Just don't water them too much until they start to leaf out. You might add a little extra perlite to the potting soil.
Susan

Did you grow them in a pot or in the ground?

The biggest challenge in a pot is giving them enough water, unless you have a huge container, in Dallas I would imagine you may need to water several times a day to keep the cannas satisfied...even in the ground they like lots of water in hot weather.

They will only rot if you water too much before leaves are present. Once they leaf out, most cannas can be grown as aquatic plants.

With some of my cannas last year, I started the rhizomes in advance and when they were ready to be planted, I dug a large hole in the yard, put a large black garbage bag into it and then filled it back up with soil and plants...the reduced drainage created a constant wet muck that seemed beneficial to the plants.

Sorry...I thought you asked about "Canna" not "Calla", just ignore what I wrote