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When to Plant Celeriac in Roy, UT

Roy, UT Zone 7a June

This month in Roy, UT

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 26
Avg. first frost September 21
Soil temp (4") 56°F
Watering High
Pest pressure High
Daylight 15 hrs
  1. Start celeriac indoors

    You're about 14 weeks out from your last frost — the perfect window to get these germinating indoors.

A few tasks this June that'll pay off in July
  • Fall sowing: celeriac

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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.

Roy, Utah is in USDA Zone 7a. The average last spring frost is May 26 and the first fall frost is September 21, giving you a growing season of approximately 118 days.

At an elevation of 6,211 feet, Weber County receives approximately 18.4 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Celeriac during the growing season. With low rainfall, drip irrigation is essential for growing Celeriac successfully. Mulch heavily to conserve soil moisture.

Roy, UT (Zone 7a) Short season
118 days
Last Spring Frost May 26
118 growing days
First Fall Frost September 21

Roy Soil Profile

Soil Type

Loam

Soil pH

6.6-7.7

Drainage

Well Drained

Celeriac Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 2 Transplant: May 7 🍅 Harvest: Aug 20 – Sep 24
Recommended (50%) ✗ May not fit
Start indoors: Apr 21 Transplant: May 26 🍅 Harvest: Sep 8 – Oct 13
Safe Start (90%) ✗ May not fit
Start indoors: May 15 Transplant: Jun 19 🍅 Harvest: Oct 2 – Nov 6

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 Roy

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

Soil pH

Your soil pH (6.6–7.7) is more alkaline than Celeriac prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). 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.

Celeriac Water Budget

Plant needs
0.9″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 309 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

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 1.3" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 3.9" 2.1" 1.8" 💧 Light watering
Jun 3.9" 1.4" 2.5" 🚿 Regular watering
Jul 3.9" 1.5" 2.4" 🚿 Regular watering
Aug 3.9" 2.2" 1.7" 💧 Light watering
Sep 3.9" 1.5" 2.4" 🚿 Regular watering
Oct 1.5" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Weber 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 ~1,595 GDD — county provides 1,711 GDD Good fit

Celeriac Planting Timeline — Roy, UT

Celeriac Planting Calendar

Activity When Date Range
Start Indoors April 21 Apr 21 – May 5
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 12 May 12 – Jun 2
Harvest September 8 Sep 8 – Oct 13
Fall Sowing July 13 Jul 13 – Jul 27

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Only during dry spells

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7a

📆 Growing Season

118 days in Weber County

Growing Tips for Celeriac in Roy

Direct sow Celeriac outdoors after May 26 in Weber County when soil has warmed and frost danger has passed.

Your 118.0-day growing season in Weber County is tight for Celeriac (100.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

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

Weber County receives only 18" of rain annually. Celeriac needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 →

🌱

Your Weber County Garden Planner — Free

A 22-page printable planner built for Weber County (Zone 7a). 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 Weber County, UT. Local conditions may vary. Last updated: June 2026.