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When to Plant Radish in Phillips County, MT

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.

Phillips County, Montana is in USDA Zone 4a. The average last spring frost is May 18 and the first fall frost is September 21, giving you a growing season of approximately 126 days.

At an elevation of 6,886 feet, Phillips County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, 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.

Phillips County, MT (Zone 4a) Short season
126 days
Last Spring Frost May 18
126 growing days
First Fall Frost September 21

Phillips County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (75 days to spare)
Transplant: May 12 🍅 Harvest: Jun 9 – Jun 30
Recommended (50%) ✓ Fits season (77 days to spare)
Transplant: May 18 🍅 Harvest: Jun 15 – Jul 6
Safe Start (90%) ✓ Fits season (78 days to spare)
Transplant: May 31 🍅 Harvest: Jun 28 – Jul 19

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
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 493 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Radish needs ~285 GDD — county provides 1,260 GDD Excellent fit

Radish Planting Timeline โ€” Phillips County, MT

Radish Planting Calendar

Activity When Date Range
Direct Sow May 11 May 11 โ€“ Jun 1
Fall Sowing June 29 Jun 29 โ€“ Jul 13
Harvest June 8 Jun 8 โ€“ Jun 29

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 Direct Sow Fall Sowing Harvest
July Fall Sowing
August โ€”
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 4a

Growing Season

126 days

Growing Tips for Phillips 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 Phillips County, MT?

Phillips County is in Zone 4a 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 Phillips County, MT?

Phillips County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 18 and first fall frost is September 21.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Phillips County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

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