I recently added gypsum to my soil to combat heavy clay soil then planted a snowfake hibiscus and a syzygium, the hibiscus died and the syzygium struggle but is ok now. Does gypsum effect plants?
Can Gypsum Effect Plants
Certified GKH Gardening Expert
Mostly no, but if large amounts are added to the soil, it can create a few nutrient deficiencies. Gypsum can reduce the amount of iron, manganese, magnesium, phosphorus, copper and zinc a plant can take up, but it would have to be a pretty large amount of gypsum to do this.
Gypsum is much like any other soil additive. The right amount is good, but too much can cause problems.