Try to plant in a location that enjoys partial sun and remember to water moderately. Keep in mind when planting that Rotstern is thought of as hardy, so it can be safe to leave outdoors for the majority of winter (although if in doubt, using a row cover is often a good idea).
Growing Rotstern from seed
By our calculations, you should look at sowing Rotstern about 30 days before your last frost date.
Transplanting Rotstern
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Rotstern is a hardy plant.