My monstera deliciousa got root rot from, what I think, is inappropriate pot size. I got him in March, so almost 2 months ago, left the entire plant untouched, unwatered until all of my soil mix came in. I repotted him in a chunky, well-draining mix of pumice, cactus mix soil, orchid bark, horticultural charcoal, peat moss, and mosquito bits. Earthworm castings came a bit later and I placed a little on top. He was put back into the nursery pot it came in, but the roots weren't as well developed as I hoped, and only reached about 1/3 of the pot depth, which is my mistake.
My question is, what do I do with the left over soil? Should I sift it through for all of the rotted roots and discard them?
I was hoping to sterilize it by pouring boiling water over the whole pot of soil after disposing the rotted roots. I don't want to throw away the soil either because it's expensive
Thank you so much for reading!