Answer: Yellowing leaves can be a symptom of many problems including overwatering, underwatering, salt burn, lack of nitrogen, iron chlorosis, fertilizer burn, and transplant shock. Although hibiscus are sold in the low desert, they are not ideally suited to our conditions, so even if they seem to be thriving, our harsh environment can take a toll on them. Summer is considered a dormant period for many of the non-native plants that grow here, such as roses. It's best not to "force" them to produce at this time with fertilizer. It stresses the plant and may cause fertilizer burn. Provide protection from the hot afternoon sun and strong winds. Water slowly and deeply, and let the water run out the bottom of the pot to leach salts. "Sprinkling" with water lightly and frequently allows salts to accumulate in the soil, burning roots. Resume feeding when weather cools in the fall and then again in the spring. I hope this info helps.
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