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When to Plant Broccoli in Hennepin County, MN

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.

Hennepin County, Minnesota is in USDA Zone 4a. The average last spring frost is April 23 and the first fall frost is October 9, giving you a growing season of approximately 169 days.

At an elevation of 694 feet, Hennepin County receives approximately 36.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Broccoli to ensure they mature before fall.

Hennepin County, MN (Zone 4a) Moderate season
169 days
Last Spring Frost April 23
169 growing days
First Fall Frost October 9

Hennepin County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (65 days to spare)
Start indoors: Mar 6 Transplant: Apr 17 🍅 Harvest: Jun 19 – Jul 31
Recommended (50%) ✓ Fits season (64 days to spare)
Start indoors: Mar 12 Transplant: Apr 23 🍅 Harvest: Jun 25 – Aug 6
Safe Start (90%) ✓ Fits season (61 days to spare)
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Jul 15 – Aug 26

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

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 580 gal / 100 sq ft
Broccoli needs ~862 GDD — county provides 1,943 GDD Excellent fit

Broccoli Planting Timeline โ€” Hennepin County, MN

Broccoli Planting Calendar

Activity When Date Range
Start Indoors March 12 Mar 12 โ€“ Mar 26
Transplant Outdoors April 23 Apr 23 โ€“ May 7
Direct Sow April 16 Apr 16 โ€“ May 7
Fall Sowing July 17 Jul 17 โ€“ Jul 31
Harvest June 25 Jun 25 โ€“ Aug 6

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

169 days

Growing Tips for Hennepin 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

  • Tomatoes
  • Strawberries

Level Up Your Garden

๐ŸŒพ Save Your Own Broccoli Seeds
Life Cycle Biennial
Pollination Cross-Pollinated (insects)
How to Collect Allow plants to flower 2nd year; collect dry pods.
Storage Store airtight; viable 5 years at 35ยฐF, under 50% humidity.

Isolate 1/2 mile from other brassicas. Biennial โ€” must overwinter roots.

Frequently Asked Questions

When should I plant Broccoli in Hennepin County, MN?

Hennepin County is in Zone 4a with an average last frost of April 23. Plan your Broccoli planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Hennepin County, MN?

Hennepin County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is April 23 and first fall frost is October 9.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Hennepin County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Hennepin County, MN. Local conditions may vary. Last updated: April 2026.