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When to Plant Broccoli Rabe in Johnson County, WY

Johnson County, Wyoming Zone 5a May

Your May game plan for Johnson County, Wyoming

We've pulled the most time-sensitive tasks for Johnson County, Wyoming this May and put them front and centre. Tackle them in order.

Avg. last frost May 17
Avg. first frost September 21
Soil temp (4") 30°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Transplant broccoli rabe outside

    Your last frost (May 17) has passed. These warm-season crops can handle outdoor soil now.

  2. Outdoor sowing time: broccoli rabe

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

June prep starts now
  • Starting indoors: broccoli rabe
  • First harvests: 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.

Johnson County, Wyoming is in USDA Zone 5a. The average last spring frost is May 17 and the first fall frost is September 21, giving you a growing season of approximately 127 days.

At an elevation of 8,281 feet, Johnson County receives approximately 23.7 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Broccoli Rabe to ensure they mature before fall.

Johnson County, WY (Zone 5a) Short season
127 days
Last Spring Frost May 17
127 growing days
First Fall Frost September 21

Johnson County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (47 days to spare)
Start indoors: Apr 8 Transplant: May 13 🍅 Harvest: Jun 24 – Jul 29
Recommended (50%) ✓ Fits season (50 days to spare)
Start indoors: Apr 12 Transplant: May 17 🍅 Harvest: Jun 28 – Aug 2
Safe Start (90%) ✓ Fits season (45 days to spare)
Start indoors: May 3 Transplant: Jun 7 🍅 Harvest: Jul 19 – Aug 23

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 Johnson County

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

Soil pH

Your soil pH (6.8–7.8) overlaps with Broccoli Rabe's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Broccoli Rabe.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Broccoli Rabe.

How to Plant Broccoli Rabe

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

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

Succession Planting Broccoli Rabe

3
successive plantings in your 127-day season

Sow every 4.6 weeks. Last sowing by Jul 23 to harvest before frost.

For a dedicated fall crop, sow by Jul 13.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 348 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 1.8" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 3.5" 2.8" 0.7" 💧 Light watering
Jun 3.5" 1.6" 1.9" 🚿 Regular watering
Jul 3.5" 2.3" 1.2" 💧 Light watering
Aug 3.5" 2.5" 1" 💧 Light watering
Sep 3.5" 2.1" 1.4" 💧 Light watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Johnson 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 ~538 GDD — county provides 1,365 GDD Excellent fit

Broccoli Rabe Planting Timeline — Johnson County, WY

Broccoli Rabe Planting Calendar

Activity When Date Range
Start Indoors April 12 Apr 12 – Apr 26
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 3 May 3 – May 24
Harvest June 28 Jun 28 – Aug 2
Fall Sowing July 13 Jul 13 – Jul 27

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 Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · 1-2 times/week

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

127 days in Johnson County

Growing Tips for Broccoli Rabe in Johnson County

Direct sow Broccoli Rabe outdoors after May 17 in Johnson 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 Johnson County, WY?

Johnson County is in Zone 5a with an average last frost of May 17. Plan your Broccoli Rabe planting based on this frost date — see the calendar above for exact timing.

What planting zone is Johnson County, WY?

Johnson County, Wyoming is in USDA Hardiness Zone 5a. The average last spring frost is May 17 and first fall frost is September 21.

🌱

Your Johnson County Garden Planner — Free

A 24-page printable planner built for Johnson 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 Johnson County, WY. 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.