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When to Plant Basil in Johnson County, WY

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.

Johnson County, Wyoming is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 21, giving you a growing season of approximately 127 days.

At an elevation of 8,281 feet, Johnson County receives approximately 23.7 inches of rainfall annually with predominantly loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Basil to ensure they mature before fall.

Johnson County, WY (Zone 4a) Short season
127 days
Last Spring Frost May 17
127 growing days
First Fall Frost September 21

Johnson 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: Mar 18 Transplant: Jun 3 🍅 Harvest: Jul 29 – Sep 30
Recommended (50%) ✗ May not fit
Start indoors: Mar 22 Transplant: Jun 7 🍅 Harvest: Aug 2 – Oct 4
Safe Start (90%) ✗ May not fit
Start indoors: Apr 12 Transplant: Jun 28 🍅 Harvest: Aug 23 – Oct 25

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
0.8″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 700 gal / 100 sq ft
Drought risk

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

Basil needs ~672 GDD — county provides 1,365 GDD Excellent fit

Basil Planting Timeline โ€” Johnson County, WY

Basil Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 โ€“ Apr 5
Transplant Outdoors June 7 Jun 7 โ€“ Jun 21
Direct Sow May 24 May 24 โ€“ Jun 14
Harvest August 2 Aug 2 โ€“ Oct 4

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors
May Direct Sow
June Transplant Outdoors Direct Sow
July โ€”
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 4a

Growing Season

127 days

Growing Tips for Johnson 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 Johnson County, WY?

Johnson County is in Zone 4a with an average last frost of May 17. Plan your Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Johnson County, WY?

Johnson County, Wyoming is in USDA Hardiness Zone 4a. The average last spring frost is May 17 and first fall frost is September 21.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Johnson County gardeners in Zone 4a 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 Johnson County, WY. Local conditions may vary. Last updated: April 2026.