My cats are spoiled - my husband created a large, outdoor cat-safe enclosure for them and they can be dirty to their hearts' content. I have a white, purebred Devon Rex cat who is rarely white anymore.

I say, let her have fun. A little dirt never hurt anybody. Let her be a cat and count your blessings that she uses the litterbox because THAT'S a REAL problem!! Take some pictures of her diggin' in the dirt and share them with us. Our society is too clean imho.

I have the same problem with Bob whom we have had since Thanksgiving. Unknown age, but young and hyper. At first he would only lay in my big pots. The plants are only in side during the winter which is until May here. Now he has started digging in the dirt and he is not to be deterred by water and a puff of air from the pressurized air can only helps for a little while.
My solution is to cover the dirt with pieces of aluminum foil. He still climbs the plant, but he doesn't dig. Can't wait for warmer weather!

Put stones over the dirt.

"old tom" do you mean to say you have a tomcat?. I'd worry about neutering the tom first as tomcat besides being more like urban wildlife then domestic animals spray urine which can lead to electrical fires. Honestly I'm surprised your kitten isn't pregnant. Cats can get pregnant at 6 months. Elderly tom cats can get testical cancer too.

if by "tom" you mean a fixed male then you need to change the choice of worlds- Tom means a breeding male.

As far as plants go, spaying water or putting something in to discourage the cat is about all you can do.

I guess I thought "Tom" was just a male....no, Dudley has been neutered, as has the kitten.

good we have cat named tom also so no biggie