Courgette · Wheaton, Illinois, United States

When to plant courgettes in Wheaton

Main outdoor window

29 May - 12 Jun

A climate estimate. Check your soil, forecast and cultivar.

Timed from last spring frost

26 April

In Wheaton, on your chosen risk.

Ready to pick

13-28 Jul

If you plant at the start of the window.

The average last frost. Half of all years are later than this.

Estimated soil-warming check. The historical frost estimate is 10 May. An air-temperature model suggests soil suitable for courgettes may warm to about 18°C (64.4°F) around 29 May. This is a planning estimate, not a soil measurement. The calendar uses the later date; measure your bed at sowing depth and check the forecast before planting.

Step by step in Wheaton

Download these planting dates (.ics)

Import into Apple Calendar, Google Calendar or Outlook. Dates use the selected risk level and are planning estimates, not frost alerts.

Each window is a planning range. Check the forecast, soil and cultivar before planting; a later date is not automatically safer in hot or wet conditions.

Start indoors

5-19 Apr

Three weeks before your last frost, under cover or on a windowsill.

Sow direct

29 May - 12 Jun

Delayed by a soil-warming estimate derived from historical air temperatures. The frost-only date would be 10 May. Measure your soil before planting.

Plant out

29 May - 12 Jun

Delayed by a soil-warming estimate derived from historical air temperatures. The frost-only date would be 10 May. Measure your soil before planting.

Harvest

13-28 Jul

Sow in succession. A single sowing gives you a single glut. Sow a short row every 28 days through the window above and you get a steady supply instead.
Frost tolerance
Tender
Damaged below
0°C (32°F)
Days to maturity
45–60
Min soil temp
18°C (64.4°F)
Spacing
90 cm
Sowing depth
25 mm (1 in)
Sun
Full

Courgettes through the year

Against the frost risk in Wheaton

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Courgettes

Frost risk Start indoors Sow direct Plant out Harvest Today
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Seasonal context

Rainfall and the growing season in Wheaton

May has the highest average precipitation (121 mm); January has the lowest (44 mm). Compare this pattern with the planting windows and your water supply.

Jan 44 mm
Feb 51 mm
Mar 63 mm
Apr 94 mm
May 121 mm
Jun 112 mm
Jul 100 mm
Aug 105 mm
Sep 87 mm
Oct 91 mm
Nov 58 mm
Dec 58 mm

During wetter months, check that beds and containers drain after heavy rain. During drier months, plan how you will keep seeds and new transplants watered. Monthly averages can hide long dry spells and intense storms; they do not show soil moisture, humidity or this week's weather.

Source: NASA POWER, corrected MERRA-2 precipitation, 2001–2020. Values are approximate monthly totals, including the water equivalent of snow, from the nearest 0.5° × 0.625° grid cell. This reference period differs from the temperature record. Rainfall provides context and does not change the calculated planting dates. Method and limitations.

Monthly growing conditions in Wheaton

Compare the planting window with the local temperature pattern. These are historical monthly averages, not this year's forecast or measured soil temperatures. Average frost days do not tell you whether a particular night will freeze.

NASA POWER climate averages, 1995–2024
MonthAverage lowAverage highFrost days
January -9.8°C (14.4°F) -1.5°C (29.3°F) 29.4
February -8.2°C (17.3°F) 1.1°C (33.9°F) 26.6
March -2.4°C (27.6°F) 7.7°C (45.9°F) 23.1
April 2.6°C (36.7°F) 14.5°C (58.1°F) 8.7
May 8.8°C (47.8°F) 20.7°C (69.3°F) 0.3
June 14.7°C (58.5°F) 26.3°C (79.3°F) 0.0
July 17.6°C (63.8°F) 28.7°C (83.6°F) 0.0
August 17.2°C (63°F) 28.3°C (83°F) 0.0
September 12.9°C (55.2°F) 24.7°C (76.4°F) 0.0
October 5.9°C (42.7°F) 17°C (62.6°F) 3.2
November -0.7°C (30.7°F) 8.4°C (47.2°F) 18.0
December -6.3°C (20.6°F) 1.4°C (34.5°F) 27.5

For courgettes, also check drainage, sunlight and cultivar requirements. See the rainfall context above; humidity, irrigation and local pest pressure are not calculated.

Local growing check

Before choosing courgettes for Wheaton

  • May is the wettest month in the rainfall grid, averaging about 121 mm. Check how your own bed drains and plan watering around actual soil moisture; monthly rain totals are not an irrigation schedule.

The temperature and rainfall tables on this page show the underlying climate estimates. How these suitability checks work · Record what happens in your garden.

Before you plant courgettes

Use the calendar to plan ahead, then check the conditions in your own garden.

  • Measure the soil at sowing depth. Aim for at least 18°C (64.4°F); the calendar estimates soil warmth from air temperatures and cannot measure your bed.
  • Check the local overnight forecast before planting out. Delay planting or keep protection ready if frost is forecast, even after the historical last-frost date.
  • Harden off plants raised indoors: gradually expose them to outdoor light, wind and temperature before their final move into the bed.
  • Use the maturity range on your seed packet when choosing a variety. Cold, short days and transplant stress can make harvest later than the calendar estimate.

Give courgettes room and pick regularly

Check whether the variety is a compact bush or a climbing type before planning the bed. Vigorous plants need considerably more room than a seedling suggests.

Choose fertile soil in sun and keep water available as fruits develop. In a humid growing season, disease-resistant varieties and space for air movement are useful precautions.

Pick fruits regularly while small if you want courgettes rather than large marrows. Inspect underneath the leaves, where fruit can quickly become oversized.

Growing in a container

Choose a compact variety and a large pot with drainage holes; check watering often during fruiting.

Further reading: RHS courgette growing guide . General crop guidance; local dates on this site are calculated separately. Source checked 18 September 2026 by Safe to Plant; this is not an expert review.

How the dates are calculated and their limits · Keep a growing record · Report a local discrepancy

Why these dates

Check whether the variety is a compact bush or a climbing type before planning the bed. Vigorous plants need considerably more room than a seedling suggests.

Check the named variety and local forecast before exposing young growth. The catalog cold-damage figure is a reference, not a guarantee: plant age, acclimatisation, wind and the duration of a freeze affect damage.

This calendar uses frost-relative offsets as a starting point. Courgettes are timed from 3 weeks before that frost for an indoor start, with planting out 2 weeks after it, and this page simply resolves those offsets against the frost date computed for Wheaton.

The calendar also applies a soil-warming estimate derived from historical air temperatures. Where that estimate is later than the frost-based date, it delays the window. Soil in your own garden can warm earlier or later; a thermometer at sowing depth is a better final check. Cold, wet conditions can slow germination and increase decay risk.

The median frost-free season here is 179 days, against 45 to 60 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.

See every crop timed for Wheaton →

Nearby

Courgettes in places close by

Naperville 10 km Schaumburg 19 km Bolingbrook 19 km Hoffman Estates 20 km Aurora 21 km Elgin 24 km

Also in Wheaton

Other vegetables to time

Tomatoes tender Lettuce half hardy Potatoes half hardy Sweet peppers tender Carrots hardy Cucumbers tender Green beans tender Peas hardy Garlic very hardy Chilli peppers tender Sweetcorn tender

Growing courgettes in Wheaton

Can I grow courgettes in Wheaton?

The calendar estimates a planting window, not a guarantee of success. May is the wettest month in the rainfall grid, averaging about 121 mm. Check how your own bed drains and plan watering around actual soil moisture; monthly rain totals are not an irrigation schedule.

When should I plant courgettes in Wheaton?

Aim for 29 May - 12 Jun in an average year. If you would rather not gamble on the weather, wait until 28 May - 11 Jun - by then frost has finished in nine years out of ten.

Can I plant courgettes earlier in Wheaton?

The historical frost estimate is 10 May. For Courgettes, an air-temperature model estimates soil warmth of about 18°C (64.4°F) around 29 May. This is not a soil measurement or a forecast. Check your bed at sowing depth; cold, wet conditions can slow growth and increase decay risk.

When might courgettes be ready to harvest in Wheaton?

The estimated period is 13-28 Jul, based on 45 to 60 days from the modeled planting date. Cultivar, planting material and growing conditions can change this interval; check the plant as well as the calendar.

How much frost will courgettes tolerate?

Check the named variety and local forecast before exposing young growth. The catalog cold-damage figure is a reference, not a guarantee: plant age, acclimatisation, wind and the duration of a freeze affect damage.