A neighbor gave me a bag of cannas last fall and it is time to plant them this spring. How do I plant them? Do they have to be in soil? I have seen them in water gardens and was just wondering.
Minnesota Master Gardeners say:
If the rhizomes you received are large (with several 'eyes'), you can divide them in the spring before planting. Each piece needs an 'eye' or growing point; allow the cut pieces to dry before planting.
Cannas grow best in sunny, warm locations. The soil should be rich in organic material and kept moist.
According to http://www.floridaplants.com garden variety cannas will grow equally well in a garden or a wetland habitat. Large self watering pots work well for plants like cannas and taros which like to be well watered. Another option is to make a small water garden out of an old trough or the like, and stand the pots in the water (at least up to their rims) and add a few floating plants as well.
Besides garden cannas there are hybrids called "water cannas" developed at Longwood Gardens that can be used in ponds and water gardens. Longwood water cannas are all 6-7 feet tall with blue green, upright foliage and narrow petalled flowers of various colors. They can be grown in standing water or in the border, and are hardy to zone 6. To find water cannas, search water garden suppliers on the internet for a mail order source, or perhaps you have a local greenhouse that carries a line of pond plants. Some cultivars are: 'Endeavor', 'Taney', 'Ra', 'Erebus', and 'Yellow Princess'. There are also some southern US native canna species which can be grown in shallow water, including Canna flaccida (yellow w/ orange stripes).
Cannas grown in pots in water gardens should be planted in a heavy non organic soil, since soilless mix contains bark and peat which can reduce oxygen levels in the pond, and float out of the pots. (This is contrary to the high organic matter soil required by cannas grown in the garden or pots out of water.) Once water cannas are potted, position the pot in shallow water until it makes shoots, then move the pot to deeper water. When the leaves are up the top of the pot should be 0-8" below the water surface. They are dug and stored dormant in the fall in our area, like garden cannas.
