Hi,

I grow almost all of my cannas in big plastic nursery pots and use the soiless mixes like PRO-MIX, Jungle Growth mix, WALMART 's own potting mixes, etc.

They always thrive to the point that they fill the 22" pots by fall!

I also fertilize and water very heavily.

Boca Joe

This year, I planted in large black plastic containers with a 50%/50% mix of MG potting soil and compost. They thrived in that. I added organic matter periodically (coffee grinds, coco bean mulch, etc.) and fertilized once a month. I also interplanted with Lysmachia ('Creeping Jenny' & 'Jungle Green') to cover the black pots and act as a natural mulch. Seemed to help retain the water quite a bit.