When to Plant Wallflowers 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.

Sow direct

7 Jun - 5 Jul

Six weeks after your last frost.

Move to final position

13 Sep - 11 Oct

20 weeks after your last frost.

In flower

1 Apr - 31 May

Frost tolerance

Very-hardy

Damaged below

-20°C (-4°F)

Days to flowering

300–340

Hardy to

Zone 5a–9a

Min soil temp

13°C (55.4°F)

Spacing

30 cm

Sowing depth

5 mm (0.2 in)

Sun

Full

Wallflowers through the year

Against the frost risk in Wheaton

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Wallflowers

Frost risk Sow direct 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 wallflowers, 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 wallflowers 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 wallflowers

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

Measure the soil at sowing depth. Aim for at least 13°C (55.4°F); the calendar estimates soil warmth from air temperatures and cannot measure your bed.
Frost tolerance does not make saturated or frozen soil suitable for planting. Wait until the bed can be worked without smearing or compacting it.
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.

Keep wallflower roots drained and check its life cycle

Choose a sunny position with very good drainage. Avoid the assumption that extra feeding and frequent watering will improve every plant; soft growth and wet roots can shorten the useful life of a wallflower. Space plants for airflow at their mature width.

After flowering, decide whether seed is wanted or whether to clear tired plants for the next crop. Inspect the base before retaining an old plant for another season. Record which strain produces a good display in your conditions rather than relying on the common name to predict longevity.

What to record this season

Did plants remain healthy after flowering, and was replacing or retaining them more successful? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.

Further reading: NC State Extension: Erysimum cheiri . 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 reference describes plant identity and cultivation. Its regional calendar months and hardiness observations do not validate the calculated dates for another location.

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

Why these dates

Choose a sunny position with very good drainage. Avoid the assumption that extra feeding and frequent watering will improve every plant; soft growth and wet roots can shorten the useful life of a wallflower. Space plants for airflow at their mature width.

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. Wallflowers are timed with planting out 20 weeks after it, and this page simply resolves those offsets against the frost date computed for Wheaton.

Wheaton is zone 5b, within the crop's general range. This is an initial cold-hardiness check; cultivar, exposure, drainage and unusual winters can still change the outcome.

This is a two-season crop, so the dates above describe a sowing in one year and a flowering in the next. The plant spends the winter in the ground as a small rosette, which is why the frost-free season in Wheaton does not limit it the way it would limit a tomato: it is not trying to finish before the cold arrives, it is trying to be well enough rooted to sit through it. Sowing too late is the real risk, because a plant that goes into winter undersized often fails to flower at all the following year.

See every crop timed for Wheaton →

Nearby

Wallflowers 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 flowers to time

Tulips very hardy Daffodils very hardy Dahlias tender Sunflowers tender Crocuses very hardy Peonies very hardy Calendulas hardy Hyacinths very hardy Sweet peas hardy Pansies very hardy Snowdrops very hardy Zinnias tender

Growing wallflowers in Wheaton

Can I grow wallflowers 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 wallflowers in Wheaton?

Aim for 7 Jun - 5 Jul in an average year. If you would rather not gamble on the weather, wait until 23 Jun - 21 Jul - by then frost has finished in nine years out of ten.

When might wallflowers flower in Wheaton?

The estimated period is 1 Apr - 31 May, based on 300 to 340 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 wallflowers tolerate?