The azalea plants will take whatever cold your area experiences without any need for protection. If the hibiscus is the perennial type it can too, as they die back to the ground and return again in spring. Tropical types of hibiscus plants will be unhappy when temps drop into the lower 50's or below and suffer serious injury and death with a frost or freeze. They would need to be brought indoors or if they are in the ground covered with sheets and then have a source of heat put underneath the covered area.
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