When to Plant Broccoli in Wheaton, Illinois, United States

Step by step in Wheaton

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

8-29 Mar

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

Sow for autumn

19 Jun - 10 Jul

Counting back 104 days from your first frost so the crop matures in time.

Plant out

12 Apr - 3 May

Two weeks before your last frost.

Harvest

11 Jun - 11 Jul

Frost tolerance

Half-hardy

Damaged below

-6°C (21.2°F)

Days to maturity

60–90

Min soil temp

7°C (44.6°F)

Spacing

45 cm

Sowing depth

12 mm (0.5 in)

Sun

Full

Broccoli through the year

Against the frost risk in Wheaton

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Broccoli

Frost risk Start indoors Autumn sowing Plant out Harvest Today

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
Month	Average low	Average high	Frost 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 broccoli, 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 broccoli 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 broccoli

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

Measure the soil at sowing depth. Aim for at least 7°C (44.6°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.

Distinguish heading broccoli from sprouting broccoli

Start a manageable number of plants and transplant them before they become badly restricted in small cells. Space them for their mature canopy and keep the root zone evenly moist.

Harvest heading broccoli while the buds are still closed. Waiting for a larger head after the buds loosen can trade tenderness for open flowers.

Some varieties produce useful side shoots after the main head is cut. Keep a healthy plant only if its variety and remaining season justify the bed space; inspect for caterpillars before harvesting.

Growing in a container

Broccoli needs more space than its seedling suggests. Use a suitable large container for a compact variety rather than crowding several full-size plants into one pot.

What to record this season

When was the main head ready, and did useful side shoots follow? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.

Further reading: RHS calabrese growing guide . General crop guidance; local dates on this site are calculated separately. Source checked 19 September 2026 by Safe to Plant; this is not an expert review.

The RHS guide is written for UK growing conditions. Its cultivation advice does not validate the dates calculated for your town.

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

Why these dates

Start a manageable number of plants and transplant them before they become badly restricted in small cells. Space them for their mature canopy and keep the root zone evenly moist.

Protect tender growth from frost and wait for suitable growing warmth. The catalog cold-damage figure is a reference, not a guarantee: duration, wind, plant age and acclimatisation affect damage.

This calendar uses frost-relative offsets as a starting point. Broccoli are timed from 7 weeks before that frost for an indoor start, with planting out 2 weeks before 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 60 to 90 days to maturity for this crop counted from planting out. That margin is what decides whether a late sowing is worth attempting.

See every crop timed for Wheaton →

Nearby

Broccoli 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 Courgettes tender Sweet peppers tender Carrots hardy Cucumbers tender Green beans tender Peas hardy Garlic very hardy Chilli peppers tender Sweetcorn tender

Growing broccoli in Wheaton

Can I grow broccoli 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 broccoli in Wheaton?

Aim for 12 Apr - 3 May in an average year. If you would rather not gamble on the weather, wait until 28 Apr - 19 May - by then frost has finished in nine years out of ten.

When might broccoli be ready to harvest in Wheaton?

The estimated period is 11 Jun - 11 Jul, based on 60 to 90 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 broccoli tolerate?