. A few weeks before sowing, dig plenty of compost or well-rotted manure into each planting spot, about 30 cm (1 ft) wide and deep.
   • Where drainage is poor, plant on a low mound: young plants rot in wet soil.
   • Slightly acid soil suits them best, pH 6.0–6.5, but most garden soils grow them well. See soil pH.
   • Avoid beds that grew pumpkins, zucchini, cucumbers or melons in the last two to three years. They share the same pests and diseases.

4. Sow and plant

   • Sow two or three seeds 2–3 cm (about 1 in) deep in each spot where a plant is to grow. Lay the flat seeds on their side.
   • Or sow one seed on its side 1–1.5 cm (½ in) deep in a small pot, about 7.5 cm (3 in) across, and keep it warm.
   • A week or so before planting out, harden seedlings off: put them outside by day and bring them in at night. Plant them at 3–4 weeks old, at the same depth as in the pot, without disturbing the roots.
   • Space trailing kinds 1.5 m (5 ft) apart, in rows 2 m (6½ ft) apart. Bush kinds need only 90 cm (3 ft).

5. Get it started

   • Water well after sowing, then keep the soil just moist until the seedlings are up. Seeds rot in cold, soggy soil.
   • Water seedlings you plant out every day for the first week, until they settle.
   • About two weeks after sowing, keep the strongest one or two seedlings in each spot and snip the others off at soil level.
   • Protect young plants from slugs and snails, and cover them with fleece if a cold night is forecast.

6. Keep it growing

   • Water: a deep soak at the roots about twice a week, best in the morning, more in hot, dry weather. Watering the soil, not the leaves, helps against powdery mildew. They need it most while flowering and setting fruit. Once the fruit is full-sized and colouring, ease off to about once a week. A 15 cm (6 in) pot sunk beside the stem takes water straight to the roots, and a cane beside it marks the spot once the vines spread.
   • Mulch: once the soil is warm, about two weeks after planting, spread straw about 7 cm (3 in) deep to hold moisture, keep weeds down and keep the fruit off bare soil. Keep it off the stem.
   • Feed: good soil needs little or nothing. On poor soil, or for big pumpkins, give two high-potash liquid feeds two weeks apart once the fruits start to swell, and none once they are colouring. In pots, feed every 10–14 days from then. Too much nitrogen grows vine instead of fruit.
   • Fruit set: the first flowers are mostly male and fall off, which is normal. Female flowers have a tiny round fruit behind them. If those baby fruits yellow and rot (poor fruit set), hand-pollinate in the morning: pull the petals off a male flower and dab its pollen into an open female flower.
   • Vines: no regular pruning. Guide the runners where you want them, or cut back any that stray. Once three or four fruits have set, pinch out the tip of each vine so the plant ripens those. For big pumpkins, keep only the best two or three fruits.
   • Lift the fruit: once the fruits are a good size, sit each one on a tile, board or thick straw so the underside doesn't rot on damp soil. Let the sun reach them: trim off a leaf or two if they are shaded.
   Spit out bitter fruit. A pumpkin that tastes bitter can make you ill, and cooking doesn't make it safe. Throw it away. Don't sow seed saved from your own plants: crossed with ornamental gourds, it can grow bitter fruit.

7. Watch for problems

   The common ones, with a Garden help page each where there is one:

   Powdery mildewDowny mildewAnthracnoseBacterial wiltMosaic virusGrey mouldPoor fruit setSlugs and snailsAphidsCucumber beetlesSquash bugsSquash vine borerRoot-knot nematodes

8. Harvest

   • Leave them on the vine to ripen fully. They're ready when the skin is fully coloured and too hard to mark with a fingernail, the fruit sounds hollow when tapped, and the tendril nearest it has dried brown. Often the vine is dying back by then.
   • Pick on a dry day. Cut the stalk with secateurs or a sharp knife, leaving 5–10 cm (2–4 in) on the fruit. Never carry a pumpkin by its stalk: if it tears away, the fruit rots from the wound.
   • Bring them all in before the first frost: frosted pumpkins don't store. Eat any bruised or damaged ones first.

9. After harvest

   • Cure them first: leave them in full sun for 7–10 days, on a rack or straw so air gets underneath, until the skin is hard. A greenhouse works too. Cover them if frost is forecast.
   • Store them somewhere cool, dry and airy, around 10–15°C (50–60°F), not touching each other. Check them now and then and use any soft ones first. Depending on the kind, they keep for two to six months: big, hard-skinned kinds keep longest.
   • Pull the vines out once you've picked. Bin plants with mosaic virus rather than composting them.
   • Next in that bed: a cool-season crop such as peas, broad beans, garlic or leafy greens. Keep pumpkins, zucchini, cucumbers and melons out for two to three years.

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Sources

• RHS: How to grow pumpkins
• Gardening Australia: Pumpkin power
• Clemson Cooperative Extension: Pumpkins and winter squash
• Utah State University Extension: How to grow pumpkins in your garden
• Tox Info Suisse: Bitter pumpkins and courgettes

Facts checked Friday 23 October 2026. General guidance only: local advice comes first.