# Milkweed in Oregon

> 4 milkweed species are recorded in Oregon.

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

## Overview

Showy milkweed dominates the Willamette Valley and the state’s eastern high desert, while narrowleaf milkweed occupies southern Oregon’s drier valleys and heartleaf milkweed climbs into the Siskiyou foothills. Oregon is a critical spring corridor for western monarchs leaving the California coast.

- Species recorded: 4
- USDA hardiness zones: 4a–9b
- Monarch flyway: western
- Best time to sow seed outdoors: October to December, so the seed uses winter rain

## Species recorded in Oregon

| Common name | Scientific name | Native | Height | Bloom |
| --- | --- | --- | --- | --- |
| Showy Milkweed | Asclepias speciosa | Yes | 2 ft–5 ft | May to August |
| Narrowleaf Milkweed | Asclepias fascicularis | Yes | 2 ft–4 ft | May to September |
| Heartleaf Milkweed | Asclepias cordifolia | Yes | 1 ft–3 ft | May to July |
| Pallid Milkweed | Asclepias cryptoceras | Yes | 4 in–1 ft | April to June |

## How to cite

Milkweed USA. (2026). Milkweed in Oregon. https://milkweedusa.com/states/oregon/