When to plant Brussels Sprouts in Castleton, IL
Castleton gardeners should plant Brussels Sprouts between April 7 and April 28 in spring. With Castleton's Zone 5b climate (last frost April 21), Brussels Sprouts needs 90–130 days to mature — plant by June 4 for a full harvest. A second sowing from August 3 to August 17 extends the harvest into fall.
When to Plant Brussels Sprouts in Castleton, IL
Top priorities for Stark County, Illinois gardeners in June
Your Stark County, Illinois garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.
Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.
Castleton, Illinois is in USDA Zone 5b. The average last spring frost is April 21 and the first fall frost is October 12, giving you a growing season of approximately 174 days.
At an elevation of 1,071 feet, Stark County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Brussels Sprouts to ensure they mature before fall.
Castleton Soil Profile
Soil Type
Silt Loam
Soil pH
6-6.9
Drainage
Well Drained
Brussels Sprouts 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 Castleton
How your county's soil matches Brussels Sprouts's growing requirements.
Soil pH
Your soil pH (6.0–6.9) is within Brussels Sprouts's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Stark County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.8%) — Brussels Sprouts will thrive.
How to Plant Brussels Sprouts
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Brussels Sprouts Water Budget
Monthly Watering Guide for Brussels Sprouts
Brussels Sprouts needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.
| Month | Brussels Sprouts Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 3.9" | 3.5" | 0.4" | 💧 Light watering |
| May | 3.9" | 4.1" | 0" | ✅ Rainfall sufficient |
| Jun | 3.9" | 4.1" | 0" | ✅ Rainfall sufficient |
| Jul | 3.9" | 3.5" | 0.4" | 💧 Light watering |
| Aug | 3.9" | 3.3" | 0.6" | 💧 Light watering |
| Sep | 3.9" | 2.8" | 1.1" | 💧 Light watering |
| Oct | 3.9" | 2.9" | 1" | 💧 Light watering |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Stark County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Brussels Sprouts 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.
Brussels Sprouts Planting Timeline — Castleton, IL
Brussels Sprouts Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 17 | Mar 17 – Mar 31 |
| Transplant Outdoors | April 21 | Apr 21 – May 5 |
| Direct Sow | April 7 | Apr 7 – Apr 28 |
| Harvest | July 21 | Jul 21 – Sep 15 |
| 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 | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.9"/week · Only during dry spells
📅 Days to Maturity
90–130 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
174 days in Stark County
Growing Tips for Brussels Sprouts in Castleton
Direct sow Brussels Sprouts outdoors after April 21 in Stark County when soil has warmed and frost danger has passed.
Common pests for Brussels Sprouts in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
Brussels Sprouts in Other Locations
When should I plant Brussels Sprouts in Castleton, IL?
In Castleton, IL, plant Brussels Sprouts after the last frost (around April 21) and before the first frost (around October 12). Best results when soil holds above 50°F.
What growing zone is Castleton, IL for Brussels Sprouts?
Castleton sits in USDA Zone 5b. Brussels Sprouts grows reliably in zones 2a through 10b, so it's a good fit here.
Can Brussels Sprouts grow in Castleton's climate?
Yes — Brussels Sprouts grows well in Castleton's temperate climate. Castleton averages a 174-day frost-free season, with last frost around April 21 and first frost around October 12.
Your Stark County Garden Planner — Free
A 22-page printable planner built for Stark County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.