When to plant Radish in Ada County, ID
Ada County gardeners should plant Radish between April 9 and April 30 in spring. With Ada County's Zone 7a climate (last frost April 23), Radish needs 22–35 days to mature — plant by September 11 for a full harvest. A second sowing from August 7 to August 21 extends the harvest into fall.
When to Plant Radish in Ada County, ID
July in Ada County, Idaho — your action list
Welcome to July in Zone 7a. These are the moves that will have the biggest impact on your growing season.
Coming up in August — start thinking about
- Fall sowing: radish
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.
Ada County, Idaho is in USDA Zone 7a. The average last spring frost is April 23 and the first fall frost is October 16, giving you a growing season of approximately 176 days.
At an elevation of 4,372 feet, Ada County receives approximately 19.8 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Radish during the growing season. With low rainfall, drip irrigation is essential for growing Radish successfully. Mulch heavily to conserve soil moisture.
Ada County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.7
Drainage
Well Drained
Radish 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 Ada County
How your county's soil matches Radish's growing requirements.
Soil pH
Your soil pH (6.4–7.7) is more alkaline than Radish prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Ada County is excellent for Radish — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Radish.
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.
Radish Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
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 | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | 2.2" | 2" | 0.2" | 💧 Light watering |
| May | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Jul | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Aug | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Oct | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Ada 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 — Ada County, ID
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 9 | Apr 9 – Apr 30 |
| Harvest | May 7 | May 7 – May 28 |
| 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 |
| May | Harvest |
| June | — |
| July | — |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Only during dry spells
📅 Days to Maturity
22–35 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 7a
📆 Growing Season
176 days in Ada County
Growing Tips for Radish in Ada County
Direct sow Radish outdoors after April 23 in Ada County when soil has warmed and frost danger has passed.
Your generous 176.0-day season in Ada 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 Ada County, ID?
Ada County is in Zone 7a with an average last frost of April 23. Plan your Radish planting based on this frost date — see the calendar above for exact timing.
What planting zone is Ada County, ID?
Ada County, Idaho is in USDA Hardiness Zone 7a. The average last spring frost is April 23 and first fall frost is October 16.
When should I plant Radish in Ada County, ID?
In Ada County, ID, plant Radish after the last frost (around April 23) and before the first frost (around October 16). Best results when soil holds above 50°F.
What growing zone is Ada County, ID for Radish?
Ada County sits in USDA Zone 7a. Radish grows reliably in zones 2a through 11b, so it's a good fit here.
Can Radish grow in Ada County's climate?
Yes — Radish grows well in Ada County's temperate climate. Ada County averages a 176-day frost-free season, with last frost around April 23 and first frost around October 16.
Your Ada County Garden Planner — Free
A 22-page printable planner built for Ada 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.