Black Magic is a popular variety of Cornflower, which belongs to the Centaurea genus (Centaurea cyanus 'Black Magic'). This variety is an Flower that typically grows as an Annual, which is defined as a plant that matures and completes its lifecycle over the course of a single year. Black Magic normally grows to a mature height of 90.0 cm (that's 2.93 feet imperial).
As Black Magic Cornflower is a low maintanence plant, it is great for beginner gardeners and those that like gardens that don't need much overseeing.
This variety plant info is provided by the myfolia gardener's wiki. All details about Black Magic have been kindly provided by our members.
By our calculations, you should look at sowing Black Magic about 7 days after your last frost date.