Answer: Browning leaves on cannas are usually a sign of water stress. Cannas prefer full sun and a very rich, moist soil. You might try repotting them into fresh soil and use some of the waterholding polymer in it to help keep the soil evenly moist. If they grew in the same pots last year, the rhizomes will now be much larger than they were when you planted them so you might want to either divide them or move them to larger pots. This would help reduce the chance of moisture stress. Then place the pots in a sunny location. The leaves could also be showing a delayed response to cold damage if they were exposed to some colder nights earlier in the season.
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