A few years ago, our neighbors asked us to take care of their houseplants. They spend the winter someplace a lot warmer than Sandpoint, and they didn’t want to drive their three huge spider plants halfway across the country. So we agreed to tend to the plants over the winter. Spider plants make great hanging plants and we already had hooks in our ceiling, so the plants could hang in front of our picture windows.
Unfortunately, we also have cats. By the time we gave the plants back the following Spring, the plants had no little "spiders" or leaves hanging off the side that was closest to the window. One of our cats apparently spent most of the winter launching off the windowsill and dive-bombing the plant. Needless to say, our neighbors have never had us plant-sit again.
Plant eating is actually a normal feline behavior. Cats eat grass and other plants because it’s good for their digestion. And of course because they like eating plants. Given that cats are the ultimate hedonists, you’re going to have a lot of trouble convincing a cat not to eat your plants. You’ll be fighting feline instinct and desire, which is not a good thing.
As with most kitty-behavior issues, diversion is probably your best bet. You can buy seeds for grasses cats like to eat at many pet stores. Or if you don’t want to get an official seed "kit," try planting some wheat grass or catnip in a tray or flowerpot, so your cat can have her own private snack bar. The idea is that if the cat has her own little garden to munch on, she’ll avoid your other houseplants.
If diversion doesn’t work, you can also try deterrents. Pet stores sell non-toxic, bad-tasting concoctions that you can spray on the leaves of your plants. However, you should read the label carefully as some sprays can hurt the plant.
Keeping your cat entertained (not to mention tired) also can keep her from chowing down on your plants. A sleeping cat is not committing acts of kitty badness. So play with your cat and make sure she’s got a scratching post and fun toys to keep her amused.
Finally, when you buy houseplants, be sure that they are not poisonous to cats. If your cat is an inveterate plant eater, she may not be particularly discriminating. A few common plants like philodendrons and poinsettias are toxic. Your vet may be able to give you a list of plants to avoid, or you can find a list online at the Humane Society Web site at http://www.hsus.org/ace/11777.