Hey there, well first off id like to say that some apple snails don't eat live plants.
You should visit Applesnail.net to see if you have a brig snail or a cana snail.
The Canas eat all plants, and brigs will only eat the dead plants.
Im not so sure about the Ramshorn snail.. i think some types might eat it.
Maby if you put salad in the tank, or maby if you buy a cheap plant to test it out,
to see if your snails will eat it or not.
Good luck

,
Alex