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When to Plant Cranberries in Judith Basin County, MT

Judith Basin County, Montana Zone 4b May

Your May planting checklist for Judith Basin County, Montana

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
A few tasks this May that'll pay off in June
  • Transplants going out: cranberries

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Cranberries are low-growing, vine-like shrubs that produce tart red berries in fall. They grow in acidic, boggy conditions and are surprisingly easy to cultivate.

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 Cranberries to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Cranberries 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) ✓ Fits season
Transplant: Jun 13
Recommended (50%) ✓ Fits season
Transplant: Jun 20
Safe Start (90%) ✓ Fits season
Transplant: Jul 7

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 Cranberries's growing requirements.

Soil pH

Your soil pH (6.5–8.2) is more alkaline than Cranberries prefers (4.0–5.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

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

How to Plant Cranberries

36"
Between Plants
48"
Between Rows

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.6″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 1,112 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Cranberries

Cranberries needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Cranberries 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 6.5" 2.2" 4.3" 🚿 Regular watering
Jun 6.5" 1.3" 5.2" 🚿 Regular watering
Jul 6.5" 1.7" 4.8" 🚿 Regular watering
Aug 6.5" 1.9" 4.6" 🚿 Regular watering
Sep 6.5" 1.4" 5.1" 🚿 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.

Cranberries 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.

Cranberries needs ~9,125 GDD — county provides 1,190 GDD May not mature

Cranberries Planting Timeline — Judith Basin County, MT

Cranberries Planting Calendar

Activity When Date Range
Transplant Outdoors June 20 Jun 20 – Jul 4

· 36" apart · Rows 48" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June Transplant Outdoors
July Transplant Outdoors
August
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

730–1095 days

🧪 Soil pH

Needs 4–5.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

119 days in Judith Basin County

Growing Tips for Cranberries in Judith Basin County

Direct sow Cranberries 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 Cranberries (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.

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

General growing tips

Create an acidic, consistently moist bed with peat moss. Cranberries do not need to be flooded to grow; flooding is only used for commercial harvesting. Mulch with sand in early spring.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

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

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

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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.