When to Plant Brussels Sprouts in St. Clair County, IL
Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.
St. Clair County, Illinois is in USDA Zone 6b. The average last spring frost is April 2 and the first fall frost is November 2, giving you a growing season of approximately 214 days.
At an elevation of 711 feet, St. Clair County receives approximately 34.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Brussels Sprouts during the growing season.
St. Clair County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7.3
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.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Brussels Sprouts Planting Timeline — St. Clair County, IL
Brussels Sprouts Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 26 | Feb 26 – Mar 12 |
| Transplant Outdoors | April 2 | Apr 2 – Apr 16 |
| Direct Sow | March 19 | Mar 19 – Apr 9 |
| Fall Sowing | August 24 | Aug 24 – Sep 7 |
| Harvest | July 2 | Jul 2 – Aug 27 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
90–130 days
Soil pH
6 – 7.5
USDA Zone
Zone 6b
Growing Season
214 days
Growing Tips for St. Clair County
Start seeds indoors 12-14 weeks before first fall frost. Stake tall plants to prevent toppling. Remove lower leaves as sprouts develop to improve air circulation.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Brussels Sprouts in Other Locations
Frequently Asked Questions
When should I plant Brussels Sprouts in St. Clair County, IL?
St. Clair County is in Zone 6b with an average last frost of April 2. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Clair County, IL?
St. Clair County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 2 and first fall frost is November 2.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help St. Clair County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.
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