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When to Plant Turnip in Judith Basin County, MT

Judith Basin County, Montana Zone 4b May

Judith Basin County, Montana gardeners: here's your May plan

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

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. Put turnip seeds straight in the ground

    Your soil is 36°F — warm enough for these to germinate without babying.

Get ahead of June
  • First harvests: turnip
  • Fall sowing: turnip

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Turnips are a fast-growing cool-season root vegetable with edible roots and greens. Baby turnips are sweet and tender while mature ones are more pungent.

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 Turnip to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Turnip 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

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) ✓ Fits season (43 days to spare)
Transplant: May 16 🍅 Harvest: Jun 27 – Aug 1
Recommended (50%) ✓ Fits season (42 days to spare)
Transplant: May 23 🍅 Harvest: Jul 4 – Aug 8
Safe Start (90%) ✓ Fits season (39 days to spare)
Transplant: Jun 9 🍅 Harvest: Jul 21 – Aug 25

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 Turnip's growing requirements.

Soil pH

Your soil pH (6.5–8.2) is more alkaline than Turnip 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 Turnip — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Turnip.

How to Plant Turnip

0.5"
Planting Depth
4"
Between Plants
12"
Between Rows

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

Succession Planting Turnip

3
successive plantings in your 119-day season

Sow every 4.6 weeks. Last sowing by Jul 21 to harvest before frost.

For a dedicated fall crop, sow by Jun 27.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 477 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Turnip

Turnip needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Turnip 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 4.3" 2.2" 2.1" 💧 Light watering
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 1.7" 2.6" 🚿 Regular watering
Aug 4.3" 1.9" 2.4" 🚿 Regular watering
Sep 4.3" 1.4" 2.9" 🚿 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.

Turnip 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.

Turnip needs ~500 GDD — county provides 1,190 GDD Excellent fit

Turnip Planting Timeline — Judith Basin County, MT

Turnip Planting Calendar

Activity When Date Range
Direct Sow May 16 May 16 – Jun 6
Harvest June 27 Jun 27 – Aug 1
Fall Sowing June 27 Jun 27 – Jul 11

Plant 0.5" deep · 4" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

40–60 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 Turnip in Judith Basin County

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

Common pests for Turnip in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

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

General growing tips

Direct sow in early spring or late summer. Harvest when roots are 2-3 inches in diameter for best flavor. Both the roots and the greens are nutritious and edible.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

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

Judith Basin County is in Zone 4b with an average last frost of May 23. Plan your Turnip 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.