I have a couple of plants in my frog enclosure, I replaced the soil with smallish pebbles. I pulled them out of their original pot and removed all soil, then washed the whole plant under fresh water to remove any pesticides or chemicals and soil, then re-potted with the pebbles. They're probably the size of my thumb nail, so small enough to fit the tub well but not small enough for the frogs to accidently eat. I use clear plastic trays for them to sit on in the enclosure and use the original pots they came in. I just water them every now and then, usually as I top the frogs water area up.
Frogs like to sit on them, if they're strong enough to hold them, so cleaning frog poo of them is usually the only maintenance. They grow really well in this environment so trimming back may also be required. Otherwise they look great and the frogs love them.