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When to Plant Celeriac in Washington County, PA

Washington County, Pennsylvania Zone 6b May

This month in Washington County, Pennsylvania

May is a pivotal month for Washington County, Pennsylvania gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 23
Avg. first frost October 28
Soil temp (4") 64°F
Watering Low
Pest pressure Low
Daylight 14.2 hrs
  1. Start celeriac under lights

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

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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.

Washington County, Pennsylvania is in USDA Zone 6b. The average last spring frost is April 23 and the first fall frost is October 28, giving you a growing season of approximately 188 days.

At an elevation of 1,083 feet, Washington County receives approximately 42.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Celeriac during the growing season.

Washington County, PA (Zone 6b) Moderate season
188 days
Last Spring Frost April 23
188 growing days
First Fall Frost October 28
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Washington County Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (46 days to spare)
Start indoors: Mar 11 Transplant: Apr 15 🍅 Harvest: Jul 29 – Sep 2
Recommended (50%) ✓ Fits season (48 days to spare)
Start indoors: Mar 19 Transplant: Apr 23 🍅 Harvest: Aug 6 – Sep 10
Safe Start (90%) ✓ Fits season (42 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Aug 23 – Sep 27

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 Washington County

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

Soil pH

Your soil pH (5.0–6.3) is more acidic than Celeriac prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.7%). Annual compost additions will help Celeriac.

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
0.9″/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 3" 0" ❄️ Dormant
Feb 3" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 3.9" 3.5" 0.4" 💧 Light watering
May 3.9" 4.2" 0" ✅ Rainfall sufficient
Jun 3.9" 4.3" 0" ✅ Rainfall sufficient
Jul 3.9" 4.1" 0" ✅ Rainfall sufficient
Aug 3.9" 3.8" 0.1" 💧 Light watering
Sep 3.9" 3.7" 0.2" 💧 Light watering
Oct 3.9" 3.5" 0.4" 💧 Light watering
Nov 3.1" 0" ❄️ Dormant
Dec 3.1" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Washington 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 ~1,678 GDD — county provides 2,867 GDD Excellent fit

Celeriac Planting Timeline — Washington County, PA

Celeriac Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors April 23 Apr 23 – May 7
Direct Sow April 9 Apr 9 – Apr 30
Harvest August 6 Aug 6 – Sep 10
Fall Sowing August 19 Aug 19 – Sep 2

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Transplant Outdoors Direct Sow
May Transplant Outdoors
June
July
August Fall Sowing Harvest
September Fall Sowing Harvest
October
November
December
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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 6b

📆 Growing Season

188 days in Washington County

Growing Tips for Celeriac in Washington County

Direct sow Celeriac outdoors after April 23 in Washington 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 Washington County, PA?

Washington County is in Zone 6b with an average last frost of April 23. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washington County, PA?

Washington County, Pennsylvania is in USDA Hardiness Zone 6b. The average last spring frost is April 23 and first fall frost is October 28.

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Your Washington County Garden Planner — Free

A 24-page printable planner built for Washington County (Zone 6b). 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 Washington County, PA. 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.