Zucchini
Courgette, Summer Squash, Italian Marrow, Acorn Squash, American Pumpkin And Summer Squashes, American Pumpkin, Bitter Bottle Gourd, Brazilian Pumpkin, Bush Squash
One of the fastest-producing vegetables. Direct sow 1" deep after last frost. Give each plant 4–6 ft of space. Hand-pollinate if bees are scarce (male flowers open first). Harvest at 6–8" for best flavor. Overgrown zucchini drains plant energy.
- Germination
- 4–10 days
- Soil temperature
- 16–35 °C
- Harvest after sowing
- 45–60 days
- Spacing
- 60–90 cm
When to plant zucchini
Sow outdoors 1–2 weeks after your last spring frost.
Dashed line: typical last spring frost in zone 7 (Apr 5). Zone dates are averages; most of the UK is zone 8–9, central Europe 6–7 and the Baltics and Scandinavia 4–6. In the app, Tomatograph uses your garden's own frost dates.
How to grow zucchini
- 1
Sow
Sow 2–3 seeds 2.5 cm deep per station 1–2 weeks after the last frost, then keep the strongest seedling. Allow about 1 m between plants.
- 2
Water
Water at the base, never over the leaves: powdery mildew is the most common problem. Rich, compost-filled soil keeps plants cropping.
- 3
Help pollination
If small fruit rot at the tip, pollination is poor. Transfer pollen from a male flower to the female flowers with a small brush in the morning.
- 4
Harvest
Check daily once fruiting starts, about 45–60 days after sowing. Cut at 15–20 cm with a short stem; oversized marrows slow the plant down.
Growing conditions
Light
Full sun
Water
High water
Temperature
15–35 °C
Frost tolerance
Frost-sensitive — protect below 0 °C
Days to maturity
55 days
Plant spacing
90 cm
How Tomatograph watches your zucchini
Tomatograph checks your local forecast every morning and only speaks up when one of these applies to your garden.
- Forecast of 2 °C or lowerFrost alert the evening before: cover plants with fleece or bring pots inside.
- 3 days at 35 °C or aboveHeat-wave alert while plants are flowering or fruiting: shade and water early.
- Humidity above 80% for 48 hoursCheck for powdery mildew, which thrives in those conditions.
- Under 5 mm of rain forecast over 3 daysWatering reminder: water deeply at the base, early in the morning.
- Within a week of maturityHarvest-window reminder based on when you planted.
Zucchini questions
- When should I plant zucchini?
- Sow outdoors 1–2 weeks after your last spring frost.
- How long do zucchini seeds take to germinate?
- Usually 4–10 days at a soil temperature of 16–35 °C.
- How long until I can harvest zucchini?
- About 45–60 days after sowing, depending on variety and weather.
- How far apart should I plant zucchini?
- Allow 60–90 cm between plants.
- What grows well with zucchini?
- Good neighbours include corn, pea, nasturtium, borage.
Growing guide written by Tomatograph. Planting figures from openplantdb (CC0 1.0). Zone frost dates are averages from openplantdb (CC0 1.0).