How to Grow Zucchini in the USA
On this page
- Zucchini (Cucurbita pepo)
- Quick Facts
- At a Glance
- Regional Planting Calendar
- Do You Need Two Plants? (And Does Tomato Feed Help?)
- Growth Stages
- Soil & Growing Conditions
- Harvest & Storage
- Diseases
- Pests
- Pollination
- Plan your Zucchini planting
- Growing Zucchini in another region
- Sources
- Nutrient Issues
- Can You Grow Zucchini From Kitchen Scraps?
- Frequently Asked Questions
In the USA, zucchini go in the ground early February to late May depending on your region — there are 7 separate regional sowing windows, from early February in the Deep South & Gulf Coast to late May in the Intermountain West. Fruit is ready 50–55 days after sowing.
The short answer
- Plant
- Early March to late March
- Ready in
- 55 days after planting out
- Site
- 6+ hours of sun, soil pH 6–6.5
- Biggest risk
- Grey mould
Core growing advice on this page is checked against named horticultural sources — see References.
Zucchini (Cucurbita pepo)
Also known as: Zucchini · 18 sources cited · Verified
Quick Facts
At a Glance
Regional Planting Calendar
| Region | Sow |
|---|---|
| Pacific Northwest derived | early March to late March |
| Northeast & New England derived | early April to late April |
| Lower Midwest & Ohio Valley derived | mid April to early May |
| Intermountain West derived | early May to late May |
| N. Plains & Upper Midwest derived | late April to mid May |
| Mid-Atlantic & Upper South derived | early April to late April |
| Deep South & Gulf Coast derived | early February to late February |
Rows marked derived are interpolated between regions our sources do state, because no source we consulted gives a figure for that region specifically. They are deliberately wider to reflect that uncertainty.
Pacific Northwest - detail & sources
DERIVED from this region's own frost normal, not quoted for the region. Plant when soils are 65°F or after all frost danger has passed. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Applied to a mean last frost of 8 March (NOAA NCEI 1991-2020 for the USA; Environment and Climate Change Canada normals for Canada), that gives 8 March to 29 March. Your own local frost date is what matters — a region spans a range, and this figure comes from one representative station within it.
Northeast & New England - detail & sources
DERIVED from this region's own frost normal, not quoted for the region. Plant when soils are 65°F or after all frost danger has passed. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Applied to a mean last frost of 6 April (NOAA NCEI 1991-2020 for the USA; Environment and Climate Change Canada normals for Canada), that gives 6 April to 27 April. Your own local frost date is what matters — a region spans a range, and this figure comes from one representative station within it.
Lower Midwest & Ohio Valley - detail & sources
DERIVED from this region's own frost normal, not quoted for the region. Plant when soils are 65°F or after all frost danger has passed. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Applied to a mean last frost of 16 April (NOAA NCEI 1991-2020 for the USA; Environment and Climate Change Canada normals for Canada), that gives 16 April to 7 May. Your own local frost date is what matters — a region spans a range, and this figure comes from one representative station within it.
Intermountain West - detail & sources
DERIVED from this region's own frost normal, not quoted for the region. Plant when soils are 65°F or after all frost danger has passed. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Applied to a mean last frost of 6 May (NOAA NCEI 1991-2020 for the USA; Environment and Climate Change Canada normals for Canada), that gives 6 May to 27 May. Your own local frost date is what matters — a region spans a range, and this figure comes from one representative station within it.
N. Plains & Upper Midwest - detail & sources
DERIVED from this region's own frost normal, not quoted for the region. Plant when soils are 65°F or after all frost danger has passed. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Applied to a mean last frost of 25 April (NOAA NCEI 1991-2020 for the USA; Environment and Climate Change Canada normals for Canada), that gives 25 April to 16 May. Your own local frost date is what matters — a region spans a range, and this figure comes from one representative station within it.
Mid-Atlantic & Upper South - detail & sources
DERIVED from this region's own frost normal, not quoted for the region. Plant when soils are 65°F or after all frost danger has passed. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Applied to a mean last frost of 4 April (NOAA NCEI 1991-2020 for the USA; Environment and Climate Change Canada normals for Canada), that gives 4 April to 25 April. Your own local frost date is what matters — a region spans a range, and this figure comes from one representative station within it.
Deep South & Gulf Coast - detail & sources
DERIVED from this region's own frost normal, not quoted for the region. Plant when soils are 65°F or after all frost danger has passed. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Applied to a mean last frost of 2 February (NOAA NCEI 1991-2020 for the USA; Environment and Climate Change Canada normals for Canada), that gives 2 February to 23 February. Your own local frost date is what matters — a region spans a range, and this figure comes from one representative station within it.
Do You Need Two Plants? (And Does Tomato Feed Help?)
Do you need two plants to get fruit? No -- one is enough. Courgettes are monoecious, carrying separate male and female flowers on the same plant (Iowa State University Extension confirms this directly: "they produce separate male and female flowers on the same plant"). What you do need is pollinating insects to move pollen between those flowers, since the plant can't do it alone -- in cool, dull early-summer weather when bees are less active, fruit can fail to set or rot off while small. If that happens, hand-pollinate: transfer pollen from a freshly opened male flower onto a female flower with a soft brush, or press the two together.
Does tomato feed help? Yes, genuinely -- tomato feed is a high-potash liquid fertiliser, and that's the exact feed type called for once the first fruits start to swell (every 10-14 days for container-grown plants; in-ground plants in reasonable soil usually don't need it at all).
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Sowing & Germination | 0 | SOWING DEPTH: 13mm (½in) deep when started indoors in small pots; 2.5cm (1in) deep when sown direct outdoors, two or three seeds per station at least 90cm (3ft) apart, thinned to the strongest seedling (RHS). TIMING: sow indoors in April or early May for an earlier, more reliable crop; sow direct outdoors from late May or early June once the soil has warmed and frost risk has passed (RHS). GERMINATION: needs 18-21°C (65-70°F); frost-tender at every stage and must never be sown or planted out while frost is still likely. |
| Vegetative Growth & Planting Out | 3 | SPACING: harden off indoor-raised plants and plant out, or thin direct-sown seedlings, to at least 90cm (3ft) apart -- allow roughly one square metre per plant (RHS). Water at the base rather than over the leaves to reduce the risk of grey mould and powdery mildew, and keep the soil consistently moist (RHS; Clemson: moisten soil to a depth of 6in with a uniform moisture supply). |
| Flowering & Pollination | 6 | Plants are monoecious, carrying separate male and female flowers on the same vine. Male flowers appear first and lack a swelling behind the petal; female flowers have a miniature fruit already visible at the base (UMD). Bees normally carry pollen from male to female flowers; in cool, dull early-summer weather insect activity drops and fruit can fail to set or rot off while small -- this resolves as the weather warms, or can be corrected by hand-pollinating: transfer pollen from a freshly opened male flower onto the stigma of a female flower with a soft brush, or press the two flowers together (RHS; UMD). Feed container-grown plants every 10-14 days with a high-potash liquid fertiliser once the first fruits start to swell; in-ground plants in reasonable soil usually need no feeding (RHS). |
| Fruit Development | 7 | Fruit swells rapidly once set. Keep watering consistent -- irregular watering and poor pollination are the main causes of fruit rotting or failing to develop. Watch the foliage for the powdery, dusty white coating of powdery mildew and fuzzy grey growth of grey mould, both encouraged by still, humid air and overhead watering (RHS); good airflow and watering at the base help prevent both. |
| Ripening & Harvest | 8 | HARVEST: cut courgettes while small, tender and full of flavour, at 10-12.5cm (4-5in) long, using a knife rather than pulling to avoid damaging the plant (RHS). Check plants daily once cropping begins and pick every couple of days -- a single healthy plant can produce three or four fruits a week in good weather; regular picking keeps more fruit coming, while a fruit left on the plant swells into a marrow and slows further production (RHS; Clemson). No storage method is given by RHS; Clemson recommends refrigerating in a plastic bag for up to a week. |
Soil & Growing Conditions
Harvest & Storage
Diseases
Pests
Pollination
Honeybees Apis mellifera
RHS: "Pollination is usually carried out by insects", with honeybees named as the main pollinators. Poor fruit set follows "Lack of pollination due to low activity of pollinating insects, mainly honeybees, during periods of poor and cold weather"; symptoms are that "Young fruitlets are aborted and will drop off" and "The flower end of the fruit will often shrivel up and start rotting". Growing under cover limits insect access. Hand-pollinate by picking a male flower (no fruitlet at its base), removing the petals to expose the anthers, and pressing it into the centre of the female flowers -- "One male flower will pollinate several female flowers".
Plan your Zucchini planting
When to sow and plant Zucchini depends on your own frost dates. Check the USA vegetable planting calendar, or the month-by-month guides that cover Zucchini: July, August. To work out where it fits in your beds, sketch your plot in the free Garden Layout Planner.
Growing Zucchini in another region
Sowing dates, frost timing and local advice differ by country. Use the guide for where you garden.
Sources
-
Bacterial wilt (no chemical control once infected; control cucumber beetles at first sign); powdery mildew at 50-90°F in dry weather with high humidity; downy mildew in moist conditions; gummy stem blight surviving on debris year to year, no resistant varieties, rotate to non-hosts such as corn for two or more years; anthracnose needing rainy cool weather for several days, overwintering on old vines, rotate three years; Alternaria leaf spot with bull's-eye rings at 60-90°F; Cercospora leaf spot at 79-90°F reinfecting new leaves every 7-10 days, rotate away from cucurbits 2-3 years; Fusarium wilt surviving in soil for many years with no chemical treatment.
-
Plant when soils are 65°F or after all frost danger has passed, sowing 4-6 seeds 1-2 in deep in mounds 4 ft apart and thinning to two plants; transplants 2 ft apart in rows 4-6 ft apart. With mulch and row covers, seeds or plants can be set out 2-3 weeks before the last frost. Do not apply organic mulch until soils reach 75°F. Summer squash takes 35-45 days to flowering; winter squash 45-55 days to mature from flowering. The first flowers are almost always male; female flowers carry a small fruit behind the flower. Harvest summer squash immature, 3-5 days after the flower opens, and winter squash once the rind resists a fingernail. Summer squash stores 2-4 days at 45-55°F; winter squash in cool dry conditions at 50-55°F.
These 7 sources are specific to this region. The full list of 18 sources behind this guide (Clemson Cooperative Extension, FAO EcoCrop, Global Biodiversity Information Facility (GBIF) and others) is in the references of our UK guide to courgettes; they describe the plant itself, which is the same wherever it grows.
Nutrient Issues
Can You Grow Zucchini From Kitchen Scraps?
No, not from the harvested fruit itself. Regrowth from scraps works for crops like spring onion or lettuce because the piece you keep still carries a live growing point — a zucchini fruit doesn't have one. N.C. Cooperative Extension notes that fruit picked for eating is "harvested before they're fully mature," which "also means the seeds inside are not likely to result in a viable plant" — and the cut end of the fruit has nothing left to regrow from either way.
Gardening forums sometimes describe rooting a stem cut from a still-growing plant, not a harvested fruit — but that isn't backed by any horticultural authority we could find, and it isn't how zucchini is normally propagated. For a repeat harvest, sow seed: either bought seed, or seed saved from a fruit deliberately left on the plant until it's oversized and the skin has hardened and turned yellow — not one picked for the table.
Frequently Asked Questions
When should I sow courgettes in the USA?
In Deep South & Gulf Coast, from early February. In Intermountain West, wait until early May. Treat these as a guide rather than a fixed date — the governing rule is to sow only once frost risk has passed and temperatures are reliably warm enough.
When do I sow courgettes?
Sow early February to late May, at around 64°F (18°C) for germination.
How long do courgettes take to grow?
Typically 55 days after planting out, depending on cultivar and growing conditions.
What soil pH do courgettes need?
A pH of about 6–6.5. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect courgettes?
Our data links 9 diseases and 10 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
Almost everything on this page resolves to your own frost dates rather than the calendar — the last spring frost moves by roughly two months between zone 3 and zone 10. The USA Garden Planner works from your zone so the timing is already decided before the season starts.
Get the USA Garden Planner →Instant PDF download · Written for US growing conditions
How this guide is put together
The growing data on this page — sowing windows, pests, diseases, soil and site requirements — comes from named horticultural sources, listed in References below, checked against USDA hardiness-zone and frost-date data, with Cooperative Extension sources cited directly where one exists for a crop. An automated pipeline assembles that verified data into the page you're reading: it selects which facts to lead with and builds the surrounding prose and layout. It does not invent a date, a source or a number — where a verified value for a field isn't available, the page leaves it out rather than guessing. A person reviews and publishes each page; nothing goes live unverified.
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Last verified 2026-08-06
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