Answer: White leaves generally indicate a sudden increase in sun has damaged the foliage. Usually they need to be set in the shade and slowly acclimated to early morning sun, gradually increasing it over the period of about ten days. You need to do it slowly because the leaves become more sun sensitive while they are indoors for the winter where it is relatively dark -- even in a sunny window.
Hibiscus tend to become very leggy, that is their natural growth habit. You can either cut them back quite hard all at once, or you can trim out the longest branches one by one gradually working year round. These plants bloom on older wood so an all over pruning can delay flowering by several months.
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