I'm just getting into gardening this year, so I'm new to everything, including canna. My sister has lots at her house and we dug some up yesterday and I immediately came home and made a bed for them and planted them. They all vary in size, from about 7 inches to about 20 inches. I watered them well after planting them and this morning I get up and on two of the plants, starting from the tips, the leaves are turning black! Not all the leaves are, just one or two on two different plants. What have I done! Did I damage the roots? What can I do to salvage my canna?