When to Plant Brussels Sprouts in Iron County, WI
Top priorities for Iron County, Wisconsin gardeners in May
Welcome to May in Zone 4a. These are the moves that will have the biggest impact on your growing season.
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Move brussels sprouts into the garden
Frost risk is low now in Iron County, Wisconsin. If you've been covering beds overnight, you can stop.
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Sow brussels sprouts where they'll grow
Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.
Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.
Iron County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 22 and the first fall frost is September 25, giving you a growing season of approximately 126 days.
At an elevation of 841 feet, Iron County receives approximately 32.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Brussels Sprouts to ensure they mature before fall.
Iron County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.9
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 Iron County
How your county's soil matches Brussels Sprouts's growing requirements.
Soil pH
Your soil pH (5.7–6.9) overlaps with Brussels Sprouts's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Iron County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.6%) — Brussels Sprouts will thrive.
How to Plant Brussels Sprouts
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Plant 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 | — | 1.2" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | — | 3" | 0" | ❄️ Dormant |
| May | 3.9" | 3.7" | 0.2" | 💧 Light watering |
| Jun | 3.9" | 3.6" | 0.3" | 💧 Light watering |
| Jul | 3.9" | 3.6" | 0.3" | 💧 Light watering |
| Aug | 3.9" | 3.7" | 0.2" | 💧 Light watering |
| Sep | 3.9" | 3.2" | 0.7" | 💧 Light watering |
| Oct | — | 2.5" | 0" | ❄️ Dormant |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 1.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Iron 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 — Iron County, WI
Brussels Sprouts Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 10 | Apr 10 – Apr 24 |
| Transplant Outdoors | May 22 | May 22 – Jun 5 |
| Direct Sow | May 15 | May 15 – Jun 5 |
| Harvest | August 21 | Aug 21 – Oct 16 |
| Fall Sowing | July 3 | Jul 3 – Jul 17 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.9"/week · Natural rainfall sufficient
📅 Days to Maturity
90–130 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 4a
📆 Growing Season
126 days in Iron County
Growing Tips for Brussels Sprouts in Iron County
Direct sow Brussels Sprouts outdoors after May 22 in Iron County when soil has warmed and frost danger has passed.
Your 126.0-day growing season in Iron County is tight for Brussels Sprouts (90.0-130.0 days to maturity). Start indoors and choose early-maturing varieties.
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
Frequently Asked Questions
When should I plant Brussels Sprouts in Iron County, WI?
Iron County is in Zone 4a with an average last frost of May 22. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.
What planting zone is Iron County, WI?
Iron County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 22 and first fall frost is September 25.
Your Iron County Garden Planner — Free
A 24-page printable planner built for Iron County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.