When to Plant Rocket in Berwyn, Illinois, United States

Step by step in Berwyn

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 for overwintering

29 Aug - 19 Sep

Counting back 59 days from your first frost so the crop matures in time.

Sow direct

25 Mar - 4 Apr

Delayed by a soil-warming estimate derived from historical air temperatures. The frost-only date would be 7 Mar. Measure your soil before planting.

Harvest

24 Apr - 9 May

Sow in succession. A single sowing gives you a single glut. Sow a short row every 10 days through the window above and you get a steady supply instead.

Frost tolerance

Hardy

Damaged below

-7°C (19.4°F)

Days to maturity

30–45

Min soil temp

4.5°C (40.1°F)

Spacing

15 cm

Sowing depth

6 mm (0.2 in)

Sun

Partial

Rocket through the year

Against the frost risk in Berwyn

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Rocket

Frost risk Autumn sowing Sow direct Harvest Today

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.

Jan 47 mm

Feb 53 mm

Mar 62 mm

Apr 93 mm

May 119 mm

Jun 102 mm

Jul 96 mm

Aug 105 mm

Sep 86 mm

Oct 98 mm

Nov 61 mm

Dec 59 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 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.

NASA POWER climate averages, 1995–2024
Month	Average low	Average high	Frost days
January	-4.9°C (23.2°F)	-0.2°C (31.7°F)	25.7
February	-4.5°C (24°F)	0.8°C (33.5°F)	23.6
March	-0.5°C (31°F)	5.1°C (41.2°F)	16.9
April	3.8°C (38.8°F)	10°C (50°F)	2.7
May	8.8°C (47.8°F)	15.2°C (59.3°F)	0.0
June	15.1°C (59.1°F)	21.1°C (70°F)	0.0
July	19.6°C (67.3°F)	24.9°C (76.8°F)	0.0
August	20°C (68.1°F)	25.1°C (77.1°F)	0.0
September	16.4°C (61.5°F)	22°C (71.6°F)	0.0
October	9.9°C (49.7°F)	15.6°C (60°F)	0.0
November	3.4°C (38.2°F)	8.5°C (47.3°F)	5.5
December	-1.8°C (28.9°F)	2.7°C (36.8°F)	18.4

For rocket, 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 rocket 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 rocket

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

Measure the soil at sowing depth. Aim for at least 4.5°C (40.1°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.

Decide between salad rocket and perennial wild rocket

Sow small quantities where you can keep the surface moist. Crowded seedlings can be taken as young leaves, while plants retained longer need room to develop.

Warm, dry weather encourages flowering and stronger leaves. Choose a cooler slot or some light shade in hot conditions rather than assuming that rapid germination means a long harvest.

Take young leaves regularly and compare flavour as the plants age. Plan the next small sowing before the old batch becomes coarse or flowers.

Growing in a container

Rocket is useful in accessible salad containers. A series of small sowings is usually easier to use than one pot allowed to become a dense, flowering clump.

What to record this season

How long did each small sowing remain tender before flowering? Add the cultivar, sowing date and conditions to your growing record so you can compare next season.

Further reading: RHS rocket 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

Sow small quantities where you can keep the surface moist. Crowded seedlings can be taken as young leaves, while plants retained longer need room to develop.

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. Rocket are timed for direct sowing 4 weeks before it, and this page simply resolves those offsets against the frost date computed for Berwyn.

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 227 days, against 30 to 45 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.

See every crop timed for Berwyn →

Nearby

Rocket in places close by

Cicero 3 km Oak Park 4 km Oak Lawn 16 km Skokie 21 km Des Plaines 22 km Evanston 23 km

Also in Berwyn

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 rocket in Berwyn

Can I grow rocket 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 rocket in Berwyn?

Aim for 25 Mar - 4 Apr in an average year. If you would rather not gamble on the weather, wait until 25 Mar - 4 Apr - by then frost has finished in nine years out of ten.

Can I plant rocket earlier in Berwyn?

The historical frost estimate is 7 Mar. For Rocket, an air-temperature model estimates soil warmth of about 4.5°C (40.1°F) around 25 Mar. 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 rocket be ready to harvest in Berwyn?

The estimated period is 24 Apr - 9 May, based on 30 to 45 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 rocket tolerate?