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When to Plant Broccoli in Butte County, ID

Butte County, Idaho Zone 5a May

Butte County, Idaho gardeners: here's your May plan

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost June 1
Avg. first frost September 14
Soil temp (4") 34°F
Watering Moderate
Pest pressure Low
Daylight 14.5 hrs
  1. Direct-sow broccoli

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

To set up a strong June, finish these tasks
  • Transplants going out: 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.

Butte County, Idaho is in USDA Zone 5a. The average last spring frost is June 1 and the first fall frost is September 14, giving you a growing season of approximately 105 days.

At an elevation of 7,254 feet, Butte County receives approximately 24 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.

Butte County, ID (Zone 5a) Short season
105 days
Last Spring Frost June 1
105 growing days
First Fall Frost September 14

Butte County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Jul 23 – Sep 3
Recommended (50%) ✓ Fits season (0 days to spare)
Start indoors: Apr 27 Transplant: Jun 1 🍅 Harvest: Aug 3 – Sep 14
Safe Start (90%) ✓ Fits season (5 days to spare)
Start indoors: May 13 Transplant: Jun 17 🍅 Harvest: Aug 19 – Sep 30

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 Butte County

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

Soil pH

Your soil pH (6.8–8.4) is more alkaline than Broccoli prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Broccoli.

How to Plant Broccoli

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

How Much Broccoli to Grow

1-2 lbs
Average yield per plant
3
Plants per person
7.5 sq ft
Space per person

For a family of 4, plant approximately 12 broccoli plants in about 30 sq ft. In Butte County's 105-day season, you'll have plenty of time for a full harvest. Plan your garden layout →

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 45 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 4.3" 1.9" 2.4" 🚿 Regular watering
Jul 4.3" 1.9" 2.4" 🚿 Regular watering
Aug 4.3" 2.7" 1.6" 💧 Light watering
Sep 4.3" 1.7" 2.6" 🚿 Regular watering
Oct 2.2" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Butte 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 1,365 GDD Excellent fit

Broccoli Planting Timeline — Butte County, ID

Broccoli Planting Calendar

Activity When Date Range
Start Indoors April 27 Apr 27 – May 11
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 18 May 18 – Jun 8
Harvest August 3 Aug 3 – Sep 14
Fall Sowing July 6 Jul 6 – Jul 20

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

Month-by-Month Timeline

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

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: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

105 days in Butte County

Growing Tips for Broccoli in Butte County

Direct sow Broccoli outdoors after June 01 in Butte 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.

Butte County receives only 24" of rain annually. Broccoli needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Butte County, ID?

Butte County is in Zone 5a with an average last frost of June 1. Plan your Broccoli planting based on this frost date — see the calendar above for exact timing.

What planting zone is Butte County, ID?

Butte County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is June 1 and first fall frost is September 14.

🌱

Your Butte County Garden Planner — Free

A 24-page printable planner built for Butte County (Zone 5a). 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 Butte County, ID. 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.