When to plant Radish in Mercer County, IL
Plant Radish in Mercer County after April 17; the prime window is April 3–April 24. A second sowing from August 6 to August 20 extends the harvest into fall.
When to Plant Radish in Mercer County, IL
Radishes are one of the fastest-growing vegetables, with some varieties ready in under a month. They come in round, elongated, and large winter types.
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 Radish to ensure they mature before fall.
Mercer County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Radish Planting Timeline — Mercer County, IL
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 3 | Apr 3 – Apr 24 |
| Harvest | May 1 | May 1 – May 22 |
| Fall Sowing | August 6 | Aug 6 – Aug 20 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Harvest |
| June | — |
| July | — |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
22–35 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
Direct sow every 1-2 weeks for continuous harvest. Do not transplant. Harvest spring radishes promptly to prevent them from becoming pithy and hot.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Radish in Other Locations
Frequently Asked Questions
When should I plant Radish in Mercer County, IL?
Mercer County is in Zone 5b with an average last frost of April 17. Plan your Radish 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 Radish in Mercer County, IL?
In Mercer County, IL, plant Radish 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 Radish?
Mercer County sits in USDA Zone 5b. Radish grows reliably in zones 2a through 11b, so it's a good fit here.
Can Radish grow in Mercer County's climate?
Yes — Radish 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.