how to acidify soil naturally?

I live in the southwest, which has alkaline soil. I have just purchased some low-chill requirement blueberries which I would like to plant in pots, but I will need to amend the soil to make it more acidic. Does anyone have suggestions for an effective homemade way to do this? I keep thinking a very very very dilute vinegar solution would work, but if I'm wrong I'm going to kill the plants. Which would be bad.

It seems to me that agricultural sulfur is as natural as anything can be. It's a simple mineral - in fact an element - that's un-man-made and straight from the earth. Like rock phosphate or greensand..

In the same way that vinegar is sold in a bottle, sulfur is sold in bags.

It works by being biodegraded by soil bacteria that oxidize the powdered sulfur very gradually to sulfate. In the process, it gradually releases acidity. Hence naturally slow-release without even needing to be pelleted and coated.

Some people use vinegar to kill weeds, so don't use too much at once, or too concentrated, or on leaves.

I agree that sulfur should be considered natural, and a good choice. Also add organic matter to your soil, as the blueberries will love it AND it too adds to acidity. Got any pine needles handy? Use them for mulch.

What about coffee grounds diluted composted , sphagnum moss ,, I agree with garden sulfur and organic matter ,
This of course after I lost one blueberry plant) other two looking Good!!!

I have been using the first three . next year (spring) I get to see for sure ..

THose are all good too juhur. ,Remember blueberries are very shallow rooted. Keep the soil moist , and mulch them, and don't dig around them.