You can plant them at any time of year from spring
to fall(I have~if they are plants).
Plant with the crown at soil level, not below.
Cover them with hay, leaves or straw.
I live in a cold climate and never had a problem with them, they like alot of compost in the soil as well.
I mow them over with the lawn mower in the late fall before it snows.
Mind you they won't over winter here in pots. too cold.