Although not directly toxic, canna has a unique reputation of lethality. Its spherical seeds are so hard that they were historically used as shot. Many victims are now pushing up daisies. Those who survived were pulling out cannas.
Old fashioned varieties that get up to six feet tall seem to be at least as popular as shorter modern varieties that get less than half as tall, probably because their bold foliage is as appealing as their colorful but awkwardly structured flowers. The big leaves can be cool green, rich reddish bronze or variegated. Red, orange, yellow, pink or rarely white flowers that bloom from summer to autumn are striking amongst the lush foliage, but are too perishable to be good cut flowers.
Stems that have finished blooming should be cut to the ground to promote more colorful new foliage and bloom. Mature colonies (of rhizomes) can be divided while dormant through winter if they get crowded enough to inhibit bloom every few years.