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When to Plant Basil in Montrose County, CO

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.

Montrose County, Colorado is in USDA Zone 6a. The average last spring frost is June 13 and the first fall frost is September 12, giving you a growing season of approximately 91 days.

At an elevation of 6,494 feet, Montrose County receives approximately 18.4 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Basil during the growing season. With low rainfall, drip irrigation is essential for growing Basil successfully. Mulch heavily to conserve soil moisture.

Montrose County, CO (Zone 6a) Very short season
91 days
Last Spring Frost June 13
91 growing days
First Fall Frost September 12

Montrose County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.9

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 25 Transplant: Jun 27 🍅 Harvest: Aug 22 – Oct 24
Safe Start (90%) ✗ May not fit
Start indoors: May 8 Transplant: Jul 10 🍅 Harvest: Sep 4 – Nov 6

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 147 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Basil needs ~953 GDD — county provides 1,387 GDD Excellent fit

Basil Planting Timeline โ€” Montrose County, CO

Basil Planting Calendar

Activity When Date Range
Start Indoors April 25 Apr 25 โ€“ May 9
Transplant Outdoors June 27 Jun 27 โ€“ Jul 11
Direct Sow June 20 Jun 20 โ€“ Jul 11
Harvest August 22 Aug 22 โ€“ Oct 24

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

50โ€“75 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6a

Growing Season

91 days

Growing Tips for Montrose County

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

Level Up Your Garden

๐ŸŒพ 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 35ยฐF, under 45% humidity.

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

Frequently Asked Questions

When should I plant Basil in Montrose County, CO?

Montrose County is in Zone 6a with an average last frost of June 13. Plan your Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Montrose County, CO?

Montrose County, Colorado is in USDA Hardiness Zone 6a. The average last spring frost is June 13 and first fall frost is September 12.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Montrose County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Montrose County, CO. Local conditions may vary. Last updated: April 2026.