Miracle Gro water soluble azalea fertilizer is more of a problem than a solution.

Azaleas are light feeders. The best source of nitrogen for them is cotton meal. The best acidifier is powdered sulfur. Never use aluminum sulfate, it kills azaleas. Chemicals such as Miracle Gro water soluble fertilizers and ammonium sulfate tend to damage the roots of azaleas.

Thanks for the response, rhodyman.

I also later realized the recommendations from the Extension office include adding Lime at 14 lbs per 100 sq feet.

Oh, I failed to mention that the soil pH is currently 4.7, so I assume that is the reason for the Lime recommendation. Hopefully it is still early enough to broadcast the lime. Does that make sense?

Sorry to have to tell you this but your soil is not suitable for growing Rhododendrons and Azaleas. With levels this high they will inevitably suffer from chlorosis (inability to bind iron). Although there are some treatments available - iron chelates - I feel it would be better to stick to plants that tolerate a high level of alkalinity. A couple of suggestions that are not unazalealike in appearance: Weigela and Kolkwitzia. - Ian.

Thanks, Ian. I expect our initial use of some heavy duty organic compost in that bed before we planted it was a bad idea.

"soil is not suitable for growing Rhododendrons and Azaleas. With levels this high...."

4.7 doesn't even begin to approach alkaline.
The best range is between 4.5 to 6.0. Azaleas and rhododendrons growing in a low pH of 3.5 to 4.5 may be healthy, but will often grow at a slower rate than normal. You might notice symptoms of yellowing and other issues if soil ph is above 6.5, not below.
7 is neutral, above 7 considered alkaline....

Thanks, morz8. Mine have not been healthy over the last two years, which is why we did the soil test. I'll see about getting the pH up following the Lime recommendation first. At least I've learned a lot more about Azaleas and soil chemistry.

If your aren't familiar with growing rhododendrons and azaleas, you might browse through Rhodymans website for practical tips.

Were they healthy previously to the last two years but are in decline now? Has anything changed the drainage, amount of sun/shade, amount of water they might get if not raining?

Here is a link that might be useful: Rhododendron website

Dear andreabwilliams SC,
Are you gardening in South Carolina? If so, Formosa azaleas are widely grown throughout the state. They are the staples of the Charleston gardens, e.g., Middleton Place. Why don't you compare notes with your neighbors regarding how to improve your Formosas? Or contact the horticulturist at Middleton Place to ask his advice. It looks as though you shouldn't be having any trouble with cultivating Formosa azaleas in a state where the soil tends to be acidic and there is an abundance of pine needles to use as mulch.

They were newly planted a few years ago and just haven't thrived. I think it was what we initially put down in the bed. We didn't understand soil chemistry like we do now. And as jay_7bsc says, we thought Formosas would do well here since they are all over the place. I think we tried to get too fancy with the composting and should have kept it simple. Thanks for the tips!

Just a quick update - The azaleas look much better after the Lime treatment.