Set plants 8 to 12 inches apart in filtered shade in a rich, highly organic soil. Primroses thrive best in a cool environment and sheltered against wind. They do poorly where summers are hot.
Keep soil moist, watering during periods of drought. A mulch will help conserve moisture during the growing season and will discourage heaving during winter. Divide in early fall every 3 to 4 years to rejuvenate, when necessary. P. sieboldii usually goes dormant in the summer, so be sure not to disturb them while they are dormant.