Answer: I think a soil test is in order - both azalea and camellia prefer soils on the acid side. If the plants are crowded they may be competing for nutrients, and if they're growing under an eaves where natural rainfall is diverted, they may not be getting enough moisture. It's natural for leaves to yellow and fall at this time of year, even with evergreen plants. (The older leaves are shed after 2-3 years to make room for new spring growth.)
If you decide to prune or transplant, do so in the spring, after the bloom period is over. Otherwise you'll sacrifice next spring's bloom. If the soil test indicates the pH is too high, amend the soil with peatmoss prior to transplanting.
Providing elbow room and rich, well-draining soil, and adequate moisture during the growing season will help your plants regain their health.
Q&A Library Searching Tips