I recently received a request for an article on plant ideas that would dissuade cats from visiting the garden. So at the risk of upsetting the #CatsOfCandide, who are a beautiful and fluffy part of our community, I thought I would oblige, as occasionally we want to keep cats out of the garden.
The most well known and effective plant is commonly called Scat. (Plectanthus caninus) This annual plant can get to about 60cm (2') high and has dark green foliage that shows off its pretty blue or purple flowers. Its leaves give off an odour which cats (and dogs) find repellent. You can grow this as a small hedge around areas you want to protect or dotted through borders amongst your perennial planting.
Like Scat, herbs with strong scents may also deter some felines from sunbathing on top of precious seedlings or emerging foliage. Try interspersing these attractive plants throughout the garden.
A plant that is included on many lists as being a good cat deterrent is rue. This shrub can get to 60 to 90cm high and has scented leaves that can also be collected, dried and spread over areas you want to keep cat free. However, a word of warning must be included. You will need to handle this plant with care as its sap can be a skin irritant. It is also toxic if eaten, but most cats know not to!
Prickly shrubs can create more substantial obstacles, and these can be planted as hedges or in boundary gaps.
Unfortunately, these will only work roughly 70% of the time. Some cats are so determined on gaining access that they'll not be put off by anything. For sensitive areas, you may need to use additional support.
Remove all fouling to prevent others from copying. As they are carnivores, cat mess can contain parasites and pathogens which isn't recommended for soil, especially in vegetable patches.
Newly prepared seedbeds can be covered with chicken wire-covered frames to prevent them from being scratched up or used as litter trays.
Inserting canes through the middle of bronze leaved grasses such as Carex comans will prevent the turfs from being flattened.
Mulching the bare ground around plants with prickly items such as coarse bark, twigs, pyracantha prunings, pine cones, conifer needles and holly leaves (although not much fun for the gardener) will provide some protection. Cats prefer soft, malleable soil to walk on and dig up.
Although I have no personal experience, many people recommend using chopped up citrus (orange, lemon, lime, grapefruit) peel scattered around plants. The citrus oil is unpleasant to cats.
My favourite deterrent, the scent from a canine companion will soon persuade feline neighbours to stay away.
Light reflecting scares are an old gamekeepers trick, which is why you may see half-filled bottles of water placed between plants or unwanted CD's hanging across flower beds and borders.
In one garden I care for, an electronic scarer emits a high pitch sound to helped protect a regularly used nest box. There are other devices available that detect movement, and either spray water or emit light to frighten off inquisitive cats.
Over time, cats will get used to all of these methods, and you may need to change tactics, use several of them or get a tomcat of your own. My one suggestion as a gardener would be to plant catnip and place a litter tray nearby. With all these conveniences at home, they may not feel the need to stray!