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When to Plant Basil in Dolores County, CO

Dolores County, Colorado Zone 6b May

What to do in May

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

Avg. last frost June 18
Avg. first frost September 8
Soil temp (4") 38°F
Watering Moderate
Pest pressure Low
Daylight 14 hrs
June prep starts now
  • 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.

Dolores County, Colorado is in USDA Zone 6b. The average last spring frost is June 18 and the first fall frost is September 8, giving you a growing season of approximately 82 days.

At an elevation of 7,506 feet, Dolores County receives approximately 23.1 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Basil during the growing season.

Dolores County, CO (Zone 6b) Very short season
82 days
Last Spring Frost June 18
82 growing days
First Fall Frost September 8

Dolores County Soil Profile

Soil Type

Loam

Soil pH

6.3-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 19 Transplant: Jun 21 🍅 Harvest: Aug 16 – Oct 18
Recommended (50%) ✗ May not fit
Start indoors: Apr 30 Transplant: Jul 2 🍅 Harvest: Aug 27 – Oct 29
Safe Start (90%) ✗ May not fit
Start indoors: May 11 Transplant: Jul 13 🍅 Harvest: Sep 7 – Nov 9

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 Dolores County

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

Soil pH

Your soil pH (6.3–8.3) is more alkaline than Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Basil.

How to Plant Basil

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

Plant Water Budget

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

Water stress score is 8/10 — 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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 2.6" 1.8" 0.8" 💧 Light watering
Jul 2.6" 1.9" 0.7" 💧 Light watering
Aug 2.6" 2.1" 0.5" 💧 Light watering
Sep 2.6" 2.1" 0.5" 💧 Light watering
Oct 2.2" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Dolores 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 ~859 GDD — county provides 1,127 GDD Excellent fit

Basil Planting Timeline — Dolores County, CO

Basil Planting Calendar

Activity When Date Range
Start Indoors April 30 Apr 30 – May 14
Transplant Outdoors July 2 Jul 2 – Jul 16
Direct Sow June 25 Jun 25 – Jul 16
Harvest August 27 Aug 27 – Oct 29

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

Month-by-Month Timeline

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

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 6b

📆 Growing Season

82 days in Dolores County

Growing Tips for Basil in Dolores County

Direct sow Basil outdoors after June 18 in Dolores 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 Dolores County, CO?

Dolores County is in Zone 6b with an average last frost of June 18. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dolores County, CO?

Dolores County, Colorado is in USDA Hardiness Zone 6b. The average last spring frost is June 18 and first fall frost is September 8.

🌱

Your Dolores County Garden Planner — Free

A 24-page printable planner built for Dolores County (Zone 6b). 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 Dolores County, CO. 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.