@topaz definitely don't dump it on the plant unless you want dead plant.
Boiling water isn't great for plastics either. I doubt you'd melt it or anything but it's not going to be good for it. Is the ground next to the plant off-limits?
otherwise yes the steel will work much better
@topaz steel it is!
@Doephin oh we'd still have to dump the mixing bowl somewhere >,,>
@Doephin ... oh I bet leaving it in the dishpan or the mixing bowl before dumping it should let it cool down some. That would probably be less bad for the plant.
@Doephin ...the ground next to the plant is bare concrete with no drainage. (When it rains it floods and it's awful.) We've been trying to dump it in the side of the pot, where there's no plant, but... yeah.