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When to Plant Celeriac in Judith Basin County, MT

Judith Basin County, Montana Zone 4b May

Top priorities for Judith Basin County, Montana gardeners in May

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

Avg. last frost May 23
Avg. first frost September 19
Soil temp (4") 36°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
  1. Time to transplant celeriac

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

  2. Plant celeriac from seed, right in the garden

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Looking ahead to June
  • 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.

Judith Basin County, Montana is in USDA Zone 4b. The average last spring frost is May 23 and the first fall frost is September 19, giving you a growing season of approximately 119 days.

At an elevation of 6,308 feet, Judith Basin County receives approximately 17.7 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.

Judith Basin County, MT (Zone 4b) Short season
119 days
Last Spring Frost May 23
119 growing days
First Fall Frost September 19
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Judith Basin County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 4 Transplant: May 16 🍅 Harvest: Aug 29 – Oct 3
Recommended (50%) ✗ May not fit
Start indoors: Apr 11 Transplant: May 23 🍅 Harvest: Sep 5 – Oct 10
Safe Start (90%) ✗ May not fit
Start indoors: Apr 28 Transplant: Jun 9 🍅 Harvest: Sep 22 – Oct 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 Judith Basin County

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

Soil pH

Your soil pH (6.5–8.2) is more alkaline than Celeriac prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). 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.

Plant 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 350 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 1.2" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 3.9" 2.2" 1.7" 💧 Light watering
Jun 3.9" 1.3" 2.6" 🚿 Regular watering
Jul 3.9" 1.7" 2.2" 🚿 Regular watering
Aug 3.9" 1.9" 2" 🚿 Regular watering
Sep 3.9" 1.4" 2.5" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Judith Basin 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 1,190 GDD Good fit

Celeriac Planting Timeline — Judith Basin County, MT

Celeriac Planting Calendar

Activity When Date Range
Start Indoors April 11 Apr 11 – Apr 25
Transplant Outdoors May 23 May 23 – Jun 6
Direct Sow May 16 May 16 – Jun 6
Harvest September 5 Sep 5 – Oct 10
Fall Sowing June 27 Jun 27 – Jul 11

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
September Harvest
October Harvest
November
December
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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 4b

📆 Growing Season

119 days in Judith Basin County

Growing Tips for Celeriac in Judith Basin County

Direct sow Celeriac outdoors after May 23 in Judith Basin County when soil has warmed and frost danger has passed.

Your 119.0-day growing season in Judith Basin 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.

Judith Basin 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 →

Frequently Asked Questions

When should I plant Celeriac in Judith Basin County, MT?

Judith Basin County is in Zone 4b with an average last frost of May 23. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Judith Basin County, MT?

Judith Basin County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 23 and first fall frost is September 19.

🌱

Your Judith Basin County Garden Planner — Free

A 24-page printable planner built for Judith Basin County (Zone 4b). 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 Judith Basin County, MT. 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.