August brings heat and humidity, with frequent daily thunderstorms that may wreak havoc on summer-flowering perennials. Canna lilies are an exception, thriving during the dog days of summer.

Its flowers range from 4 to 8 inches long and appear on the ends of the stem as racemes or panicles. Cannas bloom during the summer months, from July to August. Depending on the cultivar, Cannas show ...