There are instant read pH meters.

IME, it's neither easy nor practical to change the pH (or the weather.) Accept what you have and get plants that work.

You would want to bring in new planting media that has an acidic mineral component such as crushed granite. pH is largely a function of the mineral content of the soil and so it will return to its natural pH over time If you leave the soil you currently have. You would need to add it on top of the current soil so you don’t get the bathtub effect that would be caused by poor drainage if you dug down to replace soil. The tight knit OH soils (at least everywhere I lived in OH) wouldn’t drain well below the looser rhodie soil so the rhodie soil would need to be raised. With your current soil it would be a lot of work to get it to be well drained and likely have pH fluctuations as you added sulfur and then waited enough for it to break down multiple times over the years.

"it's neither easy nor practical to change the pH (or the weather.) Accept what you have and get plants that work."

That statement sums things up very nicely!! 1) It is extremely diffcult to make that much of a change in soil pH and 2) it will only be temporary at best. Soils will attempt to revert back to their natural state.

The alternative is to grow the acid loving plants in containers or raised beds. It is far easier to import and/or tailor the soil to your specific needs. And because it is not in direct contact with the indigenous soils (or very limited contact), the buffering effect that causes pH to return to its natural state is not present. I would still want to check periodically to assure pH was where it should be.

btw, the consensus with most of the folks that hang out at the Soils forum is that pH meters tend to be only moderately accurate....unless you are investing in the serious $$ scientific models. Drug store test strips or DIY pH kits are remarkably accurate for their cost (use distilled, not tap water) and quick and easy to use.

Generally, where soils are somewhat acidic, you can lime them; farmers here and everywhere do it all the time. (And you can successfully make them more acidic for blueberries, for example, by using soil sulfur.) But where soils are alkaline from say, underlying limestone, you cannot successfully acidify them; the alkalinity rises up constantly. It never works. People on such soils just cannot grow blueberries--or azaleas etc.

Azaleas can tolerate some alkalinity with very little work. My soil is clay with a pH of 7.6 and has not been an issue to azaleas (natives and otherwise) provided I amend the soil once in the Spring with garden sulphur. I monitor the leaves for signs of iron chlorosis but that single amendment application in spring is enough.So I do not aim to lower the pH to levels like 5 to 5.5; instead, I lower them down a bit so the plants do not display iron chlorosis signs on the leaves.

Luis_pr, thanks for the comment. You made my day! Now, I'm going to put this to the test and see what happens. Nothing ventured, nothing gained. I'm also checking with a couple of local nurseries to see what they have to say. I see these plants at their stores each year, but wonder if they are simply potted in the appropriate pH soil and will suffer once transplanted.

Good luck. I have had mine for over 15 years. My Encore started blooming almost a month ago.

There's a popular anecdote about homeowners in Del Rio, TX who insisted on growing azaleas. They hired a landscaper to excavate a trench around the house and backfill with azalea soil. Every few years the pH would creep back toward the alkaline side, at which point the landscaper would repeat the entire procedure. Maybe that's why azalea lovers in alkaline soil regions prefer to grow them in large containers.

How funny! Made my day!

My grandson-in-law tells me that there are some rhododendron varieties coming to market that will tolerate a mild alkaline soil without issues in central Indiana. I'm on his list to get one of each color (only 3) in about 2-3 weeks. So regardless of the colors, I'm going to give it a try and see what happens. Another nursery (largest in Indiana supposedly) told me that rhododendrons and even certain varieties of azaleas are fine in my area as well. So, I'll give an update after I get started with this project. My guess is that is will take a couple of years to see what is going on with the health of the plants, but I'll try to give an honest appraisal. Again, thanks for the many comments.

No. It's a bit easier the other way round (acid to alkaline).