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When to Plant Rutabaga in Sonoma County, CA

Sonoma County, California Zone 9b May

Top priorities for Sonoma County, California gardeners in May

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

Avg. last frost February 26
Avg. first frost November 26
Soil temp (4") 76°F
Watering Critical
Pest pressure High
Daylight 14.1 hrs
  1. Harvest rutabaga as they ripen

    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: rutabaga

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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.

Sonoma County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.

At an elevation of 91 feet, Sonoma County receives approximately 31.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 90°F, providing good warmth for Rutabaga during the growing season. Sandy soil warms quickly in spring — great for early planting — but Rutabaga will need more frequent watering and organic matter to retain nutrients.

Sonoma County, CA (Zone 9b) Year-round
273 days
Last Spring Frost February 26
273 growing days
First Fall Frost November 26

Sonoma County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.9-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (166 days to spare)
Transplant: Feb 10 🍅 Harvest: May 5 – Jun 9
Recommended (50%) ✓ Fits season (154 days to spare)
Transplant: Feb 26 🍅 Harvest: May 21 – Jun 25
Safe Start (90%) ✓ Fits season (140 days to spare)
Transplant: Apr 2 🍅 Harvest: Jun 25 – Jul 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 Sonoma County

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

Soil pH

Your soil pH (5.9–7.0) overlaps with Rutabaga's range (6.0–7.5), though not a perfect match.

Soil Texture

Sandy soil in Sonoma County warms quickly in spring but drains fast. Rutabaga will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Rutabaga.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Rutabaga.

How to Plant Rutabaga

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

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Rutabaga

4
successive plantings in your 273-day season

Sow every 9.1 weeks. Last sowing by Aug 18 to harvest before frost.

For a dedicated fall crop, sow by Oct 01.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.5″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 1,268 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 6.2" 0" ❄️ Dormant
Feb 3" 6.8" 0" ✅ Rainfall sufficient
Mar 3" 5.2" 0" ✅ Rainfall sufficient
Apr 3" 2.3" 0.7" 💧 Light watering
May 3" 0.8" 2.2" 🚿 Regular watering
Jun 3" 0.1" 2.9" 🚿 Regular watering
Jul 3" 0" 3" 🚿 Regular watering
Aug 3" 0" 3" 🚿 Regular watering
Sep 3" 0.4" 2.6" 🚿 Regular watering
Oct 3" 1.3" 1.7" 🚿 Regular watering
Nov 3" 2.7" 0.3" 💧 Light watering
Dec 5.2" 0" ❄️ Dormant

Water needs are for active growing months only (Feb–Nov in Sonoma 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 ~1,575 GDD — county provides 4,795 GDD Excellent fit

Rutabaga Planting Timeline — Sonoma County, CA

Rutabaga Planting Calendar

Activity When Date Range
Direct Sow February 5 Feb 5 – Feb 26
Harvest April 30 Apr 30 – Jun 4
Fall Sowing October 1 Oct 1 – Oct 15

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · 1-2 times/week

📅 Days to Maturity

80–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

273 days in Sonoma County

Growing Tips for Rutabaga in Sonoma County

Direct sow Rutabaga outdoors after February 26 in Sonoma County when soil has warmed and frost danger has passed.

Sandy soil in Sonoma County dries quickly — mulch Rutabaga with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

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 Sonoma County, CA?

Sonoma County is in Zone 9b with an average last frost of February 26. Plan your Rutabaga planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sonoma County, CA?

Sonoma County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 26.

🌱

Your Sonoma County Garden Planner — Free

A 24-page printable planner built for Sonoma County (Zone 9b). 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 Sonoma County, CA. 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.