Can Plants Really Repel Cats and Dogs?

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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.

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“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

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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

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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

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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

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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

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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!20180418A big5kayakchallenge.com & domobfdi.deviantart.com

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How Rosemary Got Its Name: A Christmas Legend

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The star of Bethlehem. Source: www.bancodeimagenesgratis.com

When the star of Bethlehem appeared in the sky at the birth of Jesus, all the plants were given the gift of speech. And each wanted to show the others that it could better serve the new king and his family.

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Date palm (Phoenix dactylifera). Source: maxpixel

“I can serve them better than any other plant,” claimed the date palm. “With my long fronds, I can offer them shade during days of sweltering heat. Plus, my delicious fresh or dried fruits will feed them all year long. I am certainly the most useful!”

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Sugar cane (Saccharum officinarum). Source: Ton Rulkens, flickr

“You’re mistaken,” replied the sugar cane. “I’m by far the most useful to Jesus and his parents. With my sugary sap, I can make sweets that will make the child smile, soft drinks to quench his thirst and delicious spreads to butter his bread. I am obviously the most useful!”

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Wheat (Triticum aestivum). Source: flickr

“You’re both wrong!” cried the wheat plant. “Where does daily bread come from, the staple food of all men, if not from my grain? Look how Joseph toils to sow me, to reap me, and to reduce my grains into flour, while Mary bakes not only bread, but delicious biscuits, enough to please everyone. Surely I am the most useful!”

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Rose bush (Rosa sp.). Source: prairieplaces.blogspot.ca

“But none of you can protect the Holy Family against the vile soldiers of King Herod, who threatens to kill all the babies in Bethlehem,” added the rose. “Me, on the other hand, with my sharp spines, I can surround the Holy Family and protect them from any attack. No one would dare cross a hedge of spiny roses! Moreover, my pretty and ever-so-fragrant flowers will make little Jesus smile with joy. It’s obviously me who will be the most useful plant!”

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What could a simple shrub offer to the Holy Family? Source: myfrenchkitchen-ronelle.com

And so each plant expressed itself, extolling its merits. There was only one, a simple shrub, that remained quiet. What could it offer to Jesus and his family? It had nothing remarkable, only simple white and rather dull flowers. Thus the shrub listened to the bluster of others, without saying a word, deeply saddened.

But a few days later, Marie settled out by the well to wash the Holy Family’s clothes. After wringing them out well, she looked for a place to spread the clothes to dry. She tried to spread her wet cloak over the long fronds of the date palm, but they were so high up that she couldn’t reach them. Then she tried the sugar cane, but under the weight of the cloak, its stems bent right to the ground. She didn’t even try drying the clothes on the wheat: its stems don’t even resist heavy rains, let alone the weight of soggy garments. The poor plant would have been crushed! Finally, the rosebush had thorns so nasty that she didn’t even dare to approach it for fear of tearing the clothes.

Then she noticed the shrub. Modest in size, it was perfectly within reach. Interesting! And its stems were rigid and unyielding. In addition, since it was wider than high, there was enough room to support all the clothes as they dried. This shrub just might be the perfect plant to use as a clothes horse!

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Shrub used to dry clothes. Source: peterhousehold.blogspot.ca

Thus, Mary spread the soggy clothes over the shrub, which then swelled with pride, realizing it was at least as useful to the Holy Family as any other plant.

But then a miracle occurred!

When Marie picked up the now dry clothes a few hours later, the purplish blue of her cloak had dripped onto the shrub’s dull white flowers, staining them a beautiful soft blue. Also, the odor of sanctity of baby Jesus’s clothes had permeated the shrub’s narrow foliage, giving it a heavenly aroma. And ever since that day, the shrub bears blue flowers and its foliage gives off a delicious scent that pleases everyone.

Mary, seeing the beauty of the little shrub and breathing in its saintly perfume, exclaimed: “Little shrub, you’re definitely my favorite plant!”

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Rosemary (Rosmarius officinalis). Source: http://www.public.asu.edu

But what is this shrub with its blue flowers and foliage so deliciously scented? Rosemary, of course. Even its name recalls the legend, because the name rosemary comes from the Latin Rosmarinus, which means, of course, “Mary’s rose!”

Merry Christmas!20171225A www.bancodeimagenesgratis.com

A Rosemary Christmas Tree: Doable, But…

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Rosemary plants pruned to look like small Christmas trees.

You may have seen pots of rosemary (Rosmarinus officinalis) pruned to look like Christmas trees in a local garden center or even a supermarket or box store. Since rosemary leaves are very needlelike, their delicious aroma has an almost coniferous smell to it, and the plants have been trimmed to take on a pyramidal shape, the plant could indeed pass for a small Christmas tree… but one with edible “needles”. What a great idea as holiday season decoration!

Except that… very few of the rosemary trees sold in November or early December make it as far as Christmas. In general, few people get more than about 2 weeks of use out of one before the plant dies. And many of those being sold are already in very poor shape before they even leave the store!

The Pros and Cons of the “Rosemary as a Houseplant”

You should know in advance that the rosemary is no philodendron or dracaena. In fact, it actually makes a rather finicky indoor plant.

At the holiday season around the Mediterranean Sea, where it grows in the wild, it would be experiencing full sun, cool days (rarely above 60˚F/15˚C) and cold nights: often just above freezing. It therefore finds our homes very dark and very hot. Plus indoor air is at its driest in the winter while it’s at its moistest in the plant’s natural environment, with a relative humidity that usually stays above 60% whereas in many houses it’s closer to 10%. So your Christmas rosemary is under considerable stress.

That said, if you choose your plant well and place it in the right spot at home, it is possible to not only keep a rosemary Christmas tree in good shape until January, but even throughout the winter.

Choosing a Rosemary Christmas Tree

The most important factor in your plant’s future survival is choosing a healthy one, because rosemary is not a plant that readily forgives mistreatment.

Unfortunately, the rosemary plants sold for the Christmas market are often already in poor condition before you buy them. If the plants you see are have browning, crunchy leaves that drop off when you run your hand over them or they look sparse and their potting soil is strewn with fallen leaves, leave them in the store: they are probably already dying if not dead.

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Soil covered with dead leaves is not a good sign.

Even if the plants’ potting soil is simply dry to the touch in the store, that’s a bad sign: the plant is perhaps already in distress, but may not yet be showing it. The soil should be moist, but not soggy, when you buy the plant.

Ideally you would buy your rosemary tree as soon as it arrives in the store. That is doubly true if you see it in a supermarket or a box store (garden centers, at least, know how to keep their plants healthy while waiting for them to sell!). You can assume freshly delivered plants, at least, have not yet begun their decline!

If it is less than 40˚F (5˚C) outside when you buy you plant, make sure it is carefully wrapped before you take it home. Again, supermarkets and box stores don’t know much about protecting plants, contrary to garden centers. You won’t want any of the leaves to be exposed to cold, so the plant needs to be completely covered. Often that means placing the pot in one bag and covering the top of the plant with a second bag. Accept nothing less!

Finally, don’t leave the plant in a cold car while you continue shopping. Return home with your new plant without delay.

Home Care

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Put your plant near a sunny, cool window… and remove the decorative pot cover or at least pierce a hole in its bottom to ensure good drainage!

If you want your rosemary tree to last a long time, don’t set it on a table in the middle of warm room like you might a poinsettia. It should go directly in the sunniest, coolest place you have, almost certainly near a large window and somewhere temperatures drop to less than 60˚F (15˚C) at night. Place it on a humidity tray or turn on a humidifier to increase the air’s relative humidity.

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Use your imagination to decorate your rosemary Christmas tree.

You’re thinking of decorating your rosemary tree for the holiday season? Go ahead and do it: that won’t harm the plant… as long as you use small, light ornaments that won’t snap off branches and LED lights that don’t give off heat.

If the air in your home is hot and dry, you’ll find that your rosemary tree will dry out very quickly and may need to be watered more than once a week. If the air is humid, it won’t need such frequent waterings. In both cases, though, wait until the soil is dry to the touch, then water thoroughly, moistening the entire root ball. But don’t leave the roots soaking in a saucer of water either.

There is no use fertilizing your plant during the Christmas season: it will be in “survival” mode – just hanging on rather than truly growing – during the winter and won’t be able to use the minerals you provide it.

Watch out for spider mites (read When Spider Mites Invade for more info) and, if you detect any, give the foliage a good shower to remove both the mites and their webs.

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Rosemary suffering from powdery mildew. Photo: Scott Nelson, Flkckr

Unfortunately poor air circulation indoors over the winter sometimes leads to powdery mildew, which looks like a dusty white powder on the plant’s “needles”, almost as if they were covered in really fine snow. It’s actually a fungal disease. Try giving the leaves a thorough shower to knock off the white spores, then spray with neem oil to keep the disease from recurring. You’ll probably have to prune off sections of dead leaves too. Rosemary will recover from powdery mildew, but it often leads to a loss of symmetry that is difficult to cure.

Spring and Summer Care

When the days lengthen noticeably, normally in March, you’ll see your rosemary start to produce fresh leaves. This is the ideal moment for repotting it into a larger container. It was probably growing in too small a pot when you bought it (growers do that to reduce transportation costs: smaller pots mean lighter plants and lighter plants are cheaper to transport), so repotting is certainly due. Any potting soil for indoor plants would be suitable.

You can fertilize lightly (rosemary is not a “greedy” plant when it comes to minerals) as soon as its growth resumes. Any fertilizer you have on hand would be appropriate: apply it at the frequency recommended on the label, but only at 1/8 of the recommended rate.

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Rosemary doesn’t naturally have a pyramidal shape, so you’ll have to prune yours to maintain its Christmas tree appearance.

New growth also means it’s time to begin pruning. Your plant’s pyramid shape isn’t its natural habit. Although come cultivars are more upright than others, rosemary still tends to remain more of a bushy or spreading shrub than a conical Christmas tree. Prune it to shape, cutting back overly-long branches. Repeat every 3 or 4 weeks throughout the growing season. Obviously, any bit pruned off can go straight into the cooking pot!

When summer comes, put your rosemary outdoors. Start first in a shady spot, then partial shade, then full sun, all over a 2 to 3-week period. Do note that outdoor plants dry out much more quickly than indoor plants, especially those growing in pots, so keep a watering can handy. The goal is the same: the soil should always be slightly moist, never either completely dry or soggy.

Note that pruning rosemary to maintain a pyramidal shape means you’ll be pruning off any flower buds and therefore it’s unlikely yours will ever bloom. If you let your rosemary resume its “natural shape”, however, it may produce its attractive little pale blue flowers during the summer.

When Fall Comes

Only in the mildest climates (zone 9) is rosemary going to be fully hardy outdoors, especially container-grown plants, so you’ll have to bring your plant back indoors come September. Place it in a sunny, cool spot and repeat the recommendations given in Home Care above, notably as concerns watering as needed and increased air humidity.


There you go! Yes, rosemary is a capricious plant when grown indoors, especially when it’s pruned to look like a Christmas tree, but with good care, you can keep yours going for many years.20161130C.jpg