Blog

When to Plant Broccoli in Slope County, ND

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.

Slope County, North Dakota is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 24, giving you a growing season of approximately 132 days.

At an elevation of 1,230 feet, Slope County receives approximately 31.4 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Broccoli to ensure they mature before fall.

Slope County, ND (Zone 4a) Short season
132 days
Last Spring Frost May 15
132 growing days
First Fall Frost September 24

Slope County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Start indoors: Mar 31 Transplant: May 12 🍅 Harvest: Jul 14 – Aug 25
Recommended (50%) ✓ Fits season (27 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Jul 17 – Aug 28
Safe Start (90%) ✓ Fits season (22 days to spare)
Start indoors: Apr 20 Transplant: Jun 1 🍅 Harvest: Aug 3 – Sep 14

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
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 424 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Broccoli needs ~750 GDD — county provides 1,320 GDD Excellent fit

Broccoli Planting Timeline โ€” Slope County, ND

Broccoli Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 โ€“ Apr 17
Transplant Outdoors May 15 May 15 โ€“ May 29
Direct Sow May 8 May 8 โ€“ May 29
Fall Sowing July 2 Jul 2 โ€“ Jul 16
Harvest July 17 Jul 17 โ€“ Aug 28

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
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 4a

Growing Season

132 days

Growing Tips for Slope 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 Slope County, ND?

Slope County is in Zone 4a with an average last frost of May 15. Plan your Broccoli planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Slope County, ND?

Slope County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 24.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Slope 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 Slope County, ND. Local conditions may vary. Last updated: April 2026.