Answer: A strong stream of water from the hose or repeated applications of insecticidal soap will usually discourage aphids so what you've done is what we'd recommend. Insecticidal soap leaves an oily residue so if you apply too often, the leaves can become shiny and hard instead of soft and pliable. This will weather away, or you can try hosing it off. What I do with plants that are sensitive to insecticidal soap is spray the product, wait 15 minutes, then hose it off the plant. This generally rinses off the oily residue. Since insecticidal soap kills aphids on contact, it also gets rid of the dead insects. Give this a try next time you spray your hibiscus with insecticidal soap.
Best wishes with your garden!
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