Save leftover citrus peels and grind them up in a food processor. Spread the peels on the soil in your flower bed. The citrus oils repel cats and will naturally decompose. Try spreading used tea leaves or blood meal on your flower beds. Blood meal, an organic fertilizer purchased at gardening stores, fertilizes your flowers while it repels cats with its unpleasant smell.
Grow plants in your garden that are known to repel cats. Grow Plectranthus caninus (Coleus canina), geranium, thyme, lavender, or rue among your other plants. Plectranthus caninus is also known as Scaredy Cat, Dogs Be Gone or Pee-off, but those names do not guarantee that it will work!
Spray commercial animal repellents on your plants. These products contain the urine of predators like coyotes and scare cats away. The downside to these products is that they are expensive and must be reapplied often.
Lay landscaping fabric on top of your soil. Cut holes in it for your plants to poke through. Push landscaping pins through the fabric, around the edges and in the middle, to secure the landscaping fabric. Lay a mulch like wood chips over the landscaping fabric. Cats can no longer get to the soil, and the landscaping fabric keeps the weeds out. Lay a length of inexpensive chicken wire (holes smaller than 1/2 inch by 1/2 inch) on top of your soil. Cats don't like walking on the chicken wire, which can be bought at hardware stores.
Scare away cats by installing a Scarecrow impact sprinkler. Movement activates these noisy sprinklers. A few sprays of the sprinkler may scare cats away permanently. You can also try spraying cats with hoses and squirt guns.