For a couple of months now, I've been spiking my weekly fertilizer mix with 1/4 tsp/gal of powdered lab grade MgSO4. I've been spraying the whole plant and not just pot watering. I think Antec Bob is a big proponent of foliar feeding. I've seen some pretty obvious greening up with allot of plants, but I've made a couple of other positive observations that are promising for helping other problems in my culture. This is usually the time when I see cases of Erwinia with attempts to add new growths. My wallisii is adding growths without any signs of Erwinia so far. I haven't had a single case so far entering summer. Also allot of moss was getting overrun with blue green algae, and that seems to be abating. It also seems like the leaf spotting on my indoor pleurothallids and phrag leaf tip burn is way down in incidence (definitely no new cases). I'm also seeing much better growth of leaves and roots of my Barbata group as a whole than I've seen in a while.
I found several horticultural articles that said that Mg works synergistically with phosphorous. So the plants can really boost metabolism and carbohydrate production. So more/better flowers and improved disease resistance?!?! I threw all that bone meal all over the place winter/spring, but since starting the mag sulfate campaign things are going great guns.
The same articles also point out that Mg is inhibited by several metals in fairly low concentrations. Namely aluminum, zinc, copper, and manganese. I've read that even high calcium and potassium could slow down Mg uptake.
I know with all the oyster shell and bone meal I use will have plenty of calcium available, and when I'm using Keiki Pro they are getting a zinc spike, and with Superthrive I use potash to raise the pH (a potassium boost).
Anyway it seems like I've tipped the balance to Mg in my culture, and I'll keep up what I'm presently doing as long as growth continues at this rate.
but have not been a regular user . I read quite a bit about it while delving into the fertilizer issue . I had heard a few people say they used it but not a lot.
