Disclaimer: This post was originally posted by Full Member, LinFL. This user is located in Zone 8b/9a border, NW FL. This was originally posted on April 5, 2014.
Just be sure with the dolomite that it has half as much magnesium as calcium (there should be a chemical analysis on the bag). Sometimes the lime you get at the big box stores doesn't have enough magnesium.
Having said that, so far I have always been able to find the right kind of bulk dolomite (in 40lb or 50lb bags) cheap in the lawn section of either Home Depot, Lowe's, or Walmart. As long as you can keep it dry it keeps.