kelgalon:

I'd add some of both. That way you get the fast acting, iron sulfate, and longer term lowering of pH, the sulfur. You are shooting for 4.5 to 5.5.

Ok, great! Thank you! Is it a good idea to wait until the pH is correct to fertilize?

You could add some ammonium sulfate, 21-0-0. It will add nitrogen and lower soil pH. Just be sure to add small amounts and water in well. If you dissolve it first there may be less chances of burning the plants. About one teaspoon per gallon once a week until they are growing as much as you want.

You could also use the complete fertilizer for acid loving plants. Again small doses with lots of water.

You will need to find out the pH of your native soil, and the pH of your tap water, in order to get these blueberries on the road to recovery. Blueberries can tolerate pH up around 6.5 if the soil contains enough vegetable fiber to support fungal activity. They do better with pH between 4.5 and 5.5, however. If you are irrigating these shrubs with tap water, and you have hard water with pH over 7, you can add either white vinegar or sulfuric acid to your tap water, and lower the pH of the water to 5. This must be done with caution, it is easy enough to kill a blueberry shrub with too much acid. If your native soil has a pH over 7, it will gradually raise the pH of your blueberry patch. I use agricultural sulfur to lower soil pH, because it is slow acting and therefore easier to control than other methods. Bromocresol green indicator, yellow at 3.8, and blue at 5.4, is the least expensive way to gauge soil and water pH that I know of. A two dollar bottle of dye indicator might allow 50 or 100 soil tests to be completed.

Ok, I got Dr. Iron for the iron sulfate which is 22% iron and 55% sulfar. I noticed that the iron % is slightly higher when compared to Bonide's iron sulfate which is 15% iron. Is the Dr. Iron still ok to use? I am still looking for the garden sulfur for long term control.

Hmmm, I think I would be using some sort of humic/fulvic acid soil amendment to amend the soil. Sulfur is hard on fungi, and blueberries want a fungal soil. I would use as much wood mulch as you can get your hands on. Perhaps some spruce needles from under a mature spruce tree.

I killed off two blueberry bushes and a spruce with sulfur before I got clued into fungi and fungal soil. Unless I find that my soil needs sulfur, I won't be adding any more to my plants.