Canna x generalis
- Exotic, tropical creatures, cannas need lots of sunshine and fertile, moist soil but you don't have to pamper them.
- Cannas can be started in the house in small pots if your gardening season is short.
- Where not hardy, plant outdoors in early summer—around the same time you'd put in tomato plants.
- To plant, loosen the soil to a depth of 12 to 15 inches, then mix in a 2- to 4-inch layer of compost.
- Dig a hole 2 to 3 inches deep and set the rhizome in the hole, eyes up.
- Cover with soil and tamp firmly. Water thoroughly.
- Space rhizomes 1 to 4 feet apart.
- If you grow from seed, note that the germination rate is low and the seeds need to be filed or given an acid bath to break down their hard coat.
- Cannas do best with a good supply of water, so water the plants during the summer if the rainfall is less than 1 inch per week. Water freely in a dry spell.
- Keep a thin layer of mulch around cannas to help retain moisture as well.
- Stake tall varieties if needed.
- As flowers fade, deadhead to promote continued flowering.
- Cut each stem to ground after bloom.
- After autumn frost blackens the foliage, remove the stems and leaves, and lift the rhizomes for winter storage. Store in barely-moist peat or leaf mold in frost-free conditions. Space rhizomes so that they are not touching.
- In the deep South, let cannas grow without moving them, until the clumps grow very matted. Every 3 to 4 years in the winter, dig up the clumps, separate the roots, and plant them in well-enriched soil.
- Some gardeners as low as zone 7 have reported that their cannas are getting through the winter without being dug up; just be sure to protect the tubers with a heavy layer of mulch.
- If you are storing cannas over the winter, store in a dry place at 45 to 50 degrees F. Don't let them dry out; sprinkle the sand or soil around them, if necessary.
- In the spring, cut the tubers apart with a sharp knife so that each piece contains one eye on a substantial piece of rootstock.