Cucurbita pepo, C. maxima or C. moschata (species varies by variety)

Summer squash is eaten fresh while small; winter squash is grown to full maturity and stored. In a short Scottish season it is the winter types' need for a long, uninterrupted ripening period that is the risk to plan around.

Squash, pumpkins and courgettes are all closely related cucurbits. Squash splits into two crops that share one name, and which one you choose changes almost everything else about how you grow it.

Choosing a type

Summer squash has thin skin, is picked young and tender, isn't suited to long storage, and is eaten fresh through summer. Winter squash is left to grow to full maturity, develops a hard skin, and can be stored for months once properly cured. Both come in bush or trailing forms, which matters for spacing more than for the summer/winter choice itself.

Preparing the ground

Choose a sunny spot with rich, moisture-retentive soil that doesn't waterlog. Cucurbits such as squash do best at a soil pH of 6.5 to 7.5 (Utah State University Extension), so test your soil first. Prepare individual planting holes about 30cm wide and deep, filled with soil mixed with garden compost or other organic matter, or mulchA layer of material spread over the soil around plants to suppress weeds, retain moisture, and improve soil structure as it breaks down. Full definition → the surface for a no-digA growing method that avoids turning the soil over, building fertility instead by adding organic matter on the surface. Full definition → bed. In containers, use a pot at least 45cm wide with peat-freeCompost made without peat, which is harvested from a slow-forming, carbon-storing wetland habitat that peat extraction damages. Full definition → multi-purpose or soil-based compost, and leave plenty of space around it for air circulation, which helps prevent fungal disease.

Sowing

Sow indoors mid-to-late April, one seed on its side, 13mm deep, in a 7.5cm pot at 18-21°C in a heated propagator, covered until germinationA seed sprouting: breaking dormancy and putting out its first root and shoot, given the right warmth and moisture. Full definition →. Outdoors, sow late May or early June, 2.5cm deep, two or three seeds per site protected with a clocheA small, portable clear cover placed over an individual plant or short row to trap warmth and keep off wind, rain and pests. Full definition → or fleeceA lightweight, breathable fabric laid or draped over plants to trap a little warmth and keep off frost, wind and some flying pests. Full definition →, thinned to the strongest seedling.

Planting CalendarTime squash around your last frostSown indoors mid-to-late April, planted out only once hardened offGradually getting young plants raised indoors used to outdoor conditions over 7–14 days before planting out, so cold, wind and direct sun don't shock or damage them. Full definition → and frost has passed.
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Planting out

Plant out after the last frost, once hardened off. Space bush varieties 90cm apart and trailing varieties 1.5m apart, since spacing depends on habit; Garden Organic's range is a tighter 60-90cm without distinguishing habit. Protect young plants from slugs and snails, especially in damp weather.

In containers, keep one plant per pot and leave space between pots: good air circulation around the plant matters as much as soil prep, since still, humid air around crowded leaves encourages fungal problems later in the season.

Varieties

The three varieties below carry the RHS Award of Garden Merit, a UK-wide award rather than a Scottish one.

Harlequin, a compact winter squash, and Harrier, a butternut type bred for short growing seasons (about 100 days to maturity), are two more winter types with an AGMThe RHS's Award of Garden Merit: a UK-wide trials award for reliable performance, not a Scotland-specific recommendation. Full definition →. Sunbeam (AGM) is a similar small yellow patty-pan but tenderer (H1cThe RHS's H1a–H7 scale for how much cold a plant can survive outdoors, H1a being tender indoor-only and H7 hardy anywhere in the UK. Full definition →), so keep it under cover until nights are reliably mild.

★ Our pick for Scotland

Sweet DumplingAGM

Winter squash, small fruit, cream with green stripes, orange flesh

The lowest-risk winter squash to finish ripening in a short season.

Why this one: The smallest-fruited winter squash with an AGM. Winter squash needs maximum ripening time on the plant before harvest, and a smaller fruit is the more realistic bet against an autumn that can turn before a larger squash finishes colouring and hardening.

Also worth considering

SunburstAGM

Summer squash, patty-pan, small fruit, yellow skin

A summer squash sidesteps the winter-squash ripening risk entirely: picked young and tender, it never needs to reach full maturity at all, the lowest-risk route to a real harvest in an uncertain season.

Crown PrinceAGM

Winter squash, trailing, bluish skin, orange flesh

A trailing winter squash with bluish skin and orange flesh, for growers with the space, shelter and season margin to attempt a larger keeper. It carries more ripening risk than Sweet Dumpling.

Best Squash Varieties for Scotland → compares all named squash varieties head-to-head, with the practical detail that doesn't fit in a summary card.

Care

Water regularly, especially once fruiting starts, and water directly to the soil rather than over the leaves: insufficient moisture, not excess, is what encourages powdery mildew on this crop. Mulch thickly after planting to retain moisture and suppress weeds, leaving a gap around the stem base to prevent rot. Ground-grown plants rarely need feeding; container plants do best with an organic-based, high-potassium liquid fertiliser every 10-14 days once the first fruits start to swell. As winter squash fruit develop, set them on a tile or board to keep them off damp soil, where they are more likely to rot.

A winter squash fruit resting on a tile to keep it off damp soil and prevent rot
Squash set on a tile as it develops, off damp soil.

Trailing types can sprawl freely, be trained in circles with short canes, or trained vertically up an arch, pergola, trellis or wigwam, with netting to support the fruit; cut back stems that stray too far. Pinch outRemoving the soft growing tip of a stem to stop upward growth and make the plant branch out sideways instead. Full definition → the growing tips of trailing stems once they reach about 60cm.

Winter squash needs to reach full maturity on the plant before harvest, with its skin fully hardened and coloured, if it is to store well. A smaller-fruited variety, or a summer type altogether, is the safer bet than gambling on a big keeper squash finishing in time.

Harvesting

Summer squash is ready from mid-summer: pick small and tender, regularly, which keeps the plant producing more. Winter squash is judged ready by colour and sound, not size: fully coloured, and sounding hollow when tapped, harvested before the first frost. Cut with at least 10cm of stem still attached; cutting closer leaves a soft spot on the fruit that's prone to rotting in storage.

Secateurs cutting a winter squash from the vine leaving at least 10cm of stem attached
Squash cut with at least 10cm of stem attached, since a closer cut leaves a soft spot prone to rot.

To store winter squash, let it harden in the sun for one to two weeks, outdoors or under cover, then keep it in a well-ventilated place at 10-15°C, with fruits spaced so they don't touch. Most varieties keep for three months or more; check regularly for deterioration.

How to Store Squash & Pumpkins for Winter → goes deeper on why curing has to happen before storage, and how long each type keeps.

Common problems

See more problems
  • Frost damage affects this tender crop at both ends of the season, at planting and at harvest.
Garden MythsWhat's true about growing squash?Every common claim checked: what holds up, what the sources argue over, and what has been tested and found false.
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Common questions

Is squash the same as pumpkin?

Botanically, yes: pumpkins are closely related cucurbits and treated as a type of winter squash, though the practical concerns differ: giant-fruit technique for pumpkins, a summer/winter split for squash. See also: Squash Myths →

Why did my winter squash rot in storage?

Often the stem was cut too close (leave at least 10cm, or the cut leaves a soft rot-prone spot) or the fruit was picked by size rather than by colour and the hollow-sound tap test, which signals a hardened, storable skin. Curing in the sun for one to two weeks before storing also matters. See also: Squash Myths →

Does powdery mildew on squash mean I've been overwatering?

No, the reverse: insufficient moisture is what encourages powdery mildew on squash, so water regularly and directly to the soil rather than cutting back. See also: Squash Myths →

Is squash spacing the same for every variety?

No: bush varieties need about 90cm, trailing varieties around 1.5m, so check which habit your variety has before spacing it. See also: Squash Myths →

More on squash

Sources

Show the 3 sources
  • extension.usu.edu: Soil pH 6.5 to 7.5 ideal for cucurbits
  • RHS: the summer-vs-winter distinction, soil prep, sowing method and temperature for indoor/outdoor routes, spacing by habit (bush/trailing), watering and the powdery-mildew link to underwatering, mulching, feeding, training on supports, winter-squash ripening and the tile/board technique, harvesting method for both types, curing and storage conditions, six named AGM varieties, slugs, grey mould, powdery mildew, frost damage
  • Garden Organic: sowing method, pinching out trailing stems at 60cm, tile-under-fruit technique, the hollow-sound ripeness test, and the cut-with-stalk/cure-before-storing method; gives a different germination temperature (13C) against the RHS 18-21C, and a tighter transplant spacing (60-90cm) not split by growth habitA plant's characteristic shape and manner of growth, such as upright, spreading, creeping or bushy. Full definition →