Thyme · Wheaton, Illinois, United States
When to plant thyme in Wheaton
Main outdoor window
13 May - 3 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
11 Aug - 10 Sep
If you plant at the start of the window.
The average last frost. Half of all years are later than this.
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
1-22 Mar
Eight weeks before your last frost, under cover or on a windowsill.
Plant
13 May - 3 Jun
Delayed by a soil-warming estimate derived from historical air temperatures. The frost-only date would be 26 Apr. Measure your soil before planting.
Harvest
11 Aug - 10 Sep
Thyme through the year
Against the frost risk in Wheaton
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.
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.
| Month | Average low | Average high | Frost days |
|---|---|---|---|
| January | -9.8°C (14.4°F)14.4°F (-9.8°C) | -1.5°C (29.3°F)29.3°F (-1.5°C) | 29.4 |
| February | -8.2°C (17.3°F)17.3°F (-8.2°C) | 1.1°C (33.9°F)33.9°F (1.1°C) | 26.6 |
| March | -2.4°C (27.6°F)27.6°F (-2.4°C) | 7.7°C (45.9°F)45.9°F (7.7°C) | 23.1 |
| April | 2.6°C (36.7°F)36.7°F (2.6°C) | 14.5°C (58.1°F)58.1°F (14.5°C) | 8.7 |
| May | 8.8°C (47.8°F)47.8°F (8.8°C) | 20.7°C (69.3°F)69.3°F (20.7°C) | 0.3 |
| June | 14.7°C (58.5°F)58.5°F (14.7°C) | 26.3°C (79.3°F)79.3°F (26.3°C) | 0.0 |
| July | 17.6°C (63.8°F)63.8°F (17.6°C) | 28.7°C (83.6°F)83.6°F (28.7°C) | 0.0 |
| August | 17.2°C (63°F)63°F (17.2°C) | 28.3°C (83°F)83°F (28.3°C) | 0.0 |
| September | 12.9°C (55.2°F)55.2°F (12.9°C) | 24.7°C (76.4°F)76.4°F (24.7°C) | 0.0 |
| October | 5.9°C (42.7°F)42.7°F (5.9°C) | 17°C (62.6°F)62.6°F (17°C) | 3.2 |
| November | -0.7°C (30.7°F)30.7°F (-0.7°C) | 8.4°C (47.2°F)47.2°F (8.4°C) | 18.0 |
| December | -6.3°C (20.6°F)20.6°F (-6.3°C) | 1.4°C (34.5°F)34.5°F (1.4°C) | 27.5 |
For thyme, 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 thyme 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 thyme
Use the calendar to plan ahead, then check the conditions in your own garden.
- Measure the soil at sowing depth. Aim for at least 15°C (59°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.
- Check mature size, drainage and cultivar suitability before choosing a permanent position. A suitable planting window does not guarantee long-term survival or fruiting.
Keep common thyme compact and out of wet ground
Cuttings, divisions or named plants can be more dependable than seed, which germinates unevenly. Use a growing medium that drains freely and check the base after prolonged rain rather than watering on a fixed schedule.
Clip leafy tips and leave the woody framework with living growth. Light trimming helps prevent a sprawling, bare centre; cutting the entire plant back to leafless stems is a different and riskier operation. Leave some flowers if pollinator visits are part of your aim.
What to record this season
Did trimming preserve a compact leafy mound or expose an increasingly bare centre? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.
Further reading: NC State Extension: Thymus vulgaris . 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
Cuttings, divisions or named plants can be more dependable than seed, which germinates unevenly. Use a growing medium that drains freely and check the base after prolonged rain rather than watering on a fixed schedule.
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. Thyme are timed from 8 weeks before that frost for an indoor start, with planting out 0 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.
Growing thyme in Wheaton
Can I grow thyme 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 thyme in Wheaton?
Aim for 13 May - 3 Jun in an average year. If you would rather not gamble on the weather, wait until 13 May - 3 Jun - by then frost has finished in nine years out of ten.
Can I plant thyme earlier in Wheaton?
The historical frost estimate is 26 Apr. For Thyme, an air-temperature model estimates soil warmth of about 15°C (59°F) around 13 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 thyme be ready to harvest in Wheaton?
The estimated period is 11 Aug - 10 Sep, based on 90 to 120 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 thyme 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.