Answer: Canna lilies often develop brown edges in the low desert. They are native to the tropics and subtropics, so even though they grow here, are conditions are quite a bit less humid than they are used to. Another common problem in the low desert is salt burn. Salts in the water and in fertilizer build up over time. Browning usually occurs on the old leaves first. This excess salt accumulates in the leaf edges, where it kills the tissue and the leaf dries out and turns brown. It's important to water deeply and slowly. At least once a month, water deeply enough to "leach" or push salts well below the root zone. Frequent, light "sprinklings" allow salts to accumulate in the top layers of soil, where the roots are, which is bad news. Similar symptoms occur when too much fertilizer has been applied. Always water plants thoroughly before and after applying fertilizer to help prevent burn.
Also, if plants are in too much direct sunlight, foliage can yellow and then turn brown, as it is basically "burning." Protection from afternoon sun can help, although most cannas seem to be planted in full sun. I hope this info helps!
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