Purple sprouting broccoli · Evanston, Illinois, United States
When to plant purple sprouting broccoli in Evanston
Main outdoor window
13 Jun - 11 Jul
A climate estimate. Check your soil, forecast and cultivar.
Timed from last spring frost
4 April
In Evanston, on your chosen risk.
Ready to pick
1 Feb - 30 Apr
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 Evanston
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.
Sow direct
13 Jun - 11 Jul
Ten weeks after your last frost.
Harvest
1 Feb - 30 Apr
Purple sprouting broccoli through the year
Against the frost risk in Evanston
Seasonal context
Rainfall and the growing season in Evanston
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 Evanston
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 purple sprouting 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 purple sprouting broccoli for Evanston
- 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 purple sprouting 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.
- Frost tolerance does not make saturated or frozen soil suitable for planting. Wait until the bed can be worked without smearing or compacting it.
- 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.
Plan for repeated shoots and, where relevant, overwintering
Allow enough space and time for a substantial plant before cropping. Support plants if wind or a top-heavy canopy makes them unstable.
Cut usable shoots while the buds remain closed and keep checking for further side shoots. Regular picking and healthy leaves are more useful than waiting for each shoot to become a large head.
What to record this season
How long did the plant occupy the bed before the first usable shoots? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.
Further reading: RHS broccoli 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. Use its cultivation advice with local cultivar and seasonal guidance; its calendar months are not worldwide recommendations.
How the dates are calculated and their limits · Keep a growing record · Report a local discrepancy
Why these dates
Allow enough space and time for a substantial plant before cropping. Support plants if wind or a top-heavy canopy makes them unstable.
Cold tolerance varies with cultivar, plant age, acclimatisation and the duration of a freeze. A plant surviving frost does not mean its leaves, heads, flowers or developing crop will remain undamaged. Check the forecast and the variety's local advice.
This calendar uses frost-relative offsets as a starting point. Purple sprouting broccoli are timed for direct sowing 10 weeks after it, and this page simply resolves those offsets against the frost date computed for Evanston.
The median frost-free season here is 227 days, against 220 to 300 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Nearby
Purple sprouting broccoli in places close by
Also in Evanston
Other vegetables to time
Growing purple sprouting broccoli in Evanston
Can I grow purple sprouting broccoli in Evanston?
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 purple sprouting broccoli in Evanston?
Aim for 13 Jun - 11 Jul in an average year. If you would rather not gamble on the weather, wait until 26 Jun - 24 Jul - by then frost has finished in nine years out of ten.
When might purple sprouting broccoli be ready to harvest in Evanston?
The estimated period is 1 Feb - 30 Apr, based on 220 to 300 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 purple sprouting broccoli tolerate?
Cold tolerance varies with cultivar, plant age, acclimatisation and the duration of a freeze. A plant surviving frost does not mean its leaves, heads, flowers or developing crop will remain undamaged. Check the forecast and the variety's local advice.