Canna pretoria is a tropical perennial flowering plant that produces blooms in a variety of colors on tall slim stems over finely striped variegated foliage. Like all cannas they thrive in a full sun exposure and consistently moist soil. Grown from underground rhizomes, canna are very low maintenance and are often planted en masse for a naturalized and dramatic display.
Start bare canna rhizomes by planting indoors in the late winter or early spring. Bury the rhizomes 4 inches deep in commercial potting soil amended with well aged manure and compost. Place each rhizome it its own pot, cover with soil and water in well. Place the pots in a sunny indoor location.
Plant your canna out in the garden after the last frost has passed in spring. Transplant them directly into the ground soil or into large garden containers. Place the plants at intervals of 12 inches to achieve a dense-looking stand rapidly.
Water your cannas regularly so that the soil is kept consistently moist and is never allowed to dry out. Lay down an 1- to 2-inch thick blanket of organic mulch such as shredded bark or cocoa hulls to prevent moisture loss and keep down competitive weeds.
Deadhead faded flowers to promote fresh bloom. Prune away any damaged or diseased foliage or stems as you see them. Prune as you desire to control the size and shape of the plant as canna does not require pruning for growth or bloom.
Feed your canna with a slow-release fertilizer at planting and each year according to the package guidance. Apply over wet soil and water in well.