Soil moisture problems? Azalea roots grow in the top 4", which happens to easily dry out over here during the summer months. Periwinkle may grow into this area and "bother" the azaleas so I would make sure they do not mix. Azaleas need lots of mulch here, 3-4", because of the heat & the winds and to prevent from having to water often. The goal should be to keep the soil as evenly moist as possible. If they get dry periods, followed by moist/wet periods, the plant may dry out or develop root rot (if the soil is left wet for too long periods of time).

So make sure that the shrubs are mulched. Consider adding mulch 6-12" away from the drip line if the area is windy. Then check the soil daily for two weeks at the same time of the day. When the soil feels almost dry or dry, add 1g of water and write a note in a wall calendar indicating that you watered on that day. After two weeks, review how often you had to water and set the sprinkler to water 1g of water on the same frequency (every 2 or 3 or 4... days).

Also make sure that your soil is not caliche or clay because the thin fibruous roots cannot pierce caliche or hard clay. Azaleas need well draining soil and in areas with clay/caliche soil, should be planted in raised beds.

And check the moisture content of the *original* rootball -- feel it. Likely it needs water.