Arnica chamissonis, the Chamisso arnica, is a North American species of plants in the sunflower family. It is very similar to Arnica montana. Arnica chamissonis is native to North America and naturalized in parts of Europe while A. montana is indigenous to Europe.
Provide water to arnica when the top inch of the surrounding soil is dry. Don’t allow arnica to become too dry as its not drought resistant. Don’t soak the soil either though.
It’s a good gardening practice to fertilize your garden before you plant. Arnica is no different. The beauty of arnica is you don’t need to fertilize again. It’s adept at growing without extra feeding. Use a balanced fertilizer and dig in well before planting.