Winter squash
Cucurbita maxima
The squash worth eating, and a separate record from pumpkin because the advice diverges at every point: these are grown for flavour and for storage, cured properly they keep until spring, and butternut in particular needs a warmer summer than much of Britain reliably provides.
- Position
- Full sun
- Water
- high demand
- Drainage
- Moisture-retentive
- Grows to
- 40–60 cm × 150–250 cm
- Hardiness
- H2
- Harvest
- September and October
- Difficulty
- Some care needed
August
Nothing to do
No sowing, planting, harvesting or pruning window falls in August.
Coming next month: harvest.
Winter squash’s year
Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.
| Activity | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow under cover | April. | May. | ||||||||||
| Plant out | May. | |||||||||||
| Harvest | September. | October. |
Timing that travels
The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.
- Plant out1–3 weeks after your last spring frost
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Winter squash — plant out
Checked 2026-08-13
Conditions it needs
- Light
- Full sun
- Frost
- Frost tender
- Hardiness rating
- H2 (RHS)
- Grows best at
- 18–30 °C
- Germinates at
- 15–35 °C
- Soil
- Loam
- Soil pH
- 6–7
- Drainage
- Moisture-retentive
- Water needs
- high
- Drought
- poor tolerance
- Waterlogging
- poor tolerance
- Heat
- good tolerance
- Wind and exposure
- poor tolerance
Where these figures come from
- LightSourced guidancehigh confidence
- Royal Horticultural Society: Winter squash — position
Checked 2026-08-13
- FrostSourced guidancehigh confidence
- Royal Horticultural Society: Winter squash — hardiness
Checked 2026-08-13
- Hardiness ratingSourced guidancemoderate confidence
- Royal Horticultural Society: RHS hardiness ratings
Checked 2026-08-13
- Grows best atSourced guidancemoderate confidence
- Royal Horticultural Society: Winter squash — temperature
Checked 2026-08-13
- Germinates atSourced guidancemoderate confidence
- Royal Horticultural Society: Seed germination temperatures
Checked 2026-08-13
- SoilSourced guidancemoderate confidence
- Royal Horticultural Society: Winter squash — soil
Checked 2026-08-13
- Soil pHSourced guidancemoderate confidence
- Plant Finder — Missouri Botanical Garden: Cucurbita maxima — culture
Checked 2026-08-13
- DrainageSourced guidancemoderate confidence
- Royal Horticultural Society: Winter squash — soil
Checked 2026-08-13
- Water needsHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- DroughtHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- WaterloggingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- HeatHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Wind and exposureHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
On your soil
Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.
| Soil | Verdict | Why |
|---|---|---|
| Heavy clay | Works, with one condition | Winter squash will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
| Sandy | Works, with one condition | Winter squash will crop on sandy, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure. |
| Chalky and alkaline | Struggles here | Winter squash struggles on chalky and alkaline: The soil is substantially too alkaline for it: it wants pH 6 to 7, and this soil sits around 7.8 to 8.5. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering. A container or a raised bed of imported soil sidesteps the problem entirely. |
| Loam | Prefers this soil | Loam suits Winter squash as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering. |
| Silty | Grows well here | Winter squash grows perfectly well on silty without special measures, though it is not the soil it would choose. |
| Peaty and acid | Works, with one condition | Winter squash will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
| Shallow over rock | Works, with one condition | Winter squash will crop on shallow over rock, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure. |
| Made ground and urban soil | Works, with one condition | Winter squash will crop on made ground and urban soil, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
Not sure which you have? Four hand tests will settle it.
Space and spacing
- Mature height
- 40–60 cm
- Mature spread
- 150–250 cm
- Rooting depth
- 45 cm
- Spacing
- 120–180 cm apart
Where these figures come from
- Mature heightHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Mature spreadHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Rooting depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- SpacingSourced guidancemoderate confidence
- Royal Horticultural Society: Winter squash — spacing
Checked 2026-08-13
In a container
- Minimum volume
- 40 litres or more
Where the container figures come from
- Minimum volumeHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Only the compact bush forms, and even then the yield is a fraction of a plant in the ground.
Where and how you can grow it
Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.
| Method | Suitability | What it needs |
|---|---|---|
| Open ground | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Traditional dug bed | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Raised bed | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Greenhouse | WorkablesourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Polytunnel | WorkablesourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Container | MarginalsourceSourced guidancemoderate confidence
Checked 2026-08-13 | 40 litres; Bush forms only |
| Hydroponics | MarginalsourceGrowingHQ editorial positionmoderate confidence The pumpkin's objection with a longer season on the end: a winter squash must also ripen and harden its skin, which takes weeks after the fruit is full size.
Checked 2026-08-13 |
Growing it
- HarvestingLeave the fruit on the plant as long as the weather allows and cut with a long stalk. An unripe squash does not store, and the stalk is where rot enters if it is cut short.
- ProtectionCure the cut fruit somewhere warm and airy for about ten days before storing. This step is what turns a four-week squash into a five-month one, and it is the one most often skipped.
Where this guidance comes from
- HarvestingSourced guidancehigh confidence
- Royal Horticultural Society: Winter squash — care
Checked 2026-08-13
- ProtectionSourced guidancehigh confidence
- Royal Horticultural Society: Winter squash — care
Checked 2026-08-13
Is it worth putting under cover?
Whether it will grow there is on the methods table above. This is whether the space is well spent, which is a different question and usually the one being asked.
| Structure | What protection is worth | What decides it |
|---|---|---|
| Greenhouse | Extends the seasonsourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Ripening. A squash needs to finish and harden its skin before the cold, and in a poor northern summer cover is what allows it — but only if there is room for the vine. |
| Polytunnel | Extends the seasonsourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Ripening, with room for the vine to run. |
Growing it without soil
Nearly anything can be grown in a soilless system by somebody with enough equipment. The useful question is whether it is worth it, in which technique, and what goes wrong.
It can be made to grow, but a soilless system is the wrong tool — usually because of rooting volume, running cost, or a result no better than a pot of compost.
source
GrowingHQ editorial positionmoderate confidence
The pumpkin's objection with a longer season on the end: a winter squash must also ripen and harden its skin, which takes weeks after the fruit is full size.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
Curing the skin is what makes it store until spring, and it happens after the growing is finished.
Techniques that suit it
- Drip-fed mediumSolution is dripped into an inert medium around each plant. The most forgiving technique and the one that suits large, long-season, heavy crops.
Horticultural consensusDepends on conditionsmoderate confidence
Applies when: Only in a very large system.
No external citation — see the evidence type above.
Checked 2026-08-13
- Root space
- Very large.
- pH band
- 5.5–6.5
Where these figures come from
- Root spaceHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- pH bandSourced guidancehigh confidence
Outside roughly this band, individual nutrients become unavailable even when they are present in the solution — which is why a crop can starve in a full reservoir.
- Purdue Extension — Purdue University: Hydroponic solution management — pH
Checked 2026-08-13
No nutrient recipes here
GrowingHQ records pH bands, which are measurable properties of nutrient availability, and deliberately records no EC or PPM targets and no mixing instructions. Published targets vary by cultivar, growth stage, water source and technique, and the figures that apply to your system are on the product you bought.
Harvesting
- When it is readySkin hard enough that a thumbnail leaves no mark, stalk corky. Cure in warmth for ten days after cutting — an uncured squash rots in storage within weeks and a cured one lasts until spring.
- How to pick itCut with secateurs leaving a good length of stalk, handling the fruit from underneath rather than by the stem. Get them in before the first frost, then cure them somewhere warm and dry for a week or two: uncured squash keeps for weeks, properly cured squash keeps until spring, and the only difference is the curing.
- Keeping itCured and stored at around 10–15 °C, most types keep four to six months. This is the whole point of a winter squash and it depends entirely on the curing step.
Where the harvest guidance comes from
- When it is readySourced guidancehigh confidence
- Royal Horticultural Society: Squash — harvesting and curing
Checked 2026-08-13
- How to pick itSourced guidancehigh confidence
- Royal Horticultural Society: Winter squash — harvesting
Checked 2026-08-13
- Keeping itSourced guidancehigh confidence
- Royal Horticultural Society: Squash — storage
Checked 2026-08-13
What goes wrong
| Problem | How often | Notes |
|---|---|---|
| Powdery mildew | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Slugs and snails | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 |
Sources for this page
GrowingHQ editorial synthesis · Plant Finder · Royal Horticultural Society
Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-14.