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When to plant Basil in Simla, CO

Simla's 144-day season only supports one Basil planting per year. Sow between May 19 and June 9 for the best chance at full maturity before October 3.

When to Plant Basil in Simla, CO

Basil
Elbert County, Colorado Zone 5b June

Your June gardening checklist

Your Elbert County, Colorado garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.

Avg. last frost May 12
Avg. first frost October 3
Soil temp (4") 54°F
Watering High
Pest pressure High
Daylight 14.7 hrs
  1. Start basil indoors

    Your window is short. These crops want several weeks of indoor growth before they go outside.

July prep starts now
  • First harvests: 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.

Simla, Colorado is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is October 3, giving you a growing season of approximately 144 days.

At an elevation of 5,587 feet, Elbert County receives approximately 22.1 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Basil during the growing season.

Simla, CO (Zone 5b) Short season
144 days
Last Spring Frost May 12
144 growing days
First Fall Frost October 3

Simla Soil Profile

Soil Type

Loam

Soil pH

6.2-7.7

Drainage

Well Drained

Basil Planting Risk Windows

Early Start (70% safe) ✓ Fits season (10 days to spare)
Start indoors: Mar 15 Transplant: May 17 🍅 Harvest: Jul 12 – Sep 13
Recommended (50%) ✓ Fits season (11 days to spare)
Start indoors: Mar 24 Transplant: May 26 🍅 Harvest: Jul 21 – Sep 22
Safe Start (90%) ✓ Fits season (8 days to spare)
Start indoors: Apr 9 Transplant: Jun 11 🍅 Harvest: Aug 6 – Oct 8

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 Simla

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

Soil pH

Your soil pH (6.2–7.7) overlaps with Basil's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Elbert 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 (2.8%). Annual compost additions will help Basil.

How to Plant Basil

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

Succession Planting Basil

3
successive plantings in your 144-day season

Sow every 5.7 weeks. Last sowing by Jul 20 to harvest before frost.

Basil Water Budget

Plant needs
0.6″/week
Rainfall provides
0.6″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 208 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 1.8" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 2.6" 2.4" 0.2" 💧 Light watering
Jun 2.6" 1.7" 0.9" 💧 Light watering
Jul 2.6" 1.9" 0.7" 💧 Light watering
Aug 2.6" 2.3" 0.3" 💧 Light watering
Sep 2.6" 2" 0.6" 💧 Light watering
Oct 2.6" 1.9" 0.7" 💧 Light watering
Nov 1.8" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Elbert 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 ~953 GDD — county provides 2,196 GDD Excellent fit

Basil Planting Timeline — Simla, CO

Basil Planting Calendar

Activity When Date Range
Start Indoors March 24 Mar 24 – Apr 7
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 19 May 19 – Jun 9
Harvest July 21 Jul 21 – Sep 22

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · Only during dry spells

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

144 days in Elbert County

Growing Tips for Basil in Simla

Direct sow Basil outdoors after May 12 in Elbert 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.

When should I plant Basil in Simla, CO?

In Simla, CO, plant Basil after the last frost (around May 12) and before the first frost (around October 3). Best results when soil holds above 50°F.

What growing zone is Simla, CO for Basil?

Simla sits in USDA Zone 5b. Basil grows reliably in zones 4a through 11b, so it's a good fit here.

Can Basil grow in Simla's climate?

Yes — Basil grows well in Simla's temperate climate. Simla averages a 144-day frost-free season, with last frost around May 12 and first frost around October 3.

🌱

Your Elbert County Garden Planner — Free

A 22-page printable planner built for Elbert County (Zone 5b). 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 Elbert County, CO. Local conditions may vary. Last updated: June 2026.