11 Garden Plants That Repel Rats & Mice
Although tiny critters are staple visitors of rural or naturalized backyards, some of them can be troublesome and dangerous. Field mice may seem tolerable, but their curiosity often leads them inside the home, where they can destroy furniture and drive a pet crazy. Rats, on the other hand, can be an absolute nuisance as they tend to carry diseases and fleas. They are generally larger than mice and can quickly reproduce to infest dry and dark areas.
If you spot a combination of the following signs, it is likely that rodents regularly visit your garden: grain-sized and dark brown droppings in numerous spots, nesting areas under woodpiles and mulch, partly eaten fruits and vegetables, small footprints, burrows close to a source of food, and urine scent trails. If you have a dog that insistently sniffs around potential nesting zones, it’s likely that a rodent or another wild animal has been there.
Gardens that are full of seed-producing plants, vegetable beds, and fruit trees will inevitably attract these animals. They predominantly rely on these plants for sustenance, though they will not hesitate to feed on waste if it is readily available.
Apart from properly storing food, maintaining your garden’s tidiness, and keeping your trash cans shut at night, you can plant the following species to help dissuade unwanted visitors. As much as possible, avoid invasive plants as these may increase the chances of infestation by altering the ecosystem structure.
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1) Chrysanthemums (Chrysanthemum spp.)
A rat-repellent garden need not be devoid of large blooms in a wide array of eye-catching colors. It can be dotted with chrysanthemum beds and borders! These stunning plants of the Asteraceae family come in hundreds of cultivars. As they are incredibly popular, you’re more than likely to find a few in your local plant nursery or garden store. The best time to acquire them is before or during fall, which is when they come into bloom.
Chrysanthemums are great against rodents because their blooms contain a unique combination of insecticidal compounds. These work against rats in the same way that they can be lethal to insects, though a more severe type of exposure may be required for these larger mammals. The flowers’ yellow centers are laced with pyrethrin, now considered the most important natural pesticide in the world.
As pyrethrin is organic and safe for farmers to use, they can simply dry chrysanthemum blooms to manually collect the substance. For the plant to be effective, however, its stands should be regularly maintained to prevent it from attracting its own host of pests, such as thrips and nematodes.
2) Onion (Allium cepa)
The strong smell of onions can function as a temporary deterrent to rats, which are sensitive to spicy scents. While many of us can appreciate and savor the taste of this popular root crop, some small mammals can develop an adverse reaction after consuming it. A small dose of raw onion can be fatal to rats when it is ingested.
Rats will seldom voluntarily consume raw onions. They may make an exception, but only if the scent is masked by other ingredients or if it is mixed into meaty dishes. Moreover, cooked onions are not poisonous to rats as their toxic contents are denatured by heat.
That being said, raw onions in the ground may not be the most effective repellents on their own, particularly if their skin is fully intact. They will need to be cut to expose their spicy aroma. You may consider incorporating finely chopped pieces into an organic pesticide, which you can spray around parts of the garden where rat droppings and burrows are spotted.
3) Rosemary (Salvia rosmarinus)
The use of rosemary as a decorative plant, culinary ingredient, source of fragrant oils, and medicinal herb goes back centuries. This economically important crop is a remarkably hardy plant with succulent-like foliage. As a perennial, its shoots can persist through mild winters as they naturally grow dormant. Thus, it is an ideal, all-around pest-repellent plant in temperate zones.
The unmistakable fragrance of rosemary leaves, which is strengthened where the leaves are cut or scarred, can deter curious rodents. Intact leaves on considerably-sized bushes may still be effective as long as they are situated in the right areas, such as along pathways and close to fence gaps that may be frequented by wild visitors.
If your pets and children often play in your garden, this is a fairly safe herb to cultivate. Rosemary is largely ignored by dogs and cats, and a considerable amount of the plant must be ingested for undesirable side effects to occur. You can distribute cut sprigs of rosemary or even spray rosemary oil around doorways and windows through which rodents may attempt to enter the home.
4) Elderberry (Sambucus spp.)
Elderberry plants are frequently cultivated as ornamental perennials due to the favorable appearance of their flowers, fruits, and foliage. Species that are popularly used in the West for medicinal purposes include the American elder (S. canadensis) and European elder (S. nigra). These grow into shrubs that can measure anywhere from 4 – 15 feet (1.2 – 4.6 meters) tall at maturity.
Elderberries produce black to red berries, some of which are toxic to humans. Fruits of the more common species can be safely consumed in cooked and fermented foods, but their bark, leaves, stems, and roots are usually unsafe. Elderberry extract from the fruits and bark may be toxic to rats and other mammals when consumed in large doses.
Rodents and larger wild mammals generally stay away from elderberry shrubs, so these may be ideal border plants for the garden. Glycosides in S. nigra are particularly known for being dangerous, though they are also associated with medicinal benefits when applied in the right doses. Avoid planting elderberry shrubs in your garden if it is frequented by pets and children.
5) Christ plant (Euphorbia milii)
The Christ plant, which is also widely known as crown-of-thorns due to its spiky shoots, is a well-known ornamental species. It is quite hardy, resistant to diseases, and does not require much in terms of maintenance. Its strong shoots can grow up to 5 feet (1.5 meters) tall in optimal conditions. The largest specimens can be challenging to handle by hand due to their sharp spines.
As a pest repellent, this plant’s effects are two-fold due to the combination of its external and internal features. Of course, the spines keep many soft-bodied animals away. The sap exuded by cut stems is toxic even to large domesticated animals, so rodents are not immune to the severe irritation it causes. The sap’s toxic profile likely developed as a protective adaptation against potential grazers in the wild.
As a rodent repellent, the Christ plant need not be mechanically damaged to expose its sap. Its spiny shoots just need to be grown in an intact arrangement to serve as a relatively impermeable wall. If you suspect that rats are entering your garden through gaps or holes in your fence, you can discourage their entry by planting this species right in front of the openings. You can throw in other spiny plants for good measure!
6) Daffodils (Narcissus spp.)
While daffodils appeal to us due to their delicate and bright spring blooms, rodents dislike them due to their strong fragrance. The scent is produced by a combination of terpenoids, which help promote pollination by attracting a wide range of insects. The bulbs themselves are poisonous to many small, warm-blooded animals, including mice, squirrels, and voles.
Daffodil bulbs can be planted around beds with species that are highly susceptible to browsing mammals. Though they may not be very effective outside of spring, when the blooms are absent and the leaves die back, their bulbs should still help prevent mice from creating burrows. For maximum effect as a repellent above ground, the fragrant blooms need to be present.
Another downside to using only daffodils as a pest-repellent is their bulbs will need to be dug up and the ground will need to be tilled on a yearly basis. Keep in mind that these are generally treated as annual plants, and thus they may require more effort to consistently cultivate (as opposed to perennials).
7) Black pepper (Piper nigrum)
Chiefly grown to produce its flavorful peppercorns, P. nigrum is a tropical plant with global popularity. It seems to have been around as a farmed herb for ages as its culinary use dates back to 2000 BCE. Once an extremely valuable spice that could be creatively utilized as currency or ransom, black pepper is currently perceived as a staple seasoning, traditional medicine, pest repellent, and strong fragrance.
As mice and rats instinctively rely on their sense of smell to determine which plants are safe to eat and which ones may be toxic, they stay away from black pepper. They are wise to avoid this plant as it contains piperin, a phytochemical compound that gives the peppercorns their unique taste and potency. Piperin is toxic to rats and naturally causes nasal irritation.
To increase the effectiveness of black pepper as a rat repellent, collect its peppercorns and grind them. Combine the particles with cayenne pepper, which contains capsaicin. The combined effects of piperin and capsaicin should temporarily deter most types of vermin. The fragrance from the essential oils of black pepper should also help keep them away from key openings around your home.
8) Peppermint (Mentha x piperita)
Peppermint is a hybrid between M. aquatica and M. spicata, both flowering plants that are known for their strong scent profiles. Now cultivated around the globe as an ornamental and culinary herb, it is a rapidly-growing perennial with the capacity to spread quickly. When intact, the leaves emit a faint minty scent. Crumpling them in one’s hands and chopping up the leaves release more of their essential oils, which have pesticidal properties.
Pulegone and menthone, the scent-producing phytochemicals in peppermint oil, are commonly used to deter rodents. The oil is lauded as an eco-friendly and cheap deterrent. Moreover, it is an ethical option as it does not necessarily kill rodents. If you have dense stands of peppermint outdoors, you may opt to collect the leaves and place them in areas that you suspect are frequented by rodents. You may also purchase the extracted oil, mix in some water, and use it as a repellent spray.
Unfortunately, the actual herb, when planted outdoors, does not necessarily keep rats away. These rodents may even run around dense stands and fertilize their roots with their droppings! For the plant to be effective, the oils need to be released.
9) Bergamot (Citrus bergamia)
Bergamot essential oil, one of the most commonly used fragrance oils in the perfume industry, is extracted from the bergamot orange. Another type of bergamot oil, derived from a type of water mint, is also used as a more modern and skin-friendly alternative to the former. Research has revealed that C. bergamia contains compounds that are photocarcinogenic (meaning that they may cause adverse effects such as rashes under light exposure).
The principal components of bergamot oil include linalool, limonene, and linalyl acetate. Recent research has shown its promise in repelling house mice, which dislike the strong smell emitted by the oil. They are less likely to take up bait that is infused or sprinkled with bergamot oil compared to those with lavender or thyme essential oils. This highlights its marked effectiveness as a deterrent in cases where other herbs may fail.
As the oil is sourced directly from the fruit, plants that have yet to produce these may not be as effective at deterring rodents as those with strongly-scented leaves and toxic sap. Bitter, the juices likely have to ooze out of the fruits for rats to steer clear of the tree itself. You may experiment by distributing the fruit’s juices or oils around infested parts of the garden, but make sure to wear gloves in the process.
10) Sweet-scented geranium (Pelargonium graveolens)
P. graveolens is widely cultivated for the production of geranium oil, which emits a strong fragrance that is similar to that of roses. An evergreen shrub, it grows at a moderate pace and usually reaches a maximum height of about 4 feet (1.2 meters). Apart from the popularity of its essential oil, it is also known as a lovely ornamental plant with attractive and vividly colored blooms.
The effectiveness of geranium oil as an insect and pest-repellent against houseflies and the like has been demonstrated in published research. The fragrant oil has also unsurprisingly been shown to repel rats, particularly when used in conjunction with bergamot oil. Additionally, the plant itself is mildly toxic to dogs and cats as it can cause skin irritations and vomiting.
11) Camphor laurel (Cinnamomum camphora)
If your garden has enough free space for a full evergreen tree, you may wish to cultivate the camphor laurel as a natural rodent repellent. This useful tree produces glossy leaves that, when crushed, emit the unmistakable scent of camphor. In some countries, the oldest specimens of this species are considered sacred.
All parts of the camphor laurel, including the entirety of its wood, contain compounds that have shown promise for use as natural pesticides. Camphor itself, which is a flammable and crystalline substance, can be extracted from the entire plant. It is an important component of incense and of some strongly-scented culinary dishes. A constituent of one of this tree’s fragrant compounds, cineole, is also used in the production of counterfeit eucalyptus oil.
Camphor can repel mice and rats because of its strong scent and its unfavorable effects upon ingestion. Symptoms of camphor poisoning generally include nausea, diarrhea, and skin irritation, even in larger animals. If you’re aware, even prior to designing your garden, that your property is frequently visited by troublesome rodents, you may wish to set aside a special place for this tree. Note, however, that it does have the tendency to compete with native plants when grown in optimal conditions.