The simplest and most humane way to keep cats out of a garden is to lay chicken wire, supported by bricks, over a prized plot. Or sprinkle old holly leaves, pea sticks, or brambles stalks. Where this is impossible, plant rue around the bed. Cats hate it. (Unfortunately, so do all other plants. A beneficial companion, rue is not).
Cats are said to also detest garlic, chamomile, and marigolds. And I have been reliably told that the thorny drag (Ononis spinosa) discourages cats. That advice is totally useless, of course, for those of us who wouldn’t know it with a toilet brush.
However, citronella is also a proven organic cat repellent, in my experience. Spray the edges of the seedlings with 100 drops of citronella per 1 liter of water. Reapply every day until your cats re-educate themselves. Orange, grapefruit or lemon peel is easier to obtain and I have also found it effective.
Chili oil cords, curry powder, garam masala and the like also repel cats. The next idea is a bit controversial. It is also not organic. So if you are a cat lover, I have to be careful (unlike my neighbors’ cats who once used my hotbed as a jogging track).
I surrounded my plot with small plastic milk bottles, sunk in the ground without the lid and each with a few teaspoons of ammonia. It didn’t hurt the cats because none of them got within ten feet of those fierce-smelling bottles.
A powerful cat repellent
Another idea, if you are not picky, is to put dog feces in sealed margarine jars, well perforated on the sides. Place them around your vegetable bed and the cats won’t come near. Neither do dogs. They have a great sense of territory and will not invade another dog’s “land”.
Do not place dog, cat, or human feces, or the feces of other carnivores, on the ground, or even around inedible flowers. The residue persists in the soil and can be toxic. Kids I have go blind after cleaning their eyes with soil contaminated with feces.
Clay granules impregnated with lion or tiger urine are now widely for sale. Said to be nearly odorless to humans, they scare away cats, dogs, foxes, wolves, possums, yetis, and bears. But it is also better to protect them from prying fingers in perforated pots.
If your bird boxes are raided by cats, grow roses and brambles on the trees or posts that support the boxes. Or ask your local fast food establishment for a large empty jerry can that once contained cooking oil and cut it into a metal necklace. Two necklaces will girdle even a large tree. Attach it around the bracket four feet above the ground, the outermost glossy surface, and such a sash will protect bird boxes from cats, squirrels, and young children. Putting it lower will prevent rabbits from chewing on trees.
Practical uses for pets in an organic garden
Small pets sometimes have practical uses. For example, brushed hair from dog or cat blankets (or from horses or any shaggy animal) can be placed in bean ditches to add slow-release nitrogen.
In fact, human hair swept from hairdressers is a wonderful compost bin additive, if you’re not picky. Hanging in net bags around orchards, it will also repel deer and wild boar just as effectively as rotten eggs. (Hydrogen sulfide emitted from poultry egg remains was, in laboratory tests, even more effective at deterring four-legged pests than proprietary repellants.)
Culinary ways to scare cats away
Grow hot red chili peppers in your greenhouse, not to eat, because only Lucifer could taste them, but to grind and soak them in vegetable oil for the winter. Rub this noxious paste on cardboard strips in spring and place them around your seedlings or any other plants you want to protect. Not only will cats excrete, but the smell of fire will also repel many insect pests.
You can also mix an organic (but human) nerve gas 1: 5 with water mixed with liquid detergent, strain and spray on plants infected with aphids, caterpillars and all things that crawl, twist or fly. Kill or dissuade almost everyone.
A fancier cat repellent …
It is made from a discarded plastic glue or liquid detergent bottle. Remove the cap. Throw in several old nylon socks, some glass or rock wool insulation, or even the plastic foam inside of an unemployed teddy bear. This makes a wick. Make sure the wick fits snugly and sticks out from the top.
Fill the bottle one third full with your fiercest human nerve gas (see above) and make sure the wick is soaked to the top. Sink the bottle with your finest plants. The wick will then diffuse the cat repellent into the air.
Several of these bottles in a hotbed, regularly replenished, should deter even Tom and Jerry.
Keep in mind that the above pest repellants will not harm beneficial insects, birds, or any of your pets. Unless they eat them, they won’t. Keep small children away.