Whats with this cat..hungrey?

we have a beautiful male grey tabby..he is a joy..friendly,happy and loves to play with the dog [omar the chow] and pinkie the angora...a very very content cat..we seem to be unable to have plants or flowers..silk or real...he digs in the dirt,eats the plants and our lovely African Violet is looking ravaged by 'baby' our cat..he give him greens,catnip..a little box of dirt..we spray the pots and plants with a nasty tasting spray to try to prevent his interest..nothing..of course he is an inside cat..i have covered the plants at night..placed the plants up high and still..one silk plant is in shreds..he has a fascination with plants..i love a house with plants and flowers..but baby does also..he loves to chew on a spider plant..when he hears the plant being watered..he cries for a taste. he has his fresh in a pot greens..a little box to play in the dirt..what can i do? he has the run of the house..he has card blanche of the rooms and do not want to confine him..