The tropical canna plants have striking 12- to 24-inch leaves that grow at an amazing rate once the weather warms and send up vibrant, bright red or orange blossoms. These fantastic flowers will bloom all summer until the first frost in temperate zones. Cutting back the stalks and removing the canna bulbs is not a difficult process, but will require about two hours.
Cut back the stems to ground level. Wait to do this after the first frost to enjoy the blossoms as long as possible. Collect the stalks and cut those that are 4 feet or longer again so they will fit into a compost bin. They will decompose quickly after freezing.
Lift and remove with a garden fork the canna tubers that are growing about 2 inches below the surface of the soil.
Rake through the soil to remove any of the smaller tubers that may been have missed. Also keep an eye out for the black, round balls that are about 1/2-inch in diameter. These are the seeds of the canna left behind after the blossoms fade. These could grow into new plants. Remove them from the area.
Watch for any slender green sprouts that show up the next spring. They can be cut or weeded out, but the best approach is to dig out the tubers. After a season of no sprouts, you can be confident that all the canna has been removed from the bed.