When to Plant Bok Choy in Winnebago County, IL
Bok choy is a Chinese cabbage variety with crisp white stalks and dark green leaves. It is a fast-growing cool-season crop ideal for stir-fries and soups.
Winnebago County, Illinois is in USDA Zone 5a. The average last spring frost is April 26 and the first fall frost is October 12, giving you a growing season of approximately 169 days.
At an elevation of 1,318 feet, Winnebago County receives approximately 38.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Bok Choy during the growing season.
Winnebago County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-7.3
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Winnebago County
How your county's soil matches Bok Choy's growing requirements.
Soil pH
Your soil pH (6.3–7.3) is within Bok Choy's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Winnebago County is excellent for Bok Choy — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.1%) — Bok Choy will thrive.
How to Plant Bok Choy
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Bok Choy
Sow every 4.6 weeks. Last sowing by Aug 13 to harvest before frost.
For a dedicated fall crop, sow by Aug 03.
Plant Water Budget
Monthly Watering Guide for Bok Choy
Bok Choy needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Bok Choy Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 3" | 3.9" | 0" | ✅ Rainfall sufficient |
| May | 3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jun | 3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 3" | 4" | 0" | ✅ Rainfall sufficient |
| Aug | 3" | 3.8" | 0" | ✅ Rainfall sufficient |
| Sep | 3" | 3.6" | 0" | ✅ Rainfall sufficient |
| Oct | 3" | 2.8" | 0.2" | 💧 Light watering |
| Nov | — | 2.8" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Winnebago County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Bok Choy Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Bok Choy Planting Timeline — Winnebago County, IL
Bok Choy Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 22 | Mar 22 – Apr 5 |
| Transplant Outdoors | April 26 | Apr 26 – May 10 |
| Direct Sow | April 12 | Apr 12 – May 3 |
| Harvest | June 7 | Jun 7 – Jul 12 |
| Fall Sowing | August 3 | Aug 3 – Aug 17 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.7"/week · Natural rainfall sufficient
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5a
📆 Growing Season
169 days in Winnebago County
Growing Tips for Bok Choy in Winnebago County
Direct sow Bok Choy outdoors after April 26 in Winnebago County when soil has warmed and frost danger has passed.
Your generous 169.0-day season in Winnebago County allows multiple plantings of Bok Choy. Sow every 20.0 days for continuous harvest.
Common pests for Bok Choy in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in spring or fall for best results. Keep soil consistently moist. Harvest whole heads or cut outer leaves for a cut-and-come-again approach.
Companion Planting
Good Companions
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Bok Choy in Other Locations
Frequently Asked Questions
When should I plant Bok Choy in Winnebago County, IL?
Winnebago County is in Zone 5a with an average last frost of April 26. Plan your Bok Choy planting based on this frost date — see the calendar above for exact timing.
What planting zone is Winnebago County, IL?
Winnebago County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 26 and first fall frost is October 12.
Plan Your Garden with Confidence
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