When to Plant Broccoli in Mackinac County, MI
Broccoli is a nutrient-dense cool-season crop that produces large central heads followed by smaller side shoots. It is one of the most popular garden vegetables.
Mackinac County, Michigan is in USDA Zone 4b. The average last spring frost is May 12 and the first fall frost is October 10, giving you a growing season of approximately 151 days.
At an elevation of 1,335 feet, Mackinac County receives approximately 35.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Broccoli to ensure they mature before fall.
Mackinac County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-6.9
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.
Plant Water Budget
Broccoli Planting Timeline — Mackinac County, MI
Broccoli Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 31 | Mar 31 – Apr 14 |
| Transplant Outdoors | May 12 | May 12 – May 26 |
| Direct Sow | May 5 | May 5 – May 26 |
| Fall Sowing | July 18 | Jul 18 – Aug 1 |
| Harvest | July 14 | Jul 14 – Aug 25 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing Harvest |
| August | Fall Sowing Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
60–90 days
Soil pH
6 – 7
USDA Zone
Zone 4b
Growing Season
151 days
Growing Tips for Mackinac County
Start seeds indoors 6-8 weeks before last frost. Provide consistent moisture to prevent hollow stems. Harvest heads before yellow flowers appear.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Isolate 1/2 mile from other brassicas. Biennial — must overwinter roots.
Broccoli in Other Locations
Frequently Asked Questions
When should I plant Broccoli in Mackinac County, MI?
Mackinac County is in Zone 4b with an average last frost of May 12. Plan your Broccoli planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mackinac County, MI?
Mackinac County, Michigan is in USDA Hardiness Zone 4b. The average last spring frost is May 12 and first fall frost is October 10.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Mackinac County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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