Black Ball is a popular variety of Cornflower, which belongs to the Centaurea genus (Centaurea cyanus 'Black Ball'). A type of Flower, it mainly grows as an Annual plant - which means it typically only grows best for a single growing season. Black Ball normally grows to a mature height of 90.0 cm (that's 2.93 feet imperial).
As Black Ball 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 Ball have been kindly provided by our members.
By our calculations, you should look at sowing Black Ball about 7 days after your last frost date.