When to Plant Radish in Hamilton County, IA
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.
Hamilton County, Iowa is in USDA Zone 4b. The average last spring frost is May 1 and the first fall frost is October 7, giving you a growing season of approximately 159 days.
At an elevation of 1,210 feet, Hamilton County receives approximately 35.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Radish to ensure they mature before fall.
Hamilton County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.8
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
Radish Planting Timeline — Hamilton County, IA
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 24 | Apr 24 – May 15 |
| Fall Sowing | July 15 | Jul 15 – Jul 29 |
| Harvest | May 22 | May 22 – Jun 12 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow Harvest |
| June | Harvest |
| July | Fall Sowing |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
22–35 days
Soil pH
6 – 7
USDA Zone
Zone 4b
Growing Season
159 days
Growing Tips for Hamilton 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
Level Up Your Garden
Radish in Other Locations
Frequently Asked Questions
When should I plant Radish in Hamilton County, IA?
Hamilton County is in Zone 4b with an average last frost of May 1. Plan your Radish planting based on this frost date — see the calendar above for exact timing.
What planting zone is Hamilton County, IA?
Hamilton County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 1 and first fall frost is October 7.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Hamilton County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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