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When to plant Celeriac in Phillips County County,

For Celeriac in Phillips County County, the safe spring window opens around May 11 and closes around June 1. Last expected frost is May 18, first fall frost September 21, giving a 126-day growing season. A second sowing from June 29 to July 13 extends the harvest into fall.

When to Plant Celeriac in Phillips County, MT

Phillips County, Montana Zone 3b June

Your June gardening checklist

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Phillips County, Montana.

Avg. last frost May 18
Avg. first frost September 21
Soil temp (4") 44°F
Watering High
Pest pressure High
Daylight 15.9 hrs
  1. Time to start celeriac inside

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

  2. Sow celeriac for an autumn harvest

    A row cover ready in the garage extends your harvest by weeks once the nights turn cold.

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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.

Phillips County, Montana is in USDA Zone 3b. The average last spring frost is May 18 and the first fall frost is September 21, giving you a growing season of approximately 126 days.

At an elevation of 6,886 feet, Phillips County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Celeriac to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Celeriac successfully. Mulch heavily to conserve soil moisture.

Phillips County, MT (Zone 3b) Short season
126 days
Last Spring Frost May 18
126 growing days
First Fall Frost September 21

Phillips County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.6

Drainage

Well Drained

Celeriac Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 31 Transplant: May 12 🍅 Harvest: Aug 25 – Sep 15
Recommended (50%) ✓ Fits season (0 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Aug 31 – Sep 21
Safe Start (90%) ✓ Fits season (1 days to spare)
Start indoors: Apr 19 Transplant: May 31 🍅 Harvest: Sep 13 – Oct 4

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 Phillips County

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

Soil pH

Your soil pH (6.7–7.6) is more alkaline than Celeriac prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Celeriac.

How to Plant Celeriac

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Celeriac Water Budget

Plant needs
0.9″/week
Rainfall provides
0.6″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 359 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1.4" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.6" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 3.9" 2.4" 1.5" 💧 Light watering
Jun 3.9" 1.4" 2.5" 🚿 Regular watering
Jul 3.9" 1.6" 2.3" 🚿 Regular watering
Aug 3.9" 2" 1.9" 💧 Light watering
Sep 3.9" 1.4" 2.5" 🚿 Regular watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Phillips 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 ~1,100 GDD — county provides 1,260 GDD Good fit

Celeriac Planting Timeline — Phillips County, MT

Celeriac Planting Calendar

Activity When Date Range
Start Indoors April 6 Apr 6 – Apr 20
Transplant Outdoors May 18 May 18 – Jun 1
Direct Sow May 11 May 11 – Jun 1
Harvest August 31 Aug 31 – Sep 21
Fall Sowing June 29 Jun 29 – Jul 13

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · 1-2 times/week

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 3b

📆 Growing Season

126 days in Phillips County

Growing Tips for Celeriac in Phillips County

Direct sow Celeriac outdoors after May 18 in Phillips County when soil has warmed and frost danger has passed.

Your 126.0-day growing season in Phillips 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.

Phillips County receives only 19" 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 →

Frequently Asked Questions

When should I plant Celeriac in Phillips County, MT?

Phillips County is in Zone 3b with an average last frost of May 18. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Phillips County, MT?

Phillips County, Montana is in USDA Hardiness Zone 3b. The average last spring frost is May 18 and first fall frost is September 21.

When should I plant Celeriac in Phillips County, ?

In Phillips County, , plant Celeriac after the last frost (around May 18) and before the first frost (around September 21). Best results when soil holds above 50°F.

What growing zone is Phillips County, for Celeriac?

Phillips County sits in USDA Zone 3b. Celeriac grows reliably in zones 3a through 9b, so it's a good fit here.

Can Celeriac grow in Phillips County's climate?

Yes — Celeriac grows well in Phillips County's temperate climate. Phillips County averages a 126-day frost-free season, with last frost around May 18 and first frost around September 21.

🌱

Your Phillips County Garden Planner — Free

A 22-page printable planner built for Phillips County (Zone 3b). 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 Phillips County, MT. Local conditions may vary. Last updated: June 2026.

Sources & credits

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