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When to Plant Basil in Washington County, OK

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.

Washington County, Oklahoma is in USDA Zone 7a. The average last spring frost is April 7 and the first fall frost is October 25, giving you a growing season of approximately 201 days.

At an elevation of 459 feet, Washington County receives approximately 25 inches of rainfall annually with predominantly loam soil. Summer highs average 92ยฐF, providing good warmth for Basil during the growing season.

Washington County, OK (Zone 7a) Long season
201 days
Last Spring Frost April 7
201 growing days
First Fall Frost October 25

Washington County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (72 days to spare)
Start indoors: Feb 8 Transplant: Apr 12 🍅 Harvest: Jun 7 – Aug 9
Recommended (50%) ✓ Fits season (68 days to spare)
Start indoors: Feb 17 Transplant: Apr 21 🍅 Harvest: Jun 16 – Aug 18
Safe Start (90%) ✓ Fits season (72 days to spare)
Start indoors: Mar 3 Transplant: May 5 🍅 Harvest: Jun 30 – Sep 1

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
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,025 gal / 100 sq ft
Drought risk

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

Basil needs ~1,188 GDD — county provides 3,819 GDD Excellent fit

Basil Planting Timeline โ€” Washington County, OK

Basil Planting Calendar

Activity When Date Range
Start Indoors February 17 Feb 17 โ€“ Mar 3
Transplant Outdoors April 21 Apr 21 โ€“ May 5
Direct Sow April 14 Apr 14 โ€“ May 5
Harvest June 16 Jun 16 โ€“ Aug 18

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

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Harvest
September โ€”
October โ€”
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 7a

Growing Season

201 days

Growing Tips for Washington 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 Washington County, OK?

Washington County is in Zone 7a with an average last frost of April 7. Plan your Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Washington County, OK?

Washington County, Oklahoma is in USDA Hardiness Zone 7a. The average last spring frost is April 7 and first fall frost is October 25.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Washington County gardeners in Zone 7a 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 Washington County, OK. Local conditions may vary. Last updated: April 2026.