Water regularly, do not over water.
Tolerates alkaline soil. In cooler climates, during the winter, provide mulch in order to prevent heaving. Divide in spring and take cuttings from spring to fall.1
Plant in a location that enjoys full sun and remember to water moderately. Keep in mind when planting that Purple rain is thought of as hardy, so this plant will survive close to or on freezing temperatures.It is said that these will not grow true from seed, and should be divided instead.
By our calculations, you should look at sowing Purple rain about 84 days before your last frost date.
Whorled clary, Lilac sage
1 finegardening.com/lilac-sage-salvia-verticillata-purple-rain