Gypsum, how much is needed?

Hey folks, I was wanting to know how to determine the dosage of gypsum to potted plants. I have some plants in veg with the PH being higher than I like (7.5ish) and I have gypsum that I could use, but I dont know how much to add, if i should top dress it, or mix it with water. Any advice on the use of gypsum is welcome, I searched google and bing and I have yet to find any useful information on it regarding potted plants.

add sulfur..........two tbs (in a 5 gal pot) worked in, then watered in. gypsum is alkaline. you need acid.

Oh! Thanks for the info! I will give the sulfur a shot then. I appreciate all the help you provide, this is probably the 10th question of mine you have answered lol

To be extra safe I am going to try 1tbs mixed into the soil and i'll water that in. Thanks again!

sulfur is what i use. glad i could be of some use.

Gypsum does have some sulfur in it, but really doesn't affect pH much one way or the other.

As the New Guinean suggested, the garden sulfur will work better to bring the pH down.

Wet

Hi guys,
I know its a 10 year old post but how much gypsum should i top dress in 3 gallon pots ? I believe i have calcium deficiency and its spreading throughout the canopy.
Any feedback is much appreciated