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When to Plant Garlic in Richland County, MT

Richland County, Montana Zone 4a May

Your May gardening checklist

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

Avg. last frost May 14
Avg. first frost September 20
Soil temp (4") 36°F
Watering High
Pest pressure Low
Daylight 14.9 hrs

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Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.

Richland County, Montana is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 20, giving you a growing season of approximately 129 days.

At an elevation of 6,414 feet, Richland County receives approximately 13.6 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Garlic to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Garlic successfully. Mulch heavily to conserve soil moisture.

Richland County, MT (Zone 4a) Short season
129 days
Last Spring Frost May 14
129 growing days
First Fall Frost September 20

Richland County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 10 🍅 Harvest: Aug 9 – Oct 4
Recommended (50%) ✗ May not fit
Transplant: May 14 🍅 Harvest: Aug 13 – Oct 8
Safe Start (90%) ✗ May not fit
Transplant: May 30 🍅 Harvest: Aug 29 – Oct 24

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 Richland County

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

Soil pH

Your soil pH (6.5–7.8) overlaps with Garlic's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Garlic.

How to Plant Garlic

1"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 6 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.4″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 79 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Garlic

Garlic needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Garlic Needs Rainfall You Supplement Action
Jan 0.9" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.2" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 2.2" 1.6" 0.6" 💧 Light watering
Jun 2.2" 1" 1.2" 🚿 Regular watering
Jul 2.2" 1" 1.2" 🚿 Regular watering
Aug 2.2" 1.6" 0.6" 💧 Light watering
Sep 2.2" 1.1" 1.1" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

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

Garlic 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.

Garlic needs ~1,650 GDD — county provides 1,290 GDD May not mature

Garlic Planting Timeline — Richland County, MT

Garlic Planting Calendar

Activity When Date Range
Fall Sowing August 9 Aug 9 – Aug 23

Plant 1" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Only during dry spells

📅 Days to Maturity

90–240 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

129 days in Richland County

Growing Tips for Garlic in Richland County

Direct sow Garlic outdoors after May 14 in Richland County when soil has warmed and frost danger has passed.

Your 129.0-day growing season in Richland County is tight for Garlic (90.0-240.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Garlic in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Garlic in Richland County, MT?

Richland County is in Zone 4a with an average last frost of May 14. Plan your Garlic planting based on this frost date — see the calendar above for exact timing.

What planting zone is Richland County, MT?

Richland County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 20.

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Your Richland County Garden Planner — Free

A 24-page printable planner built for Richland County (Zone 4a). 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 Richland 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.