Miracle-Gro and other chemical fertilizers might stimulate new growth, but they don't do any long-term good. They make plants more susceptible to desease and attack by insects. Chemical fertilizers also destroy the microbiotic life in the soil.

Get an organic fertilizer and/or some more organic material. At the Lowe's and Home Depot stores in my neighborhood there is a more expensive manure that is much better than what they call composted manure. It's called "Black Cow" and comes in a yellow and black 40-pound bag. More poop, less filler - your cannas would love this stuff.