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When to Plant Basil in Mineral County, MT

Mineral County, Montana Zone 6a May

Top priorities for Mineral County, Montana gardeners in May

Your garden in Mineral County, Montana is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 30
Avg. first frost September 20
Soil temp (4") 44°F
Watering High
Pest pressure Low
Daylight 14.9 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.

Mineral County, Montana is in USDA Zone 6a. The average last spring frost is May 30 and the first fall frost is September 20, giving you a growing season of approximately 113 days.

At an elevation of 5,389 feet, Mineral County receives approximately 12.5 inches of rainfall annually with predominantly loam soil. Summer highs average 84°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.

Mineral County, MT (Zone 6a) Short season
113 days
Last Spring Frost May 30
113 growing days
First Fall Frost September 20
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Mineral County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 26 Transplant: May 28 🍅 Harvest: Jul 23 – Sep 24
Recommended (50%) ✗ May not fit
Start indoors: Apr 11 Transplant: Jun 13 🍅 Harvest: Aug 8 – Oct 10
Safe Start (90%) ✗ May not fit
Start indoors: May 1 Transplant: Jul 3 🍅 Harvest: Aug 28 – Oct 30

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 Mineral County

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

Soil pH

Your soil pH (6.7–7.7) is more alkaline than Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Basil.

Organic Matter

Organic matter is moderate (2.4%). 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 113-day season

Sow every 5.7 weeks. Last sowing by Jul 07 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.5″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 381 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 0.9" 0" ❄️ Dormant
Feb 0.7" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1.1" 0" ❄️ Dormant
May 2.6" 1.6" 1" 💧 Light watering
Jun 2.6" 0.9" 1.7" 🚿 Regular watering
Jul 2.6" 1.2" 1.4" 🚿 Regular watering
Aug 2.6" 1.3" 1.3" 🚿 Regular watering
Sep 2.6" 1.1" 1.5" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 0.9" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Mineral 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 ~812 GDD — county provides 1,469 GDD Excellent fit

Basil Planting Timeline — Mineral County, MT

Basil Planting Calendar

Activity When Date Range
Start Indoors April 11 Apr 11 – Apr 25
Transplant Outdoors June 13 Jun 13 – Jun 27
Direct Sow June 6 Jun 6 – Jun 27
Harvest August 8 Aug 8 – Oct 10

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · 1-2 times/week

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

113 days in Mineral County

Growing Tips for Basil in Mineral County

Direct sow Basil outdoors after May 30 in Mineral 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 Mineral County, MT?

Mineral County is in Zone 6a with an average last frost of May 30. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mineral County, MT?

Mineral County, Montana is in USDA Hardiness Zone 6a. The average last spring frost is May 30 and first fall frost is September 20.

🌱

Your Mineral County Garden Planner — Free

A 24-page printable planner built for Mineral County (Zone 6a). 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 Mineral 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.