Worm castings usage
I have added worm castings to my Hibiscus and they thrive but I added also to a small Ficus tree (and two tangerine trees) and they no longer look as healthy as they were. Can the worm castings be the problem - maybe those specific plants do not like them?
Yes, the worm castings could be an issue if they are applied to heavily.
For a small potted plant add approx 1/2" of worm castings to the top of the soil and water in. Repeat every 3 to 4 months.
For fruit trees add 2 cups of castings for every inch of trunk diameter.
Top dress the soil from trunk to drip line cover with mulch and water in.