When to Plant Hostas in Colorado
The king of shade gardens. Hostas come in hundreds of varieties and get more beautiful with each passing year.
The Short Answer
Colorado Frost Dates
Your planting dates depend on which part of Colorado you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Front Range (Denver) | 5a, 5b, 6a | May 1 - May 15 | Sep 25 - Oct 10 |
| Western Slope | 4b, 5a, 5b, 6a | May 10 - Jun 1 | Sep 15 - Oct 5 |
| Mountain Regions | 3a, 3b, 4a, 4b | Jun 1 - Jun 20 | Aug 25 - Sep 15 |
Hostas Planting Schedule for Colorado
Front Range (Denver) (Zones 5a, 5b, 6a)
Average last frost: May 1 - May 15 · Average first frost: Sep 25 - Oct 10
Western Slope (Zones 4b, 5a, 5b, 6a)
Average last frost: May 10 - Jun 1 · Average first frost: Sep 15 - Oct 5
Mountain Regions (Zones 3a, 3b, 4a, 4b)
Average last frost: Jun 1 - Jun 20 · Average first frost: Aug 25 - Sep 15
Growing Hostas in Colorado
Hostas in Colorado's Climate
Your climate is hosta heaven. Cold winters provide necessary dormancy, moderate summers prevent heat scorch, and abundant shade from deciduous forests creates ideal growing conditions. Michigan, Minnesota, and Wisconsin grow some of the finest hostas in the country. The only pest concern is slugs — iron phosphate bait handles them.
Soil Considerations for Colorado
Alkaline clay soils common along Front Range. Rocky, thin soils in mountains. Amend heavily with compost and sulfur to lower pH.
Colorado Climate & Growing Season
High altitude means intense sun but cool nights. Low humidity. Hail risk in late spring. Short but intense growing season at elevation. Hostas can handle frost well, which is an advantage in Colorado's climate. You can push planting dates earlier in spring and extend into fall.
Growing season length varies across Colorado: Front Range (Denver) (5a, 5b, 6a) has a last frost around May 1 - May 15, while Mountain Regions (3a, 3b, 4a, 4b) sees frost end around Jun 1 - Jun 20. This difference matters for hostas — adjust your planting dates to match your specific region.
Growing Tips
Plant divisions or nursery plants in spring or fall. Slugs are the main enemy — use iron phosphate bait. Mulch to retain moisture.
Companion Planting
Plant hostas alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026