When to Plant Nasturtiums in Idaho
Edible flowers that double as pest traps. Plant near vegetables to lure aphids away from your food crops.
The Short Answer
Idaho Frost Dates
Your planting dates depend on which part of Idaho you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern Idaho | 5a, 5b, 6a | May 5 - May 25 | Sep 15 - Oct 5 |
| Boise Area | 6b, 7a | Apr 20 - May 5 | Oct 5 - Oct 20 |
| Eastern Idaho | 3b, 4a, 4b, 5a | May 20 - Jun 10 | Sep 1 - Sep 20 |
Nasturtiums Planting Schedule for Idaho
Northern Idaho (Zones 5a, 5b, 6a)
Average last frost: May 5 - May 25 · Average first frost: Sep 15 - Oct 5
Boise Area (Zones 6b, 7a)
Average last frost: Apr 20 - May 5 · Average first frost: Oct 5 - Oct 20
Eastern Idaho (Zones 3b, 4a, 4b, 5a)
Average last frost: May 20 - Jun 10 · Average first frost: Sep 1 - Sep 20
Growing Nasturtiums in Idaho
Nasturtiums in Idaho's Climate
Nasturtiums add edible beauty to cold-climate gardens from June through frost. Direct sow after last frost — they grow fast in summer warmth. Plant near vegetables as companion and trap plants for aphids. The flowers and leaves have a peppery, watercress-like flavor that brightens salads.
Soil Considerations for Idaho
Volcanic ash soils in south — excellent for gardening. Rocky soils in mountains. Alkaline in many areas. Make sure soil has warmed to at least 55°F before planting nasturtiums outside.
Idaho Climate & Growing Season
Arid climate. Low humidity. Hot days and cool nights. Irrigation essential. Short season at higher elevations. Nasturtiums cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.
Growing season length varies across Idaho: Northern Idaho (5a, 5b, 6a) has a last frost around May 5 - May 25, while Eastern Idaho (3b, 4a, 4b, 5a) sees frost end around May 20 - Jun 10. This difference matters for nasturtiums — transplant timing shifts by several weeks across the state.
Growing Tips
Both flowers and young leaves are edible with a peppery taste. Thrives in poor soil — too much nitrogen means all leaves, no flowers.
Companion Planting
Plant nasturtiums alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026