Cannas are native to the northern and southern hemisphere. However, they do well over most of the United States provided there is plenty of heat. Cannas are very dependable-- easy to plant and easy to grow.
Cannas should be planted in spring after danger from hard frost. In zone 7 we recommend planting from March 15th to April 15th. Adjust the guideline to your zone. Before spring planting, soil can be amended with compost, manure, and a low nitrogen fertilizer similar to 6-12-12 analysis. Best results are achieved when planted in a loose, well-drained soil. However, they will tolerate a wide range of growing conditions.
Plants bulbs 12 to 18 inches apart. Lay long part of the bulb horizontal to the earth’s surface with eye up, if visible. This is not critical, as cannas will grow no matter which direction they are planted. Cover with 2" of soil. In colder regions, (6-8 weeks before spring), bulbs can be planted in pots and placed in greenhouse conditions. When danger of frost is past, remove from pot and plant outside. Cultivate often to keep soil loose and free of weeds.
Cannas should be watered thoroughly once a week by slowly soaking the area around the roots. For optimum performance apply a foliar fertilizer, such as Miracle Grow, twice a month. Although cannas will continue to bloom if not dead-headed, cutting old spent flowers and seed pods will make them prettier and neater in the garden.
Insects rarely bother cannas. Leaf-feeding insects and leaf-rolling caterpillars can be stopped by regular applications of Orthene.
Cannas will multiply producing three to five bulbs for each one planted. Dig clumps of bulbs in late fall or after the first frost for re-planting the following spring. Two methods of storage are:
1. Remove old stalks, leave bulbs in clump with soil intact. Pile clumps and cover with plastic and store in basement. Never store in mesh bags as that will allow bulbs to dry out.
2. Bulbs can be washed, divided, dried and layered with peat moss in waxed boxes with lids or in plastic bags, with a few air holes, to prevent drying out. Store in basement or other cool place such as a garage, under the house, in a well house or cool room. Bulbs must not be allowed to freeze during storage. The ideal storage temperature is between 50 and 60 degrees.
In zones 7-10 where the ground doesn’t freeze below four to six inches, cannas can be left in the ground all winter. Leave old stalk intact and cover clump with 6-12" of grass clippings, leaves, compost, cotton burrs, etc. However, old clumps should be thinned in the spring every 1-2 years by digging out thick areas of bulbs to space bulbs to about one foot apart.
Information supplied by commercial canna grower and wholesale shipper Horn Canna Farm