Can Plants Really Repel Cats and Dogs?

20180418A big5kayakchallenge.com & domobfdi.deviantart.com

In fact, cats and dogs really don’t seem to be bothered by so-called repellent plants. Read on to learn why. Source: big5kayakchallenge.com & domobfdi.deviantart, Montage: laidbackgardener.com

There are lots of blogs and articles on the Internet promoting repellent plants, plants that are supposed to keep cats and dogs away from the garden just by their smell. It’s a most interesting concept, because sometimes our furry little friends do cause a lot of damage in the garden … but do animal-repellent plants actually deliver the goods?

The idea usually promoted is that you simply have to plant repellent plants here and there throughout a flower bed or vegetable garden and then mammals (it seems to be mostly cats that people want to expel*) will then avoid the sector. It’s a concept as old as the world … and yet, positive evidence on the subject rare; I’d even say nonexistent. Many claims, little evidence? That’s not usually a good sign!

Lack of Studies

I have seen zero serious studies on the subject. Not one! There are many about essential oils derived from plants and used to repel insects, but that’s a different story entirely. I was looking for proof that planting certain plants in a garden setting would keep pets away … for an entire season, if not longer! Instead, I found lots of sites claiming this works, but offering no proof whatsoever. Most just seem to take it for granted that repellent plants work, repeating what the author has read elsewhere. On the few sites when there did seem to be some sort of proof, either positive or negative, it always seems to be purely anecdotal, like: “Well, I grow plant X in my garden and I don’t have a cat problem.” Yes, but neither do many gardeners who don’t knowingly grow repellent plants.

20180418H wallpaper.applegreetings.com.jpg

“Nope! No cats in my garden!” Source: wallpaper.applegreetings.com

Most positive posts were from people who tried planting repellent plants as a preventive measure (there were no cats visiting their garden, but they wanted to keep them away) and they’re the first to claim victory. “I planted plant X and no cats have come, so it must have worked!” Obviously, that proves nothing. Maybe cats simply have no reason to visit that garden? Or the owner is not looking at the right time?

Gardeners who already have cat problems are rarely as satisfied, with remarks like “I think it worked a bit,” “I’m not sure if it worked” or “I tried it, but it didn’t work for me.”

Even if you turn to sites hosted by veterinarians, where you think there would be something more concrete, you find a mix of responses. Some simply list repellent plants, but offer no proof, and a few seem to take a more studied look at things and suggest that some plants might have repellent characteristics, but at short distances. Usually, 6 to 8 inches (15 to 30 cm) is the distance given. Essentially, therefore, cats and dogs would only react to repellent plants when they’re right next to them.

My Experiences

A few years ago, I tested a few of these plants on my own pets: my cat Geisha (may she rest in peace) and my dog Maggie, just for the fun of it. This was hardly a scientific study. There were no controls and—who knows?—maybe my pets are just less reactive to scented plants than others? Or trusting of me? Still, I must admit the experiences didn’t lead me to think very favorably about animal repellent plants!

The Piss-Off Plant

The famous Piss-Off Plant (Plectranthus caninus) is more likely to piss off gardeners than cats. Source: http://www.heimhelden.de

I got into this years ago when a plant new to me came onto the market as a cat- and dog-repellent. Called by various trade names, including Scaredy Cat™, Piss-off Plant™, Dog’s Gone™ or Bunnies Gone™, it was said to be Coleus canina, It didn’t take much digging to discover its real name is Plectranthus caninus: an honest mistake, as the two plants are closely related. Its promoters claim it will keep dogs, cats and other mammals (raccoons, rabbits, etc.) at bay.

One seller even invented a detailed background for the plant, claiming it’s a hybrid developed by an Australian amateur gardener by crossing a plectranthus with a coleus, although, in fact, Plectranthus caninus has been growing wild in Africa and India for hundreds of thousands of years. Moreover, when one seller tried to get a patent for this plant (under the name Sumcol 01), the request was denied on the grounds that “the plant presented no discernible difference from the species.”

Despite its unpleasant odor, released when you brush against or stroke the plant’s sticky foliage, there is no evidence that cats, dogs or other animals are in the least disturbed by the presence of Plectranthus caninus. I added one next to Geisha’s favorite sunbathing spot and she just ignored it. In fact, she’d often lean against it when she slept. Nor did she react if I held a cut branch in front of her. I rubbed a leaf with my fingers and held them in front of her muzzle, she did pull her head back, but then, Geisha never did appreciate anyone invading her personal space.

As for Maggie (the dog), she was harder to test, being naturally more excitable, but seemed to show no special reaction when I held a branch in front of her. Placing a pot next to her water bowl didn’t dissuade her in the least, but she did sniff my fingers more willingly than Geisha after I had rubbed the leaves and didn’t seem put off.

My conclusion based in this very limited test what that Plectranthus caninus has no repellent powers whatsoever … on my pets!

The Do About Rue

Rue (Ruta graveolens) is pretty enough, but potentially harmful to humans … and doesn’t seem effective as a cat repellent. Source:www.researchgate.net

I tested rue (Ruta graveolens) at the same time. According to popular belief, it will keep away cats away from the garden, but when I placed Geisha next to the plant growing in my flower bed, she ignored it. I put on latex gloves (rue is phototoxic to many people and should be handled with great care) and tried dangling it front of her nose as she slept. Again, no reaction. Maggie just ignored it as well.

With rue, the question you really have to ask is whether you want to risk causing grievous bodily harm to your family in a probably futile effort to keep cats away? I no longer grow rue since a friend of mine had a painful reaction after brushing against one … in my garden!

Lavender

People love the smell of lavender, but cats seem indifferent to it. Source: www.localharvest.org

Humans consider the scent of lavender (Lavandula spp.) delightful, but it’s actually a natural repellent. The plant produces it to repel insect pests and grazing mammals … but the scent itself isn’t really what keeps them away: it’s the bitter compounds in the leaves that insects and certain mammals avoid. Some websites suggest that lavender will repel cats, but certainly neither of my pets minded it at all. Also, feral cats sometimes cause damage in commercial lavender fields, suggesting lavender has little effect on cats indeed.

Marigolds

Clearly this cat is not bothered by African marigolds (Tagetes erecta). Source: www.solitarywanderer.com

I tested marigolds (Tagetes spp.) at a later date, because I had not heard it was supposed to have repellent effects, at least not on mammals.

Different marigolds have different scents, some attractive to people (T. lucida and T. minuta), others distinctly unpleasant (T. patula and T. erecta). These odors are all designed to repel insects, or at least, to keep them from eating the plants. You see, the plant really doesn’t want to repel insects: it needs pollinating ones to ensure its flowers are fecundated. In fact, marigolds are widely used in companion planting to attract pollinating insects. It only wants to keep insects from eating its leaves. So its taste is repellent; its scent, not so much.

Geisha and Maggie both found marigolds (I tried T. patula, T. erectato and T. minuta) be of no interest whatsoever and were neither rebuffed nor attracted by them.

And the Others

The curry plant (Helichrysum italicum) smells like curry and that doesn’t seem to bother cats. Source: flipper.diff.org

I suspect that, if any plant that has a scent, somebody somewhere will eventually claim it repels cats (and maybe dogs). Here are some other plants that have that reputation, but didn’t work on my pets: curry plant (Helichrysum italicum), rosemary (Rosmarinus officinalis) and pennyroyal (Mentha pulegium). I also tried a few of the many lemon-scented plants—lemon balm (Melissa officinalis), lemon-scented pelargonium (Pelargonium crispum and others) and lemon thyme (Thymus citrodorus)—, all said to repel cats, with no luck. I stopped testing after Geisha died, as we no longer have a cat to use as a test subject. (My wife has developed a serious cat allergy, so Geisha was not replaced.)

How Believers Can Use Repellent Plants

If you still believe that plants have a significant repellent effect on cats and dogs, calculate their effect is limited to a distance of 6 to 8 inches (15 to 20 cm) from the plant. Therefore, the method most often recommended, that is, planting them here and there among garden plants you want to protect, is simply not going to work. Any repellent effect would be too diluted and cats would simply have to wander around the individual repellent plants to get their favorite spot.

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For a repellent plant (here, Lavandula angustifolia) to be effective, you’d really need to use it as a barrier plant. Source: www.gardenscentsations.com

Other sites suggest a more likely method: using them as barrier plants, that is, surrounding the zone with dense plantings felines can’t find a way around. One site recommends using taller repellent plants as being more effective, as cats simply jump right over short ones.

Personally, the cats and dogs in my neighborhood never bother my garden, so I have no need for any kind of pet repellent. If I did, given the results of my experiments, you can be sure I’d try something other than repellent plants!

Read Keep Cats Out of Your Gardenfor a few methods that really work!

Do Animal Repellents Really Work?

Animals and birds are cute as buttons, but what damage they can cause to gardens!

Probably every gardener will have to deal with an undesirable animal or bird at some point: a groundhog grazing on their broccoli, birds eating their seedlings, a cat using the vegetable bed as a litter box, and so on. If so, no worry: there is a whole range of animal deterrents you can try, products that are supposed to drive them away. But are they effective?

There are dozens of these products on the market and just as many homemade deterrents: plastic owls or snakes, silver ribbons or aluminum pie plates that move in the wind, systems that produce loud noises or ultrasounds, stinky products like rotten eggs, predator urine and animal fur, good old-fashioned scarecrows, and the list goes on.

Deterrents function by scaring mammals (and also birds in some cases): they make the animal feel that there is something strange or abnormal going on and it feels threatened, staying away for a while. And that’s where the problem lies: there really is no threat and, once the animal realizes that there is no real danger, it comes back to its former haunts.

The secret, therefore, is not to have a single repellent or deterrent, but several, and to use them in rotation. Normally, a deterrent will be effective for about two weeks. That means you’ll need a whole arsenal of repellents if you want to spend a summer in peace.

Here are a few:

A scarecrow will work for a while … but not the whole summer! Photo: En: User: Fg2, Wikipedia

Aluminum plates or metal cans attached to strings so they bang together in the wind;
Animal decoys (owls, snakes, hawks, coyotes, etc.);
Bits of cloth soaked in creosote;
Blood meal or chicken manure (and they’re fertilizers too!);
Bright light set off by a motion detector;
Cat or dog fur (get some from a pet groomer);
Commercial animal repellents (Plantskydd, Bobbex, etc.);
Garlic spray;
Highly perfumed fabric softener sheets;
Human hair (ask your hairdresser to save some for you);
Irish Spring, Dial or any other strongly scented soap;
Loud music;
Moth balls (be careful not to leave them where kids or pets can get to them!);
Motion-activated sprinkler;
Predator urine (coyote, fox and even lion urine can be purchased);
Recordings of explosions or rifle shots;
Repellent plants (dill, chives, garlic, lavender, onion, oregano, Russian sage, tansy, tarragon, thyme, wormwood and yarrow are examples: they’ll avoid these plants … for a while!);
Scarecrows;
Scare-eye balloons;
Shiny ribbons that dangle from branches or wires;
Sprays made from rotten eggs;
Treated sewage sludge (Milorganite, for example);
Ultrasonic devices (actually, though widely available, they have not been found very effective);
White rags that move in the wind;
And so on.

Note that many of these repellents smell so badly or make so much noise that you won’t want to visit your garden either!

The Only Deterrent That Works Long Term

A motion-activated sprinkler will scare pests away every time.

Other than properly installed animal fencing (very expensive and difficult to properly install, but permanent and effective), the only simple deterrent that keeps most animals away in the long run is the motion-activated sprinkler. The animal approaches your garden and gets sprayed. True enough, it’s only with water, but … something has touched it and that is something no animal seems to be able to get used to. Deer, raccoons, cats, dogs, squirrels, rabbits, groundhogs, even crows and pigeons: they’ll all stay away from a motion-activated sprinkler.

Obviously, the device is not effective against animals that live underground, such as moles, and doesn’t react to very small animals: chipmunks, mice, most birds, etc. And at about $70 per device, it’s quite expensive … but at least it works and thus you rarely hear a user complain about the price. Apparently peace between humans and animals is worth any expense!

Stinky Herbs Repulse Pests

Have you ever noticed that herbs are rarely affected by insects? Or even by mammals (groundhogs, deer, etc.)? There’s a good reason for that. It’s because the same aromas that we humans consider so attractive in herbs – they come from essential oils in their leaves – are actually natural repellents, designed by Mother Nature to keep away insects and other pests that would would otherwise eat the plant. That’s why herbs are generally less subject to pests than other plants.

Acceptance of herbal aromas is not innate: you have to get used to them!

Moreover this dislike of herbal aromas even extends to humans. Most babies instinctively push away herbs when allowed to handle them and will make faces or spit them out if they are fed to them. (Curiously, though, if mom regularly consumed a certain herb during her pregnancy, baby will already be accustomed to it before birth!). It’s by giving babies small amounts of various herbs that they come to accept and even to like them.

Moreover, even adults generally dislike aromatic herbs introduced from elsewhere and to which they have not been exposed in the past. Many adults from northern North America have never gotten used to cilantro, ubiquitous in Mexican foods, as the herb has only really been used in their area over the last 20 years.

Thus herbs really are natural repellents: we find their odor unpleasant at first. Only over time do we come to love their smell.

Using The Repellent Effect of Herbs

The gardener can turn the repellent effect of herbs to his advantage by planting them among plants subject to insects. Planting basil, garlic or lavender near tomatoes or lettuce, for example, can reduce infestations. A little. Sometimes. That’s because other factors also come into play. Especially growing conditions! A plant stressed by drought or lack of minerals will attract enemies regardless of plants that accompany it. And a really hungry animal will overcome its natural repulsion and nibble heartily on a vegetable surrounded mint or lavender.

No one knows whether it’s the aroma of herbs that repels pests or whether their very intense smell instead camouflages that of neighboring plants. But the result is the same: fewer pests!

However, there are exceptions to the rule that herbs repel pests. There are a few pests who are specifically attracted to certain essential oils. Some whiteflies, for example, seem to prefer herbs to any other type of plant!

Laidback Gardener Tip of the Day

A Plant that Repels Cats and Dogs?

Sometimes you’ll see plants that are that are supposed repel cats and dogs and keep them out of the garden due to their repulsive smell. This is an interesting concept because sometimes our furry friends do cause damage in the garden, but… do these plants really work?

Plectranthus caninus

A plant that is sometimes offered as a cat- or dog-repellent is so-called Coleus canina, which is sold under various trade names such as Scardy Cat™, Piss off-Plant™, Dog’s Gone™ or Bunnies Gone™. This is actually Plectranthus caninus and it’s supposed keep dogs, cats and other mammals (raccoons, rabbits, etc.) at bay. One seller even invented a pedigree for this plant, claiming that it is a hybrid obtained by an Australian amateur gardener by crossing a plectranthus with a coleus, although, in fact, Plectranthus caninus has been growing wild in Africa and India for millennia. Moreover, when one seller tried to get a patent for this plant (under the name ‘SUMCOL 01’), his request was denied on the grounds that “the plant presented no discernible difference from the species”.

Despite its unpleasant odor, released when you or the animal touches the plant’s sticky foliage, there is no evidence that cats, dogs or other animals are in the least disturbed by the presence of Plectranthus caninus. My late cat Geisha used to like to sleep in its pot and my dog Maggie simply ignores it.

Rue (Ruta graveolens)

However, there is rue (Ruta graveolens) that apparently repels cats (but not dogs or other mammals). It seems that it is effective in some cases and not in others, depending on the cat’s sensitivity. The problem is that rue often causes burns to humans, as it gives off phototoxic furocoumarins. By phototoxic, I mean that burns only appear when the skin is first exposed to the plant and then to the sun. When the sun is not present, such as in the evening or on cloudy days, there is no unpleasant reaction. Moreover, rue is used as a medicinal plant and even a condiment in some countries, although it should be used very sparingly, since it can cause gastric problems or even death if consumed in important quantities.

The repellent effect of rue is however very limited, covering only about 6 to 12 inches (15-30 cm). To protect a garden from cats, assuming your local cats are sensitive ones, you’ll need to literally surround the bed with rue plants.

Rue is a short-lived perennial, lasting 4 or 5 years, and is hardy in zones 4 to 9. Before planting rue, check to see if it can be legally grown in your area, as it is banned as a noxious weed in some countries.

To learn how to effectively keep cats out of the garden, see the Tip of the day of 14 November 2014.

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A Plant that Repels Cats and Dogs?

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