Keep in mind when planting that Purple Mountain Majesty is thought of as very hardy, so this plant will tend to survive through freezing conditions.
Try to ensure a gap of at least
4.68 inches (12.0 cm) when sowing to prevent overcrowding your seedlings.
By our calculations, you should look at sowing Purple Mountain Majesty about 63 days before your last frost date.
As Purple Mountain Majesty is very hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.