Blog

When to Plant Rutabaga in Jefferson County, WA

Jefferson County, Washington Zone 8b May

What to do in May

A quick May briefing for Jefferson County, Washington gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 14
Avg. first frost October 29
Soil temp (4") 69°F
Watering High
Pest pressure High
Daylight 14.9 hrs
June will be here before you know it — start on
  • First harvests: rutabaga

Instant PDF download. No spam, unsubscribe any time.

Rutabagas are a cross between turnips and cabbage, producing large yellow-fleshed roots with a sweet, mild flavor. They are excellent mashed, roasted, or in stews.

Jefferson County, Washington is in USDA Zone 8b. The average last spring frost is April 14 and the first fall frost is October 29, giving you a growing season of approximately 198 days.

At an elevation of 205 feet, Jefferson County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Rutabaga during the growing season.

Jefferson County, WA (Zone 8b) Moderate season
198 days
Last Spring Frost April 14
198 growing days
First Fall Frost October 29

Jefferson County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (81 days to spare)
Transplant: Apr 6 🍅 Harvest: Jun 29 – Aug 3
Recommended (50%) ✓ Fits season (79 days to spare)
Transplant: Apr 14 🍅 Harvest: Jul 7 – Aug 11
Safe Start (90%) ✓ Fits season (75 days to spare)
Transplant: May 9 🍅 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 Jefferson County

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

Soil pH

Your soil pH (5.7–6.8) overlaps with Rutabaga's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Rutabaga.

Organic Matter

Organic matter is excellent (5.7%) — Rutabaga will thrive.

How to Plant Rutabaga

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 Rutabaga

2
successive plantings in your 198-day season

Sow every 9.1 weeks. Last sowing by Jul 21 to harvest before frost.

For a dedicated fall crop, sow by Aug 20.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 82 gal / 100 sq ft

Monthly Watering Guide for Rutabaga

Rutabaga needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Rutabaga Needs Rainfall You Supplement Action
Jan 6.4" 0" ❄️ Dormant
Feb 4.7" 0" ❄️ Dormant
Mar 3.9" 0" ❄️ Dormant
Apr 3" 2.6" 0.4" 💧 Light watering
May 3" 2.1" 0.9" 💧 Light watering
Jun 3" 1.5" 1.5" 🚿 Regular watering
Jul 3" 0.5" 2.5" 🚿 Regular watering
Aug 3" 0.6" 2.4" 🚿 Regular watering
Sep 3" 1.6" 1.4" 💧 Light watering
Oct 3" 3.5" 0" ✅ Rainfall sufficient
Nov 6.3" 0" ❄️ Dormant
Dec 7.1" 0" ❄️ Dormant

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

Rutabaga 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.

Rutabaga needs ~1,440 GDD — county provides 3,168 GDD Excellent fit

Rutabaga Planting Timeline — Jefferson County, WA

Rutabaga Planting Calendar

Activity When Date Range
Direct Sow March 31 Mar 31 – Apr 21
Harvest June 23 Jun 23 – Jul 28
Fall Sowing August 20 Aug 20 – Sep 3

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

80–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 8b

📆 Growing Season

198 days in Jefferson County

Growing Tips for Rutabaga in Jefferson County

Direct sow Rutabaga outdoors after April 14 in Jefferson County when soil has warmed and frost danger has passed.

Common pests for Rutabaga 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 early summer for fall harvest. Thin seedlings to 6-8 inches apart. Flavor improves significantly after a few light frosts.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Rutabaga in Jefferson County, WA?

Jefferson County is in Zone 8b with an average last frost of April 14. Plan your Rutabaga planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jefferson County, WA?

Jefferson County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 14 and first fall frost is October 29.

🌱

Your Jefferson County Garden Planner — Free

A 24-page printable planner built for Jefferson 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Jefferson 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.