Elemental sulfur is insoluble, so it will be more effective if you thoroughly incorporate it. In order for it to lower pH, sulfur has to be metabolized by microorganisms, which takes time -- anywhere from months up to a year or more. Microbial activity declines as soil temperatures decline, so it will act more slowly (if at all) in fall and winter. The only way to know if you need to make further applications is to test the soil pH. Of course, if your previous applications haven't been fully metabolized, you run the risk of adding too much and lowering the pH too far.

This post was edited by shazaam on Sun, Aug 3, 14 at 19:31

That is technical but I understand. The soil I will be using has a pH of 6 to 6.5 so if the highest I could have is 5.4 there is only a difference of six. so you think I only need one application?

If I put sa in the hole will the roots be ok? Do I also sprinkle to on top?

If soil acidifer. Takes too long, can I use Jack's acid?

While Jack's will help to maintain a lower pH over time, it's not suitable for lowering pH in the first place. As for your other questions, I don't know if one application of soil acidifier will be enough or not. All I know to suggest is to follow the directions on the product package and hope for the best. Next spring, check the soil pH. If it's still too high, you might consider adding more. To get the best results, you need to incorporate it throughout the soil as thoroughly as possible. This can be difficult, of course, if you're adding it to pot that's already planted.