Quick answer: 10 native Washington plants have a recorded bloom range that includes March.
10 species
- Bearberry Arctostaphylos uva-ursi · 16 states
- California bay laurel Umbellularia californica · 3 states
- Canada wild rye Elymus canadensis · 18 states
- Checker lily Fritillaria affinis · 3 states
- Douglas iris Iris douglasiana · 3 states
- Pacific madrone Arbutus menziesii · 3 states
- Pacific trillium Trillium ovatum · 3 states
- Quaking aspen Populus tremuloides · 24 states
- Tall Oregon grape Mahonia aquifolium · 3 states
- Winterfat Krascheninnikovia lanata · 6 states