I am not getting a clear idea of how much water they are getting now in the hot summer (where are you located?) or how much sun.

Their roots are usually on the top 4" of the soil (mulch not included) so try to water when this area feels dry or almost dry. Depending on soil type, weather, etc, you may need to water anywhere from a few gallons to twice as much. After you water, wait for the soil to drain and then test the soil in multiple places to a depth of about 8".

If the plants are getting too much sun (leaf damage is concentrated on leaves in direct contact with the sun) temporarily add some more shade.

Azaleas and rhodies are not heavy feeders like roses so if they already came with those round fertilizer pellets, I would not fertilize again until Spring 2021. Besides, they do not require much fertilizer during these hot times. After they become established, they can feed off decomposing mulch if you maintain 2-4" of organic mulch (no rocks) year around.

I also have an irrigation system and when the Kentucky bluegrass lawn is watered, these plants get watered as well. I usually water late in the afternoon, early evening, or at night.

==>>> you can not waer deeply.. into the root mss by relying on lawn irrigation .. as lawn roots are not as deep as shrub roots ...

i also would not be wetting foliage every dy. especially when nights and mornings are so dewy ...

if it were me.. i would remove them from lawn spraying ... and i would insure proper watering by digging some small holes.. and FINDING OUT ABOUT MOISTURE at depth ...

i would also suggest a soil test to determine pH and then adjust such accordingly with soil amendments .. and not rely on fertilizer for such ...

imo .. once the pH is proper... well established shrubs most likely will not need any further fert ...

it takes a year or two.. or proper watering.. to get a shrub fully established ... perhaps it is a sign.. that the recently planted shrub is struggling ...

lack of proper water.. will lead to leaf damage ... which then can cause other problems... but unless you solve the base or primary issue.. then attacking secondary issues.. wont help ...

ken

Laceyvail, what is the minimum acidic number for azaleas and rhodies that a gardener could prudently start with? In other words, if the soil is above this number, it's probably best to find a non-ericaceous plant. Lilac?

Rhododendrons and azaleas need an acid soil with a pH of around 4.5 to 6.0 (ball park) and well mulched soils with organic material. They thrive in an evenly moist, well-drained, humus-filled soil, enriched with leaf mold. But they tolerate alkalinity... up to a point, of course. In my alkaline 7.6 pH clay soil, I use a lot of organic matter and they tolerate it with annual Spring amendments of garden sulfur. You need to get a soil test done to see what your soil pH is. If you do not want to annually amend the soils, you could switch to lilacs (different height for starters though, and incredible fragrance!). Hee, hee, hee. If you get a lilac, try one of the rebloomers.

It’s often stated to always plant in native soil (i.e. no amending), but I don’t think it applies with azaleas. Otherwise, wouldn’t success with azaleas be limited to very few gardeners?

For what it’s worth, I recently planted three azaleas from the Northern Lights series. Since azalea roots are very shallow, I dug the hole about three times as wide as the root ball, but angled so it was only slightly wider at the bottom. It was then filled with an equal mix of native soil, compost, and commercially obtained garden soil. I did a soil test, which appeared to be between 5.5 - 6.