Many of the leaves of my Westerland look like this (very reddish tips, not browned), but I also have a potted Pretty Jessica with yellow tipped leaves. Westerland is in ground though. I had a soil test done and my soil is low on potash, maybe this is one of the symptoms? My soil right now is also low on nitrogen though, of course, because we can't fertilize now.

Westerland red leaf tips:

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Westerland yellow leaf tips:

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Pretty Jessica yellow leaf tips:

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