|Purple Umbrella has deep purple flowers. In general, Trachelium caeruleum is a clumping perennial. Leaves are narrow, toothed, and dark green, held covering the stems. Flowers are bluish-purple in broad, domed clusters. It is an undemanding, easy to grow plant, with good cut flowers. Blooming season is over the summer. In colder climates it can be sown indoors, and transplanted out as a summer annual.