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When to Plant Broccoli in Clay 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.

Clay County, Minnesota is in USDA Zone 3b. The average last spring frost is May 11 and the first fall frost is September 30, giving you a growing season of approximately 142 days.

At an elevation of 1,220 feet, Clay County receives approximately 35.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Broccoli to ensure they mature before fall.

Clay County, MN (Zone 3b) Short season
142 days
Last Spring Frost May 11
142 growing days
First Fall Frost September 30

Clay County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (40 days to spare)
Start indoors: Mar 21 Transplant: May 2 🍅 Harvest: Jul 4 – Aug 15
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Jul 13 – Aug 24
Safe Start (90%) ✓ Fits season (39 days to spare)
Start indoors: Apr 11 Transplant: May 23 🍅 Harvest: Jul 25 – Sep 5

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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Broccoli needs ~750 GDD — county provides 1,420 GDD Excellent fit

Broccoli Planting Timeline โ€” Clay County, MN

Broccoli Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 โ€“ Apr 13
Transplant Outdoors May 11 May 11 โ€“ May 25
Direct Sow May 4 May 4 โ€“ May 25
Fall Sowing July 8 Jul 8 โ€“ Jul 22
Harvest July 13 Jul 13 โ€“ Aug 24

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June โ€”
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 3b

Growing Season

142 days

Growing Tips for Clay 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 Clay County, MN?

Clay County is in Zone 3b with an average last frost of May 11. Plan your Broccoli planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Clay County, MN?

Clay County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 11 and first fall frost is September 30.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Clay County gardeners in Zone 3b organize planting dates, track what's growing, and never miss a planting window.

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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 Clay County, MN. Local conditions may vary. Last updated: April 2026.