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When to Plant Broccoli Rabe in Island County, WA

Island County, Washington Zone 8b May

May in Island County, Washington — your action list

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

Avg. last frost March 30
Avg. first frost November 3
Soil temp (4") 69°F
Watering High
Pest pressure High
Daylight 15 hrs
  1. Time to start broccoli rabe inside

    Your window is short. These crops want several weeks of indoor growth before they go outside.

  2. It's harvest week for broccoli rabe

    If you can't use it all right away, check the food-preservation section of your planner.

Coming up in June — start thinking about
  • 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.

Island County, Washington is in USDA Zone 8b. The average last spring frost is March 30 and the first fall frost is November 3, giving you a growing season of approximately 218 days.

At an elevation of 9 feet, Island County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Broccoli Rabe during the growing season.

Island County, WA (Zone 8b) Long season
218 days
Last Spring Frost March 30
218 growing days
First Fall Frost November 3

Island County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (144 days to spare)
Start indoors: Feb 15 Transplant: Mar 22 🍅 Harvest: May 3 – Jun 7
Recommended (50%) ✓ Fits season (141 days to spare)
Start indoors: Feb 23 Transplant: Mar 30 🍅 Harvest: May 11 – Jun 15
Safe Start (90%) ✓ Fits season (131 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jun 11 – Jul 16

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 Island County

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

Soil pH

Your soil pH (5.6–6.7) overlaps with Broccoli Rabe's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.3%) — Broccoli Rabe will thrive.

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

6
successive plantings in your 218-day season

Sow every 4.6 weeks. Last sowing by Sep 04 to harvest before frost.

For a dedicated fall crop, sow by Aug 25.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 6.8" 0" ❄️ Dormant
Feb 4.7" 0" ❄️ Dormant
Mar 3.5" 4.5" 0" ✅ Rainfall sufficient
Apr 3.5" 3.7" 0" ✅ Rainfall sufficient
May 3.5" 2.3" 1.2" 💧 Light watering
Jun 3.5" 1.6" 1.9" 🚿 Regular watering
Jul 3.5" 0.7" 2.8" 🚿 Regular watering
Aug 3.5" 0.8" 2.7" 🚿 Regular watering
Sep 3.5" 1.6" 1.9" 🚿 Regular watering
Oct 3.5" 4.2" 0" ✅ Rainfall sufficient
Nov 3.5" 7" 0" ✅ Rainfall sufficient
Dec 7.8" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Island 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 ~688 GDD — county provides 2,997 GDD Excellent fit

Broccoli Rabe Planting Timeline — Island County, WA

Broccoli Rabe Planting Calendar

Activity When Date Range
Start Indoors February 23 Feb 23 – Mar 9
Transplant Outdoors March 30 Mar 30 – Apr 13
Direct Sow March 16 Mar 16 – Apr 6
Harvest May 11 May 11 – Jun 15
Fall Sowing August 25 Aug 25 – Sep 8

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

Month-by-Month Timeline

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

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 8b

📆 Growing Season

218 days in Island County

Growing Tips for Broccoli Rabe in Island County

Direct sow Broccoli Rabe outdoors after March 30 in Island County when soil has warmed and frost danger has passed.

Your generous 218.0-day season in Island County allows multiple plantings of Broccoli Rabe. Sow every 20.0 days for continuous harvest.

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 Island County, WA?

Island County is in Zone 8b with an average last frost of March 30. Plan your Broccoli Rabe planting based on this frost date — see the calendar above for exact timing.

What planting zone is Island County, WA?

Island County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is March 30 and first fall frost is November 3.

🌱

Your Island County Garden Planner — Free

A 24-page printable planner built for Island County (Zone 8b). 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 Island County, WA. 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.