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When to Plant Celeriac in Pierce County, WA

Pierce County, Washington Zone 8b May

Your May planting checklist for Pierce County, Washington

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

Avg. last frost April 13
Avg. first frost October 30
Soil temp (4") 70°F
Watering Moderate
Pest pressure High
Daylight 14.9 hrs
  1. Begin indoor sowing: celeriac

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

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Celeriac is a celery relative grown for its knobby, flavorful root rather than its stalks. It has a rich celery flavor and is excellent roasted, mashed, or in soups.

Pierce County, Washington is in USDA Zone 8b. The average last spring frost is April 13 and the first fall frost is October 30, giving you a growing season of approximately 200 days.

At an elevation of 168 feet, Pierce County receives approximately 48.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Celeriac to ensure they mature before fall.

Pierce County, WA (Zone 8b) Long season
200 days
Last Spring Frost April 13
200 growing days
First Fall Frost October 30

Pierce County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Start indoors: Feb 28 Transplant: Apr 4 🍅 Harvest: Jul 18 – Aug 22
Recommended (50%) ✓ Fits season (60 days to spare)
Start indoors: Mar 9 Transplant: Apr 13 🍅 Harvest: Jul 27 – Aug 31
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Apr 11 Transplant: May 16 🍅 Harvest: Aug 29 – Oct 3

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 Pierce County

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

Soil pH

Your soil pH (5.4–6.2) is more acidic than Celeriac prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — Celeriac will thrive.

How to Plant Celeriac

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

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

Plant Water Budget

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

Monthly Watering Guide for Celeriac

Celeriac needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Celeriac Needs Rainfall You Supplement Action
Jan 6.8" 0" ❄️ Dormant
Feb 5.7" 0" ❄️ Dormant
Mar 4.4" 0" ❄️ Dormant
Apr 3.9" 4.1" 0" ✅ Rainfall sufficient
May 3.9" 2.8" 1.1" 💧 Light watering
Jun 3.9" 2" 1.9" 💧 Light watering
Jul 3.9" 0.9" 3" 🚿 Regular watering
Aug 3.9" 0.9" 3" 🚿 Regular watering
Sep 3.9" 2" 1.9" 💧 Light watering
Oct 3.9" 4.7" 0" ✅ Rainfall sufficient
Nov 7.8" 0" ❄️ Dormant
Dec 6.8" 0" ❄️ Dormant

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

Celeriac 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.

Celeriac needs ~1,348 GDD — county provides 2,450 GDD Excellent fit

Celeriac Planting Timeline — Pierce County, WA

Celeriac Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors April 13 Apr 13 – Apr 27
Direct Sow March 30 Mar 30 – Apr 20
Harvest July 27 Jul 27 – Aug 31
Fall Sowing August 21 Aug 21 – Sep 4

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Natural rainfall sufficient

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 8b

📆 Growing Season

200 days in Pierce County

Growing Tips for Celeriac in Pierce County

Direct sow Celeriac outdoors after April 13 in Pierce County when soil has warmed and frost danger has passed.

Common pests for Celeriac in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Remove side roots as they develop to encourage a single large bulb. Harvest after a light frost for best flavor.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Parsnip

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Celeriac in Pierce County, WA?

Pierce County is in Zone 8b with an average last frost of April 13. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pierce County, WA?

Pierce County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 13 and first fall frost is October 30.

🌱

Your Pierce County Garden Planner — Free

A 24-page printable planner built for Pierce 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 Pierce 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.