I was reading in a couple of my books doing some diagnosis on some trees and plants.
For grapes the books say to use a liquid high potassium tomato fertilizer every couple weeks during the growing season. I have gone to Lowes and while I see potassium as a derivative of the fertilizer, I saw nothing that says high potassium.

Also was wondering, where can you find Potassium Sulfate fertilizer? Anyone have any name brands or something that would substitute that is availble off the shelf?

Ill post this in the citrus forum as well but since I am on the subject, anyone know any good Citrus foliar sprays?

I've grown a LOT of grapes, and for over 20 years. I've never heard nor have I ever read about fertilizing grapes every two weeks. Grapes are among the least fertilized crops . - Millet

Ok, this book was specific on FL soil where nutrients stick around until the next rain storm but what do you fertilize them with when you do?