Courgette
Cucurbita pepo
The crop that most often produces more than a household can eat from two plants. Courgettes are fast, greedy and productive, and their whole management is about keeping up with them: picked small and often, a plant crops for months, while one that is allowed to mature a single marrow slows down markedly.
- Position
- Full sun
- Water
- high demand
- Drainage
- Moisture-retentive
- Grows to
- 60–90 cm × 90–120 cm
- Hardiness
- H2
- Harvest
- July to September
- Difficulty
- Straightforward
Described view
A male and a female courgette flower side by side, the female showing a small immature fruit behind the petals and the male a plain slender stalk
August
Harvest
Courgette’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 | March. | April. | ||||||||||
| Sow outdoors | May. | |||||||||||
| Plant out | May. | |||||||||||
| Harvest | July. | August. | September. |
Names that cause confusion
marrow — The same plant. A marrow is a courgette left on the plant to mature; the difference is when it was picked, not what was sown.
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.
- Sow under cover3–4 weeks before your last spring frost
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — sowing
Checked 2026-08-13
Courgettes grow very fast. Sown too early they become pot-bound and check badly at planting out.
- Sow outdoors1–4 weeks after your last spring frost
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — sowing outdoors
Checked 2026-08-13
- Plant out1–3 weeks after your last spring frost
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — planting out
Checked 2026-08-13
Conditions it needs
- Light
- Full sun
- Direct sun
- 6 hours a day or more
- Frost
- Frost tender
- Hardiness rating
- H2 (RHS)
- Grows best at
- 18–30 °C
- Germinates at
- 21–30 °C
- Soil
- Loam, Peat-free compost
- 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: Courgettes — position
Checked 2026-08-13
- Direct sunHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- FrostSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — hardiness
Checked 2026-08-13
- Hardiness ratingSourced guidancehigh confidence
- Royal Horticultural Society: RHS hardiness ratings
Checked 2026-08-13
- Grows best atHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Germinates atSourced guidancehigh confidence
- OSU Extension Service — Oregon State University: Vegetable seed germination temperatures
Checked 2026-08-13
- SoilSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — soil
Checked 2026-08-13
- Soil pHSourced guidancehigh confidence
- University of Minnesota Extension — University of Minnesota: Soil pH for vegetable crops
Checked 2026-08-13
- DrainageHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Water needsSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — watering
Checked 2026-08-13
- DroughtHorticultural consensusmoderate confidence
- Royal Horticultural Society: Courgettes — watering
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
Large soft leaves tear in wind and lose water fast on an exposed site.
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 | Courgette 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 | Courgette 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 | Courgette 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 Courgette 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 | Courgette grows perfectly well on silty without special measures, though it is not the soil it would choose. |
| Peaty and acid | Works, with one condition | Courgette 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 | Courgette 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 | Courgette 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
- 60–90 cm
- Mature spread
- 90–120 cm
- Rooting depth
- 45 cm
- Spacing
- 90 cm apart
- Row spacing
- 120 cm
Where these figures come from
- Mature heightHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Mature spreadSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — spacing
Checked 2026-08-13
- Rooting depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- SpacingSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — spacing
Checked 2026-08-13
- Row spacingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
In a container
- Minimum volume
- 30–45 litresSourced guidanceDepends on conditions
- Minimum depth
- 35 cm
Where the container figures come from
- Minimum volumeSourced guidanceDepends on conditionshigh confidence
Applies when: A courgette in a smaller pot will grow and flower but cannot hold enough water to crop through August without wilting daily.
- Royal Horticultural Society: Courgettes in containers
Checked 2026-08-13
- Minimum depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Needs a bigger pot than most people give it and will wilt flat by mid-afternoon in anything smaller. One plant per container, and feed once the first fruits set.
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 guidancehigh confidence
Checked 2026-08-13 | Rich soil with plenty of organic matter; Around a square metre per plant |
| Raised bed | Well suitedsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | One plant per square metre |
| Container | WorkableSourced guidanceDepends on conditionshigh confidenceApplies when: Needs a genuinely large container and daily watering in summer; a compact bush cultivar helps.
Checked 2026-08-13 | 30 litres or more; Daily watering in hot weather |
| Polytunnel | WorkablesourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | Space — one plant fills a lot of tunnel |
| Hydroponics | WorkablesourceGrowingHQ editorial positionmoderate confidence Genuinely productive and genuinely enormous. One plant will fill a domestic system and needs its flowers pollinating by hand indoors, and in return it crops for months.
Checked 2026-08-13 | |
| Greenhouse | MarginalsourceGrowingHQ editorial positionmoderate confidence It will grow, but a courgette crops perfectly well outdoors and occupies floor area that a crop needing the protection would use better.
Checked 2026-08-13 | |
| Windowsill | Not suitablesourceHorticultural consensusmoderate confidence Far too large, and needs insect pollination. No external citation — see the evidence type above. Checked 2026-08-13 |
Growing it
- SowingSow seeds on their edge rather than flat, about 2 cm deep, one or two per pot. Large flat-lying seeds are more prone to rotting before they germinate.2 cm
- WateringWater generously at the base, keeping water off the leaves. A courgette's roots run wider than the plant looks, and watering only at the stem misses most of them.
- MulchingMulch thickly after planting. Courgettes root shallowly and dry out between waterings without one.
- PollinationCourgettes carry separate male and female flowers and need insects to move pollen between them. Small fruits that yellow and rot at the tip are usually unpollinated rather than diseased — common in a cold wet spell or under cover, and easily fixed by hand-pollinating with a male flower.
- HarvestingCut fruit at 10–15 cm, every two or three days in warm weather. This is the single most important thing you do for a courgette: a plant left to mature a marrow slows or stops setting new fruit.
- FeedingPlant into ground with plenty of compost dug in, then feed fortnightly with a high-potassium feed once the first fruits set. A courgette that produces flowers and then small fruit that yellow and rot at the tip is usually short of water rather than food, so check that first.
- ProtectionCourgettes are annuals and are not overwintered: the first frost collapses the plant overnight and that is the end of its natural life rather than a failure. What is worth doing in autumn is clearing the plants promptly once they blacken, because the old foliage carries powdery mildew spores and slugs shelter under it. A fleece thrown over plants for an early light frost in September can buy two or three more weeks of picking, which is usually the last of the crop.
Where this guidance comes from
- SowingSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — sowing
Checked 2026-08-13
- WateringSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — watering
Checked 2026-08-13
- MulchingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- PollinationSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — poor fruit set
Checked 2026-08-13
- HarvestingSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — harvesting
Checked 2026-08-13
- FeedingSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — feeding
Checked 2026-08-13
- ProtectionSourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — cultivation
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 | Space against reward. An early plant is genuinely useful and a mature one is a metre across and will take over the house by July.Move it outside once the frosts are past |
| 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 | Space against reward, with more room to spare. |
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.
Succeeds when the conditions listed here are met and fails when they are not. The conditions are the answer, not a caveat.
source
GrowingHQ editorial positionmoderate confidence
Genuinely productive and genuinely enormous. One plant will fill a domestic system and needs its flowers pollinating by hand indoors, and in return it crops for months.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
Hand pollination is the part people are not warned about: male and female flowers open on the same plant and nothing indoors moves the pollen between them.
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.
- Deep water cultureRoots hang in aerated solution. Very productive and very unforgiving of solution temperature — warm solution holds less oxygen and root disease follows.
source
Horticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Root space
- Large — a single plant wants the volume three lettuces would use.
- Support
- Little climbing, but the plant sprawls a metre in every direction.
source
Horticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- 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
What actually goes wrong
- Warm solution. Above roughly 22 °C the water holds much less dissolved oxygen and root disease follows quickly, which is why summer is harder than winter in an indoor system.
source
Sourced guidancemoderate confidence
- Purdue Extension — Purdue University: Solution temperature and dissolved oxygen
Checked 2026-08-13
- Pump or power failure. In nutrient film and aeroponics there is no reserve at the roots, so a crop can be lost within hours; medium-based systems hold moisture and are far more forgiving.
source
Sourced guidancehigh confidence
- Purdue Extension — Purdue University: Hydroponic system design — failure modes
Checked 2026-08-13
- pH drift. The solution moves as the plants take nutrients up, and by the time deficiency symptoms appear on the leaves the cause is several weeks old.
source
Sourced guidancehigh confidence
- 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
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — timing
Checked 2026-08-13
- When it is readyPick at 10–15 cm with the flower still attached or just withering. Larger fruit is watery and the seeds coarsen.
- How to pick itCut the stalk with a knife rather than twisting, which tears the brittle main stem.
- Keeping itKeeps about a week in a refrigerator. Better picked as needed than stored.
Where the harvest guidance comes from
- When it is readySourced guidancehigh confidence
- Royal Horticultural Society: Courgettes — harvesting
Checked 2026-08-13
- How to pick itHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Keeping itHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Keep picking
What goes wrong
| Problem | How often | Notes |
|---|---|---|
| Powdery mildew | commonsourceSourced guidancehigh confidence
Checked 2026-08-13 | Near-inevitable by late summer; usually the end of the season rather than a crisis. |
| Slugs and snails | commonsourceSourced guidancehigh confidence
Checked 2026-08-13 | Newly planted courgettes are a favourite target for about a fortnight. |
| Blossom end rot | occasionalsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Damping off | occasionalsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Poor fruit set | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | Small fruits yellowing and rotting at the tip are unpollinated female flowers, not disease. |
Grown with, grown after, grown instead
Every relationship states its mechanism. A pairing nobody can explain is a pairing nobody has checked, and it does not go in.
- Closely relatedCucumberBoth cucurbits with separate male and female flowers, similar water and feeding demands, and shared susceptibility to powdery mildew, so problems and timings run in parallel.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Cucurbits
Checked 2026-08-13
Safety and edibility
- PreparationVery rarely, a courgette or marrow — usually one grown from saved seed, or from a plant that has crossed with an ornamental gourd — accumulates cucurbitacins and tastes intensely bitter. These compounds cause severe vomiting and diarrhoea.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Bitter cucurbits
Checked 2026-08-13
Taste a small piece of any courgette that smells or tastes bitter and spit it out. Discard the whole fruit and the plant it came from. Do not save seed from cucurbits grown near ornamental gourds.
- Which parts are edibleThe fruit and the flowers are both edible; male flowers can be picked freely because only the females become fruit.
source
Horticultural consensusmoderate confidence
- Royal Horticultural Society: Courgette flowers
Checked 2026-08-13
Pick male flowers — the ones on a plain thin stalk, with no small fruit behind them — and leave the females to set.
Sources for this page
GrowingHQ editorial synthesis · OSU Extension Service · Royal Horticultural Society · University of Minnesota Extension
Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-13.
If something is wrong with it
- Dark sunken patch at the bottom of a fruit — 2 causes GrowingHQ holds for courgette
- New growth twisted, puckered or distorted — 2 causes GrowingHQ holds for courgette
- Flowers dropping without setting fruit — 2 causes GrowingHQ holds for courgette
- White powdery coating on leaves — 2 causes GrowingHQ holds for courgette
- Plant wilting although the soil is moist — 3 causes GrowingHQ holds for courgette
Something else? Work through it with the diagnostic tool.