I see on the net many references to using vinegar to acidify potting soil for blueberries.
Has anyone try this with roses, and what were the results?
All I can say is that acetic acid is a perfect carbon substrate for many bacteria. So don’t expect it to hang round in the soil more than a few weeks. I’ve grown blueberries for decades in an area with pH 8 soil. First I used a bale of peat for each plant. Later I added pounds of ferrous sulfate. The iron precipitates after oxidizing to ferric iron, and the sulfate acidifies. Some people use alum which is used in water treatment plants to flocculate excess minerals. The Al precipitates and the sulfate acidifies. More recently I have used pine needles and the stuff that falls off baldcypress in the autumn (mixture of needles and small twigs). Blueberries grow in the pine barrens of New Jersey and around Brookhaven on Long Island so I knew they could tolerate the acidity of needles.
Powdered citric acid works well, too. You have to get some pH test strips to help you get in the ballpark. For my water here, it’s about 1 teaspoon citric acid powder to three or four gallons of water.
Citrate lasts a little longer than acetate but not much. It was tried several decades ago to help plant remove heavy metals from soils, testing the theory that plant that make citric acid and excrete it into the soil are able to take up the unwanted metal better.But what happened was that there were organisms (fungi, bacteria?) that got better and better at eating up the citrate. So it didn’t hang round in the soil for long. Paul Schwab, who left K-State for Purdue did work on that stuff in the 1990s.
The same thing happens to commercial buffers when they come in contact with the soil, or unsterile water. They get degraded. I learned the hard way by killing a bunch of plants with different buffers. In sterile water they are OK. But for us, stick with inorganic pH controllers such as I mentioned to precipitate the calcium and magnesium of alkaline soils.