Arnica montana in Zones 5 to 9

We live in the Puget Sound area of Washington state, USA.
We would like to establish Arnica montana on our property. Will it grow in our area? Any special suggestions for establishing Arnica?

Since Arnica montana is hardy in zones 6 to 9 it can be grown in all but the interior northern portions of Washington state, since those portions are in zone 5.
Arnica montana likes a slightly acid soil. If your soil is alkaline, I would suggest that you construct a raised bed with acid peat moss as the major ingredient of the soil. Raising the soil level prevents run-off from turning the soil alkaline in short order. Make sure the drainage is good by including sand in the mix.