I have been growing these Aglaonema pictum tricolor tissue cultures for the last three months. I started them in Coco coir but it was too moist, so I switched them to perlite and then finally a 5-1-1 mix. I had a fungus gnat problem so now I moved them to potting soil amended with perlite. They are growing nicely, but some of the leaves are yellowing on the edges. I did give them a diluted amount of dyna grow foliage pro and am not sure if this burned the leaves. The roots seem to be growing very nicely and I don't have any root rot. Can someone tell me why the leaves are lighter on the edges? Thanks!