Asiatic lily · Berwyn, Illinois, United States
When to plant asiatic lilies in Berwyn
Main outdoor window
17 Nov - 21 Mar
A climate estimate. Check your soil, forecast and cultivar.
Timed from last spring frost
4 April
In Berwyn, on your chosen risk.
First flowers
1 Jun - 31 Jul
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 Berwyn
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.
Plant the bulbs
17 Nov - 21 Mar
Any time the plant is dormant and the ground is neither frozen nor waterlogged: after leaf fall in autumn, or at the end of winter before growth restarts.
In flower
1 Jun - 31 Jul
Asiatic lilies through the year
Against the frost risk in Berwyn
Seasonal context
Rainfall and the growing season in Berwyn
May has the highest average precipitation (119 mm); January has the lowest (47 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 Berwyn
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 | -4.9°C (23.2°F)23.2°F (-4.9°C) | -0.2°C (31.7°F)31.7°F (-0.2°C) | 25.7 |
| February | -4.5°C (24°F)24°F (-4.5°C) | 0.8°C (33.5°F)33.5°F (0.8°C) | 23.6 |
| March | -0.5°C (31°F)31°F (-0.5°C) | 5.1°C (41.2°F)41.2°F (5.1°C) | 16.9 |
| April | 3.8°C (38.8°F)38.8°F (3.8°C) | 10°C (50°F)50°F (10°C) | 2.7 |
| May | 8.8°C (47.8°F)47.8°F (8.8°C) | 15.2°C (59.3°F)59.3°F (15.2°C) | 0.0 |
| June | 15.1°C (59.1°F)59.1°F (15.1°C) | 21.1°C (70°F)70°F (21.1°C) | 0.0 |
| July | 19.6°C (67.3°F)67.3°F (19.6°C) | 24.9°C (76.8°F)76.8°F (24.9°C) | 0.0 |
| August | 20°C (68.1°F)68.1°F (20°C) | 25.1°C (77.1°F)77.1°F (25.1°C) | 0.0 |
| September | 16.4°C (61.5°F)61.5°F (16.4°C) | 22°C (71.6°F)71.6°F (22°C) | 0.0 |
| October | 9.9°C (49.7°F)49.7°F (9.9°C) | 15.6°C (60°F)60°F (15.6°C) | 0.0 |
| November | 3.4°C (38.2°F)38.2°F (3.4°C) | 8.5°C (47.3°F)47.3°F (8.5°C) | 5.5 |
| December | -1.8°C (28.9°F)28.9°F (-1.8°C) | 2.7°C (36.8°F)36.8°F (2.7°C) | 18.4 |
For asiatic lilies, 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 asiatic lilies for Berwyn
- May is the wettest month in the rainfall grid, averaging about 119 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 asiatic lilies
Use the calendar to plan ahead, then check the conditions in your own garden.
- Frost tolerance does not make saturated or frozen soil suitable for planting. Wait until the bed can be worked without smearing or compacting it.
- Check mature size, drainage and cultivar suitability before choosing a permanent position. A suitable planting window does not guarantee long-term survival or fruiting.
Choose early lily colour without assuming strong fragrance
Plant sound scaly bulbs in drained soil with suitable light and room for roots. Keep moisture available during growth without leaving bulbs waterlogged. Inspect stems and leaves for lily beetles and disease where these occur.
Remove spent blooms while retaining green leaves to replenish bulbs. True lilies are highly toxic to cats, including pollen, so choose a different plant where cats may contact the display or cut stems. Keep cultivar labels for comparing return flowering.
What to record this season
Did bulbs return with strong stems, and did the chosen height suit the planting position? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.
Further reading: Lilium – Asiatic hybrids (Asian Lily, Asiatic Hybrid Lilies, Asiatic Lilies, Asiatic Lily, Lilies) | North Carolina Extension Gardener Plant Toolbox . 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. This reference covers the broader plant group; confirm the named form and its specific requirements with the supplier.
How the dates are calculated and their limits · Keep a growing record · Report a local discrepancy
Why these dates
Plant sound scaly bulbs in drained soil with suitable light and room for roots. Keep moisture available during growth without leaving bulbs waterlogged. Inspect stems and leaves for lily beetles and disease where these occur.
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.
Asiatic lilies are planted once and then left in place, so there is no sowing offset to resolve. What matters in Berwyn is the shape of the year: this crop is dormant through the winter and is planted while it sleeps, any time between leaf fall in autumn and the restart of growth in spring, so long as the ground is neither frozen nor waterlogged. That is why the window below spans the cold months rather than sitting in the middle of the growing season.
Berwyn is zone 7a, within the crop's general range. This is an initial cold-hardiness check; cultivar, exposure, drainage and unusual winters can still change the outcome.
Also in Berwyn
Other flowers to time
Growing asiatic lilies in Berwyn
Can I grow asiatic lilies in Berwyn?
The calendar estimates a planting window, not a guarantee of success. May is the wettest month in the rainfall grid, averaging about 119 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 asiatic lilies in Berwyn?
Aim for 17 Nov - 21 Mar in an average year. If you would rather not gamble on the weather, wait until 3 Nov - 3 Apr - by then frost has finished in nine years out of ten.
When might asiatic lilies flower in Berwyn?
The estimated period is 1 Jun - 31 Jul, based on 190 to 230 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 asiatic lilies 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.