Am house/dog sitting for a friend, instead of wasting their dog's drinking water, they want me to pour it on their outdoor hibiscus, and it's R.O. water. Is that OK to do, or does water from the hose contain minerals that plants need?
Dumping a bowl of water onto outdoor plants won't hurt them in the least. RO water does have some minerals in it, but not as many as tap water. I use RO water on all my houseplants and they're quite happy so outdoor plants should be happy, as well.