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When to Plant Basil in Beaverhead County, MT

Beaverhead County, Montana Zone 5a May

Your May game plan for Beaverhead County, Montana

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

Avg. last frost June 10
Avg. first frost September 12
Soil temp (4") 31°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
A few tasks this May that'll pay off in June
  • Transplants going out: basil
  • Direct-sowing: basil

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Basil is a fragrant warm-season herb essential to Italian and Thai cuisines. It comes in many varieties including sweet, Thai, purple, and lemon types.

Beaverhead County, Montana is in USDA Zone 5a. The average last spring frost is June 10 and the first fall frost is September 12, giving you a growing season of approximately 94 days.

At an elevation of 7,645 feet, Beaverhead County receives approximately 15.7 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Basil to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Basil successfully. Mulch heavily to conserve soil moisture.

Beaverhead County, MT (Zone 5a) Very short season
94 days
Last Spring Frost June 10
94 growing days
First Fall Frost September 12
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Beaverhead County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 12 Transplant: Jun 14 🍅 Harvest: Aug 9 – Oct 11
Recommended (50%) ✗ May not fit
Start indoors: Apr 22 Transplant: Jun 24 🍅 Harvest: Aug 19 – Oct 21
Safe Start (90%) ✗ May not fit
Start indoors: May 4 Transplant: Jul 6 🍅 Harvest: Aug 31 – Nov 2

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 Beaverhead County

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

Soil pH

Your soil pH (6.8–7.8) is more alkaline than Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Basil.

How to Plant Basil

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Basil

2
successive plantings in your 94-day season

Sow every 5.7 weeks. Last sowing by Jun 29 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Basil

Basil needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Basil Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.8" 0" ❄️ Dormant
May 1.9" 0" ❄️ Dormant
Jun 2.6" 1.1" 1.5" 🚿 Regular watering
Jul 2.6" 1.3" 1.3" 🚿 Regular watering
Aug 2.6" 1.6" 1" 💧 Light watering
Sep 2.6" 1.3" 1.3" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

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

Basil 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.

Basil needs ~625 GDD — county provides 940 GDD Excellent fit

Basil Planting Timeline — Beaverhead County, MT

Basil Planting Calendar

Activity When Date Range
Start Indoors April 22 Apr 22 – May 6
Transplant Outdoors June 24 Jun 24 – Jul 8
Direct Sow June 17 Jun 17 – Jul 8
Harvest August 19 Aug 19 – Oct 21

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors
June Transplant Outdoors Direct Sow
July Transplant Outdoors Direct Sow
August Harvest
September Harvest
October Harvest
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

94 days in Beaverhead County

Growing Tips for Basil in Beaverhead County

Direct sow Basil outdoors after June 10 in Beaverhead County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors or direct sow after last frost. Pinch flower buds to extend leaf production. Harvest leaves from the top down, cutting just above a leaf pair.

Companion Planting

Good Companions

Avoid Planting Near

  • Rue
  • Sage

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Basil Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let flower spikes dry brown on the plant.
Storage Store airtight; viable 5 years at 35°F, under 45% humidity.

Isolate 150 ft between varieties. Different basil species can cross.

Frequently Asked Questions

When should I plant Basil in Beaverhead County, MT?

Beaverhead County is in Zone 5a with an average last frost of June 10. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Beaverhead County, MT?

Beaverhead County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 10 and first fall frost is September 12.

🌱

Your Beaverhead County Garden Planner — Free

A 24-page printable planner built for Beaverhead County (Zone 5a). 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 Beaverhead 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.