zucchini

When to sow zucchini?

Botanical name
Cucurbita pepo
Family
Cucurbitaceae

Zucchini is sown outdoors from May to June, 2 cm deep. It germinates in 10 to 12 days. It is harvested from July to October.

Zucchini is an annual plant. The edible parts are the flowers, fruit and seeds.

zucchini
Photo: Diego Delso · CC BY-SA 3.0

Zucchini through the year

JanFebMarAprMayJunJulAugSepOctNovDec
Indoor sowing
Transplanting
Outdoor sowing
Harvest
15913172125293337414549
  • indoor sowing
  • transplanting
  • outdoor sowing
  • harvest

In short

Outdoor sowing
from May to June
weeks 21 to 23
the window opens a week after the last frost
Indoor sowing
in April
weeks 15 to 18
the window opens five weeks before the last frost
Transplanting
from May to June
weeks 21 to 23
the window opens a week after the last frost
Sowing depth
2 cm
Spacing in the row
50 to 90 cm
90 to 180 cm between rows
Germination
10 to 12 days
Germination temperature
18 to 21 °C
Days to maturity
40 to 50 days
Harvest
from July to October
weeks 27 to 40

The last frost is not on the same day everywhere, so the recorded weeks are a guide and not a date.

Growing conditions

🪨
Soil
loamy
🧪
pH
5.5 to 6.5
☀️
Sun
full sun
💧
Water
moderate water
❄️
Frost
does not tolerate frost
🌱
Nutrients
a moderate feeder
🔁
Crop rotation
no sooner than the fourth year
📏
Height
30 to 90 cm

Companions in the bed

Companion planting is tradition and not an agronomic claim. What is recorded is which pairs sources recommend and which they advise against.

bean cited
onion cited
sweet corn cited
  • “Cited” means the pair is named by one source or two.

Pests and diseases

Listed here is every problem for which the sources name this plant as a host. The problems are not listed in order of how common they are.

Aphids

pest
Signs
Colonies of small aphids sit on the shoot tips and the underside of the leaves. The leaf curls and puckers, and sticky honeydew is left on everything below. The viruses they carry are more dangerous than the feeding itself.
Prevention
Go easy on nitrogen, because soft sappy growth is what aphids are looking for. Encourage the predators (ladybirds, lacewings, parasitic wasps). Use a reflective mulch, which puts them off settling, and a strong jet of water to knock the colony off the tips.

Blossom end rot

disorder
Signs
At the blossom end of the fruit there is a watery, then dark, sunken and leathery patch. It is not a disease and does not pass from plant to plant, it is a sign that calcium never reached the fruit.
Prevention
Even moisture in the soil is the main measure: mulch and deep watering instead of a little and often. No excess nitrogen. Lime after a soil test, so that the calcium in the soil is available at all.
What to do
Remove the affected fruit. The next fruits come clean once the moisture steadies. A calcium spray gives temporary relief at best and does not replace watering.

Powdery mildew

disease
Signs
A white, floury coating spreads over the leaves, first on the lower and older ones. The leaf under it yellows and dries up. The fruit stays small, because the plant loses leaf surface.
Prevention
Plant resistant varieties, leave an airy spacing and sun, and clear the debris at the end of the season. Unlike most fungi it is not helped by wet foliage, since it spreads in heat and high air humidity, in a dry summer too.

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Related plants

The plants below are in the same botanical family (Cucurbitaceae).

Sources about the plant: GBIF Backbone Taxonomy, KGZS Zavod Ljubljana, KGZS Zavod Nova Gorica, NC State Extension Plant Toolbox, Royal Horticultural Society, Semenarna Ljubljana, Smernice za strokovno utemeljeno gnojenje (Mihelič et al., MKGP 2011), Utah State University Extension, Wikidata. Checked between 14 and 28 August 2026. The problem descriptions also draw on: Clemson Cooperative Extension, KGZS, UF/IFAS Extension, University of Maryland Extension, University of Wisconsin-Madison Division of Extension.