When to Plant Radish in Louisa County, IA
May to-do list for Louisa County, Iowa
Your garden in Louisa County, Iowa is working on a schedule, even when you're not. Here's where you should be this May.
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Basket week: radish
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
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.
Louisa County, Iowa is in USDA Zone 5b. The average last spring frost is April 16 and the first fall frost is October 16, giving you a growing season of approximately 183 days.
At an elevation of 1,022 feet, Louisa County receives approximately 38.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Radish during the growing season.
Louisa County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7.3
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.
Soil Compatibility in Louisa County
How your county's soil matches Radish's growing requirements.
Soil pH
Your soil pH (6.0–7.3) overlaps with Radish's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Louisa County is excellent for Radish — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.0%) — Radish will thrive.
How to Plant Radish
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Radish
Sow every 2.4 weeks. Last sowing by Sep 11 to harvest before frost.
For a dedicated fall crop, sow by Aug 07.
Plant Water Budget
Monthly Watering Guide for Radish
Radish needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Radish Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 5.2" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 2.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Louisa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Radish 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.
Radish Planting Timeline — Louisa County, IA
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 2 | Apr 2 – Apr 23 |
| Harvest | April 30 | Apr 30 – May 21 |
| Fall Sowing | August 7 | Aug 7 – Aug 21 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow Harvest |
| May | Harvest |
| June | — |
| July | — |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
22–35 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
183 days in Louisa County
Growing Tips for Radish in Louisa County
Direct sow Radish outdoors after April 16 in Louisa County when soil has warmed and frost danger has passed.
Your generous 183.0-day season in Louisa County allows multiple plantings of Radish. Sow every 11.0 days for continuous harvest.
Common pests for Radish in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
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 Louisa County, IA?
Louisa County is in Zone 5b with an average last frost of April 16. Plan your Radish planting based on this frost date — see the calendar above for exact timing.
What planting zone is Louisa County, IA?
Louisa County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 16 and first fall frost is October 16.
Your Louisa County Garden Planner — Free
A 24-page printable planner built for Louisa 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.