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When to Plant Broccoli in Billings County, ND

Billings County, North Dakota Zone 4a May

Your May gardening checklist

A quick May briefing for Billings County, North Dakota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 19
Avg. first frost September 21
Soil temp (4") 55°F
Watering Moderate
Pest pressure Low
Daylight 14.9 hrs
  1. Move broccoli into the garden

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

  2. Outdoor sowing time: broccoli

    These tolerate cool soil, so you're not gambling by sowing now.

Coming up in June — start thinking about
  • Starting indoors: broccoli
  • Fall sowing: broccoli

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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.

Billings County, North Dakota is in USDA Zone 4a. The average last spring frost is May 19 and the first fall frost is September 21, giving you a growing season of approximately 125 days.

At an elevation of 894 feet, Billings County receives approximately 26.2 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Broccoli to ensure they mature before fall.

Billings County, ND (Zone 4a) Short season
125 days
Last Spring Frost May 19
125 growing days
First Fall Frost September 21
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Billings County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (20 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jul 16 – Aug 27
Recommended (50%) ✓ Fits season (20 days to spare)
Start indoors: Apr 7 Transplant: May 19 🍅 Harvest: Jul 21 – Sep 1
Safe Start (90%) ✓ Fits season (18 days to spare)
Start indoors: Apr 21 Transplant: Jun 2 🍅 Harvest: Aug 4 – Sep 15

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 Billings County

How your county's soil matches Broccoli's growing requirements.

Soil pH

Your soil pH (6.5–7.4) overlaps with Broccoli's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Billings County is excellent for Broccoli — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (4.0%). Annual compost additions will help Broccoli.

How to Plant Broccoli

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Broccoli

2
successive plantings in your 125-day season

Sow every 6.9 weeks. Last sowing by Jun 23 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 160 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Broccoli

Broccoli needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Broccoli Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 1.6" 2.7" 🚿 Regular watering
Jul 4.3" 2.3" 2" 💧 Light watering
Aug 4.3" 2.9" 1.4" 💧 Light watering
Sep 4.3" 2.4" 1.9" 💧 Light watering
Oct 2" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Billings County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Broccoli 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.

Broccoli needs ~975 GDD — county provides 1,625 GDD Excellent fit

Broccoli Planting Timeline — Billings County, ND

Broccoli Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 19 May 19 – Jun 2
Direct Sow May 12 May 12 – Jun 2
Harvest July 21 Jul 21 – Sep 1
Fall Sowing June 29 Jun 29 – Jul 13

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

125 days in Billings County

Growing Tips for Broccoli in Billings County

Direct sow Broccoli outdoors after May 19 in Billings County when soil has warmed and frost danger has passed.

Common pests for Broccoli 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 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

Check more plant combinations with our Companion Planting Checker →

🌾 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 35°F, under 50% humidity.

Isolate 1/2 mile from other brassicas. Biennial — must overwinter roots.

Frequently Asked Questions

When should I plant Broccoli in Billings County, ND?

Billings County is in Zone 4a with an average last frost of May 19. Plan your Broccoli planting based on this frost date — see the calendar above for exact timing.

What planting zone is Billings County, ND?

Billings County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 19 and first fall frost is September 21.

🌱

Your Billings County Garden Planner — Free

A 24-page printable planner built for Billings 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.

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

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.