Keep in mind when planting that Autumn Leaves is thought of as very hardy, so this plant will typically do well in a variety of different extremes of cold temperature.
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 Autumn Leaves about 63 days before your last frost date.
As Autumn Leaves is very hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.