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When to Plant Broccoli Rabe in Powell County, MT

Powell County, Montana Zone 4b May

This month in Powell County, Montana

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 6
Avg. first frost September 8
Soil temp (4") 40°F
Watering Moderate
Pest pressure Low
Daylight 14.8 hrs
  1. Sow broccoli rabe where they'll grow

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

A few tasks this May that'll pay off in June
  • Transplants going out: broccoli rabe
  • Fall sowing: broccoli rabe

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Broccoli rabe (rapini) is a brassica grown for its slightly bitter, nutty-flavored florets, leaves, and stems. It is a staple in Italian cooking.

Powell County, Montana is in USDA Zone 4b. The average last spring frost is June 6 and the first fall frost is September 8, giving you a growing season of approximately 94 days.

At an elevation of 5,514 feet, Powell County receives approximately 22.9 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Broccoli Rabe to ensure they mature before fall.

Powell County, MT (Zone 4b) Very short season
94 days
Last Spring Frost June 6
94 growing days
First Fall Frost September 8
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Powell County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jul 1 – Aug 5
Recommended (50%) ✓ Fits season (17 days to spare)
Start indoors: Apr 25 Transplant: Jun 6 🍅 Harvest: Jul 18 – Aug 22
Safe Start (90%) ✓ Fits season (26 days to spare)
Start indoors: May 9 Transplant: Jun 20 🍅 Harvest: Aug 1 – 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.

Soil Compatibility in Powell County

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

Soil pH

Your soil pH (6.5–8.2) overlaps with Broccoli Rabe's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Broccoli Rabe

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 Rabe

2
successive plantings in your 94-day season

Sow every 4.6 weeks. Last sowing by Jul 10 to harvest before frost.

For a dedicated fall crop, sow by Jun 16.

Plant Water Budget

Plant needs
0.8″/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 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Broccoli Rabe

Broccoli Rabe needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Broccoli Rabe Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 3.5" 1.4" 2.1" 🚿 Regular watering
Jul 3.5" 2.1" 1.4" 💧 Light watering
Aug 3.5" 2.2" 1.3" 💧 Light watering
Sep 3.5" 1.8" 1.7" 💧 Light watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

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

Broccoli Rabe 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 Rabe needs ~650 GDD — county provides 1,222 GDD Excellent fit

Broccoli Rabe Planting Timeline — Powell County, MT

Broccoli Rabe Planting Calendar

Activity When Date Range
Start Indoors April 25 Apr 25 – May 9
Transplant Outdoors June 6 Jun 6 – Jun 20
Direct Sow May 30 May 30 – Jun 20
Harvest July 18 Jul 18 – Aug 22
Fall Sowing June 16 Jun 16 – Jun 30

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 Fall Sowing
July Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Natural rainfall sufficient

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

94 days in Powell County

Growing Tips for Broccoli Rabe in Powell County

Direct sow Broccoli Rabe outdoors after June 06 in Powell County when soil has warmed and frost danger has passed.

Common pests for Broccoli Rabe in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in spring or fall. Harvest when small yellow flower buds first appear but before they open. Cut the main shoot first to encourage side shoots.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Broccoli Rabe in Powell County, MT?

Powell County is in Zone 4b with an average last frost of June 6. Plan your Broccoli Rabe planting based on this frost date — see the calendar above for exact timing.

What planting zone is Powell County, MT?

Powell County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is June 6 and first fall frost is September 8.

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Your Powell County Garden Planner — Free

A 24-page printable planner built for Powell County (Zone 4b). 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 Powell County, MT. 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.