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When to Plant Jostaberry in Garfield County, MT

Garfield County, Montana Zone 4b May

May in the garden — Garfield County, Montana

We've pulled the most time-sensitive tasks for Garfield County, Montana this May and put them front and centre. Tackle them in order.

Avg. last frost May 16
Avg. first frost September 21
Soil temp (4") 28°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
Before June arrives, get these ready
  • Transplants going out: jostaberry

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Jostaberry is a thornless hybrid of black currant and gooseberry, producing medium-sized, dark berries with a complex, tart-sweet flavor. It is vigorous and disease-resistant.

Garfield County, Montana is in USDA Zone 4b. The average last spring frost is May 16 and the first fall frost is September 21, giving you a growing season of approximately 128 days.

At an elevation of 8,464 feet, Garfield County receives approximately 18.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Jostaberry to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Jostaberry successfully. Mulch heavily to conserve soil moisture.

Garfield County, MT (Zone 4b) Short season
128 days
Last Spring Frost May 16
128 growing days
First Fall Frost September 21

Garfield County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: Jun 7
Recommended (50%) ✓ Fits season
Transplant: Jun 13
Safe Start (90%) ✓ Fits season
Transplant: Jun 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 Garfield County

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

Soil pH

Your soil pH (6.3–7.9) is more alkaline than Jostaberry prefers (6.0–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Jostaberry.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Jostaberry.

How to Plant Jostaberry

48"
Between Plants
72"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 934 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Jostaberry

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

Month Jostaberry Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 4.3" 2.3" 2" 💧 Light watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 1.5" 2.8" 🚿 Regular watering
Aug 4.3" 2" 2.3" 🚿 Regular watering
Sep 4.3" 1.8" 2.5" 🚿 Regular watering
Oct 1.5" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Garfield County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Jostaberry 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.

Jostaberry needs ~9,809 GDD — county provides 1,376 GDD May not mature

Jostaberry Planting Timeline — Garfield County, MT

Jostaberry Planting Calendar

Activity When Date Range
Transplant Outdoors June 13 Jun 13 – Jun 27

· 48" apart · Rows 72" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

730–1095 days

🧪 Soil pH

Needs 6–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

128 days in Garfield County

Growing Tips for Jostaberry in Garfield County

Direct sow Jostaberry outdoors after May 16 in Garfield County when soil has warmed and frost danger has passed.

Your 128.0-day growing season in Garfield County is tight for Jostaberry (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.

Garfield County receives only 19" of rain annually. Jostaberry needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Plant in rich, well-drained soil. No special pruning required beyond removing old wood. Self-fertile but yields improve with a second bush. Berries ripen midsummer.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Jostaberry in Garfield County, MT?

Garfield County is in Zone 4b with an average last frost of May 16. Plan your Jostaberry planting based on this frost date — see the calendar above for exact timing.

What planting zone is Garfield County, MT?

Garfield County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 16 and first fall frost is September 21.

🌱

Your Garfield County Garden Planner — Free

A 24-page printable planner built for Garfield 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 Garfield 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.