When to Plant Radish in Carter County, MT
Your May planting checklist for Carter County, Montana
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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Outdoor sowing time: radish
Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.
Coming up in June — start thinking about
- First harvests: radish
- 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.
Carter County, Montana is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 22, giving you a growing season of approximately 130 days.
At an elevation of 7,923 feet, Carter County receives approximately 19.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, 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.
Carter County Soil Profile
Soil Type
Loam
Soil pH
6.4-8.2
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 Carter County
How your county's soil matches Radish's growing requirements.
Soil pH
Your soil pH (6.4–8.2) is more alkaline than Radish prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Carter County is excellent for Radish — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.7%). Annual compost additions will help Radish.
How to Plant Radish
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Radish
Sow every 2.4 weeks. Last sowing by Aug 18 to harvest before frost.
For a dedicated fall crop, sow by Jun 30.
Plant 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 | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 2.2" | 0" | ❄️ Dormant |
| May | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Jul | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Aug | 2.2" | 1.9" | 0.3" | 💧 Light watering |
| Sep | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Oct | — | 1.7" | 0" | ❄️ Dormant |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Carter 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 — Carter County, MT
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 8 | May 8 – May 29 |
| Harvest | June 5 | Jun 5 – Jun 26 |
| Fall Sowing | June 30 | Jun 30 – Jul 14 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | Fall Sowing Harvest |
| July | Fall Sowing |
| August | — |
| 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: too_alkaline
🗺️ USDA Zone
Zone 4b
📆 Growing Season
130 days in Carter County
Growing Tips for Radish in Carter County
Direct sow Radish outdoors after May 15 in Carter County when soil has warmed and frost danger has passed.
Your generous 130.0-day season in Carter 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 Carter County, MT?
Carter County is in Zone 4b with an average last frost of May 15. Plan your Radish planting based on this frost date — see the calendar above for exact timing.
What planting zone is Carter County, MT?
Carter County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 22.
Your Carter County Garden Planner — Free
A 24-page printable planner built for Carter County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.