Keep in mind when planting that Purple Rain is thought of as half hardy, so protect with a row cover whenever the temperatures drop.
Try to aim for a seed spacing of at least
8.97 inches (23.0 cm) and sow at a depth of around
0.0 inches (0.0 cm). Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Purple Rain about 90 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Purple Rain is a half hardy plant.