Blog

When to Plant Radish in Blaine County, ID

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.

Blaine County, Idaho is in USDA Zone 5a. The average last spring frost is May 18 and the first fall frost is October 3, giving you a growing season of approximately 138 days.

At an elevation of 7,128 feet, Blaine County receives approximately 17.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Radish to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Radish successfully. Mulch heavily to conserve soil moisture.

Blaine County, ID (Zone 5a) Short season
138 days
Last Spring Frost May 18
138 growing days
First Fall Frost October 3

Blaine County Soil Profile

Soil Type

Loam

Soil pH

6.7-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (92 days to spare)
Transplant: May 6 🍅 Harvest: Jun 3 – Jun 24
Recommended (50%) ✓ Fits season (89 days to spare)
Transplant: May 18 🍅 Harvest: Jun 15 – Jul 6
Safe Start (90%) ✓ Fits season (82 days to spare)
Transplant: Jun 11 🍅 Harvest: Jul 9 – Jul 30

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

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,122 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Radish needs ~370 GDD — county provides 1,794 GDD Excellent fit

Radish Planting Timeline โ€” Blaine County, ID

Radish Planting Calendar

Activity When Date Range
Direct Sow May 4 May 4 โ€“ May 25
Fall Sowing July 25 Jul 25 โ€“ Aug 8
Harvest June 1 Jun 1 โ€“ Jun 22

Plant 0.5" deep ยท 2" apart ยท Rows 6" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Direct Sow
June Harvest
July Fall Sowing
August Fall Sowing
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

22โ€“35 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

138 days

Growing Tips for Blaine 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

  • Hyssop

Level Up Your Garden

Frequently Asked Questions

When should I plant Radish in Blaine County, ID?

Blaine County is in Zone 5a with an average last frost of May 18. Plan your Radish planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Blaine County, ID?

Blaine County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 18 and first fall frost is October 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Blaine County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Blaine County, ID. Local conditions may vary. Last updated: April 2026.