I bought a spray some weeks ago to put on things you don't want your cat to come near. Costello likes to sharpen his claws on the coach (yes, we need a new!) and this spray really works, but you have to "update" it every two weeks. This spray is a Swedish brand, but I'm sure you have the same spray where you live. Ask in the pet shop. Try to use the spray on the pots.

Here's a list of plants that are toxic to cats and should be avoided.
http://w1.651.telia.com/~u65102970/vaxter.htm
Good luck!