Sounds like a great idea to me. Thanks for the tip.

I posted this same questiin in the Tips forum and ended up having to somewhat discount my own idea. While looking up if rust does help, I found quite a few discussions and an article disputing if the iron in rust can even be taken up by plants. So I am first going to try this on a monstera that is starting to show signs of chlorosis.

Yes, that is the correct question. I believe soil pH determines-to a larger degree than just about anything else-the plants' growing there ability to uptake the iron which is present. then again, I live and work in iron-rich red clay. About as different from most FL soils as can be, I'd expect. Iron sulfate can both provide iron and lower soil pH, if that is proven to be desirable by soil test. Straight soil sulfur is what I sue up here to drop the pH. We have dolomite-a type of limestone-underlaying our soil in this part of WI, so for a handful of plant species, the pH can be too high. Not at all your situation but maybe you can glean something from it anyway.

+oM