When to plant Mint in Simpson,
Plant Mint in Simpson, between April 14 and April 28 — the only viable window. Zone 7a's short season (197 frost-free days) rules out a fall crop.
When to Plant Mint in Simpson, IL
Your June game plan for Simpson, IL
Your Simpson, IL garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.
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Basket week: mint
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
Looking ahead to July
- First harvests: mint
Mint is a vigorous perennial herb with refreshing, aromatic leaves used in teas, cocktails, and cooking. It spreads aggressively by underground runners.
Simpson, Illinois is in USDA Zone 7a. The average last spring frost is April 7 and the first fall frost is October 21, giving you a growing season of approximately 197 days.
At an elevation of 1,006 feet, Johnson County receives approximately 39.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Mint during the growing season.
Simpson Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7.2
Drainage
Well Drained
Mint 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.
Soil Compatibility in Simpson
How your county's soil matches Mint's growing requirements.
Soil pH
Your soil pH (5.9–7.2) overlaps with Mint's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Johnson County is excellent for Mint — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.8%) — Mint will thrive.
How to Plant Mint
Succession Planting Mint
Sow every 6.9 weeks. Last sowing by Jul 23 to harvest before frost.
Mint Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Mint
Mint needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Mint Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 3" | 3.6" | 0" | ✅ Rainfall sufficient |
| May | 3" | 4.2" | 0" | ✅ Rainfall sufficient |
| Jun | 3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jul | 3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Aug | 3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Sep | 3" | 3.3" | 0" | ✅ Rainfall sufficient |
| Oct | 3" | 3.2" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.9" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Johnson County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Mint Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Mint Planting Timeline — Simpson, IL
Mint Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 14 | Apr 14 – Apr 28 |
| Harvest | June 16 | Jun 16 – Aug 25 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.7"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
197 days in Johnson County
Growing Tips for Mint in Simpson
Direct sow Mint outdoors after April 07 in Johnson County when soil has warmed and frost danger has passed.
General growing tips
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
When should I plant Mint in Simpson, ?
In Simpson, , plant Mint after the last frost (around April 7) and before the first frost (around October 21). Best results when soil holds above 50°F.
What growing zone is Simpson, for Mint?
Simpson sits in USDA Zone 7a. Mint grows reliably in zones 3a through 10b, so it's a good fit here.
Can Mint grow in Simpson's climate?
Yes — Mint grows well in Simpson's temperate climate. Simpson averages a 197-day frost-free season, with last frost around April 7 and first frost around October 21.
Your Johnson County Garden Planner — Free
A 22-page printable planner built for Johnson County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.