Famous purple coneflower, better known today by its Latin name "Echinacea", is easily grown as a classic perennial. Plant the seed spring, summer or fall, but be patient. The roots of this speices are thick and fleshy. This means it develops quickly in loose soil, much more slowly in heavy clay. The plant does equally well in both, but if your soil is heavy, be prepared to wait at least two years for good bloom.