When to plant Mint in Mercer County, IL
In Mercer County, Mint is a single-season spring crop — there's no second fall window. Plant April 24–May 8 for an 60–90-day harvest, finishing well before the October 15 first frost.
When to Plant Mint in Mercer County, IL
Mint is a vigorous perennial herb with refreshing, aromatic leaves used in teas, cocktails, and cooking. It spreads aggressively by underground runners.
Mercer County, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 15, giving you a growing season of approximately 181 days.
At an elevation of 777 feet, Mercer County receives approximately 37.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Mint to ensure they mature before fall.
Mercer County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.7
Drainage
Well Drained
Monthly Watering Guide for Mint
Mint needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Mint Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| May | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jun | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Aug | 4.3" | 4" | 0.3" | 💧 Light watering |
| Sep | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Oct | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Mercer County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Mint Planting Timeline — Mercer County, IL
Mint Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 24 | Apr 24 – May 8 |
| Harvest | June 26 | Jun 26 – Sep 4 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
High — keep soil consistently moist
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 5b
📆 Growing Season
181 days in Mercer County
Growing Tips for Mercer County
Always grow mint in containers or with underground barriers to control spreading. Harvest regularly to keep plants compact. Cut plants back in late summer for a fresh fall flush.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Mint in Other Locations
Frequently Asked Questions
When should I plant Mint in Mercer County, IL?
Mercer County is in Zone 5b with an average last frost of April 17. Plan your Mint planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mercer County, IL?
Mercer County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 15.
When should I plant Mint in Mercer County, IL?
In Mercer County, IL, plant Mint after the last frost (around April 17) and before the first frost (around October 15). Best results when soil holds above 50°F.
What growing zone is Mercer County, IL for Mint?
Mercer County sits in USDA Zone 5b. Mint grows reliably in zones 3a through 10b, so it's a good fit here.
Can Mint grow in Mercer County's climate?
Yes — Mint grows well in Mercer County's temperate climate. Mercer County averages a 181-day frost-free season, with last frost around April 17 and first frost around October 15.
Your Mercer County Garden Planner — Free
A 22-page printable planner built for Mercer 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.