Have some type of protection that can go around your plant.,
If you are using fencing, then make it into a cylinder that will go around your plant and fasten it off.,
Be sure that your catnip is placed into a pot that is sturdy and won’t be knocked over easily.
Put the cylinder/cage over the catnip.
It could be some fencing or a circular (or even a rectangular) bird cage. Anything that serves the purpose will work. If you are using fencing, then make sure that the holes in it, are not big enough for your cat to get his arm through.;
, Zip ties will work pretty well for that. It’s also a good idea to find something for the top. Use the zip ties to fasten it as well.