When to Plant Thai Basil in Lee County, IL
Thai basil has a distinctive anise-licorice flavor with sturdy purple stems and small leaves. It is essential in Thai, Vietnamese, and other Southeast Asian cuisines.
Lee County, Illinois is in USDA Zone 5a. The average last spring frost is April 22 and the first fall frost is October 14, giving you a growing season of approximately 175 days.
At an elevation of 1,010 feet, Lee County receives approximately 33.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Thai Basil to ensure they mature before fall.
Lee County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.9
Drainage
Well Drained
Plant Planting Risk Windows
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
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Thai Basil Planting Timeline — Lee County, IL
Thai Basil Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 4 | Mar 4 – Mar 18 |
| Transplant Outdoors | May 6 | May 6 – May 20 |
| Direct Sow | April 29 | Apr 29 – May 20 |
| Harvest | July 1 | Jul 1 – Sep 2 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
50–75 days
Soil pH
6 – 7
USDA Zone
Zone 5a
Growing Season
175 days
Growing Tips for Lee County
Start seeds indoors or direct sow after last frost. Thai basil holds up better to heat in cooking than sweet basil. Pinch flowers to prolong leaf production.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Thai Basil in Other Locations
Frequently Asked Questions
When should I plant Thai Basil in Lee County, IL?
Lee County is in Zone 5a with an average last frost of April 22. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lee County, IL?
Lee County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 22 and first fall frost is October 14.
Plan Your Garden with Confidence
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