# Milkweed in Colorado

> 19 milkweed species are recorded in Colorado.

Source: https://milkweedusa.com/states/colorado/  
Licence: CC BY 4.0 (Milkweed USA)

## Overview

Colorado is one of the most milkweed-diverse states in the West, with roughly twenty species spanning shortgrass plains, foothills, mesas and the Western Slope. Showy milkweed along the South Platte and Arkansas river corridors does most of the monarch work, while the eastern plains hold rarities such as wheel milkweed found almost nowhere else.

- Species recorded: 19
- USDA hardiness zones: 3a–7a
- Monarch flyway: both
- Best time to sow seed outdoors: September to November, before the ground freezes

## Species recorded in Colorado

| Common name | Scientific name | Native | Height | Bloom |
| --- | --- | --- | --- | --- |
| Swamp Milkweed | Asclepias incarnata | Yes | 3 ft–5 ft | June to September |
| Butterfly Weed | Asclepias tuberosa | Yes | 1 ft–3 ft | May to September |
| Showy Milkweed | Asclepias speciosa | Yes | 2 ft–5 ft | May to August |
| Antelope Horns | Asclepias asperula | Yes | 1 ft–2 ft | March to July |
| Green Antelopehorn | Asclepias viridis | Yes | 1 ft–2.5 ft | April to July |
| Common Milkweed | Asclepias syriaca | Yes | 3 ft–6 ft | June to August |
| Whorled Milkweed | Asclepias verticillata | Yes | 1 ft–2.5 ft | June to September |
| Hall’s Milkweed | Asclepias hallii | Yes | 1.5 ft–3 ft | June to August |
| Green Comet Milkweed | Asclepias viridiflora | Yes | 1 ft–3 ft | May to August |
| Broadleaf Milkweed | Asclepias latifolia | Yes | 1 ft–3 ft | May to August |
| Sand Milkweed | Asclepias arenaria | Yes | 1 ft–2.5 ft | June to August |
| Plains Milkweed | Asclepias pumila | Yes | 4 in–1 ft | June to September |
| Engelmann’s Milkweed | Asclepias engelmanniana | Yes | 2 ft–5 ft | June to August |
| Slimleaf Milkweed | Asclepias stenophylla | Yes | 1.5 ft–3.3 ft | June to August |
| Poison Milkweed | Asclepias subverticillata | Yes | 1 ft–3 ft | June to September |
| Pallid Milkweed | Asclepias cryptoceras | Yes | 4 in–1 ft | April to June |
| Dwarf Milkweed | Asclepias involucrata | Yes | 4 in–10 in | April to June |
| Longhood Milkweed | Asclepias macrotis | Yes | 8 in–1.7 ft | April to August |
| Wheel Milkweed | Asclepias uncialis | Yes | 2 in–6 in | April to June |

## How to cite

Milkweed USA. (2026). Milkweed in Colorado. https://milkweedusa.com/states/colorado/