When to Plant Basil in Iroquois County, IL
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.
Iroquois County, Illinois is in USDA Zone 5a. The average last spring frost is April 18 and the first fall frost is October 13, giving you a growing season of approximately 178 days.
At an elevation of 1,345 feet, Iroquois County receives approximately 30 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Basil during the growing season.
Iroquois County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-6.7
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
Basil Planting Timeline — Iroquois County, IL
Basil Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 28 | Feb 28 – Mar 14 |
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Direct Sow | April 25 | Apr 25 – May 16 |
| Harvest | June 27 | Jun 27 – Aug 29 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| 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
178 days
Growing Tips for Iroquois 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
Level Up Your Garden
Isolate 150 ft between varieties. Different basil species can cross.
Basil in Other Locations
Frequently Asked Questions
When should I plant Basil in Iroquois County, IL?
Iroquois County is in Zone 5a with an average last frost of April 18. Plan your Basil planting based on this frost date — see the calendar above for exact timing.
What planting zone is Iroquois County, IL?
Iroquois County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 18 and first fall frost is October 13.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Iroquois County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
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