Able to form highly sophisticated colonies, termites can be extremely troublesome in the home and garden. Members of the infraorder Isoptera, these insects are known for their capacity to eat through large amounts of wood. Well-established colonies can destroy entire structures and hollow out massive trees. Remarkably successful as ecosystem engineers, they are found in all continents except for Antarctica.
In the wild, termites play important roles because of their ability to form extensive tunnels in bottom substrates. They can break down significant amounts of detritus, freeing up nutrients for plants and microbes. It’s highly likely that any ecologically balanced garden will have its own small population of termites. Their presence shouldn’t be all too alarming if you have woodpiles or wooden fences, but you should be concerned if you begin to notice signs of swarms close to your home.
Termite colonies can create tunnels that are as much as 20 feet (6 meters) deep in the ground, especially in areas that receive ample moisture. As temperatures warm, they may begin to swarm toward the surface and close to the base of trees or other wooden structures. Massive colonies usually need to be controlled using chemical means, especially in the absence of their natural predators. Interestingly, some plants can minimize the chances of infestations as well!
1) Mint (Mentha spp.)
Mint generally favors moist and rich substrates, which are conditions that are linked to the habitat preferences of many termites. These strongly-scented plants are often the perfect natural barriers for a wide assortment of pests. Their capacity to spread quickly and form extensive, low-maintenance stands proves their phenomenal worth in the garden. As a bonus, they produce inflorescences that attract beneficial pollinators.
Rich in insecticidal and highly aromatic phytochemicals like menthol, pulegone, 1.8-cineole, and limonene, the essential oils of various mint species can function as an environment-friendly means of pest control. Released when the leaves or shoots are damaged, the scent of the oils can quickly waft through the garden and discourage many subterranean pests, including termites, from rising to the surface.
To be truly effective at repelling colonies, however, mint oils work best in their pure, extracted form. These can be incorporated into water-based sprays and distributed around places where termites or their tunnels have been detected. For good measure, you may also spray the perimeter of your home, making sure to focus on wooden structures and susceptible shrubs and trees.
2) Catnip (Nepeta cataria)
As catnip is another notable member of the Lamiaceae or mint family, it’s no wonder why it is so effective as a natural insect repellent. A well-established stand of this species can bring a wealth of benefits to the home garden. Apart from serving as a fantastic ornamental plant and attracting a wealth of pollinators, it can help prevent infestations of aphids, termites, squash bugs, and flies that are likely to damage your other plants.
Though cats seem to be obsessed with catnip, it is hardly appealing to other groups of animals. Its bitter leaves are packed with a phytochemical called nepetalactone, which can have a direct effect on the nervous systems of insects. High concentrations of catnip oil have been proven to be effective at killing termites in a laboratory setting. Outdoors, the extracted oils can be infused into the top layers of soil to deter termites from tunneling toward the surface.
Catnip oil can thus be used as a natural, subterranean barrier to prevent termites from harming your home or garden. It’s also highly unlikely that swarms will form tunnels around well-established stands of the plant. In the face of a large colony, however, catnip would not be an ideal solution. Its oil breaks down over the course of a few days to weeks, so it should only be used for preventive purposes.
3) Vetiver grass (Chrysopogon zizanioides)
Known as “khus” in its native range, vetiver grass is a tropical perennial under the Poaceae family. Characterized by clumping and erect culms, which can grow as much as 10 feet (3 meters) tall, it has a remarkable tolerance for a wide range of temperatures and moisture conditions. This hardy grass is borne on a strong root system that spreads vertically instead of horizontally. Its finely structured roots can reach a depth of 13 feet (4 meters)!
One of the most fascinating features of vetiver grass lies in the formulation of its oils. Among the oils of many plants with insect-repellent properties, that of vetiver grass has perhaps shown the most promising effects as a natural termiticide. Present in the deep roots of the plant, the essential oil contains nootkatone – a ketone that is toxic to some types of subterranean termites.
Termite colonies are unlikely to create tunnels and consume wood and its byproducts in areas that have been treated with vetiver grass essential oil. The leaves of this valuable grass can be incorporated into compost, through which its oils will naturally seep. The compost can then be applied around key parts of a tree plantation or around wooden structures that are susceptible to termite damage.
4) Garlic (Allium sativum)
Set apart by its strong scent and intense flavor, garlic is an unsurprising addition to countless lists of insect-repellent plants. This phenomenal root crop is packed with compounds that, when released by damaged cloves, can repel both the mythical vampire and the tiny termite. It’s no mystery why this plant has traditionally been cultivated and strung up to protect homes.
Crushing garlic cloves induces chemical reactions that trigger the breakdown of many of its sulfur-containing compounds. These become transformed into new phytochemicals that create the “hot” sensation when raw cloves are consumed. The transformed oils are highly potent and aromatic, making them effective as a deterrent for scent-sensitive insects and grazers.
To use garlic as a natural termite repellent, you should harvest its bulbs and crush or finely grind its fresh cloves. Places the ground garlic into a container with distilled water and allow its chemicals to gradually seep out over the course of 24 hours. The infused spray can be used the following day. Make sure to target areas with moist substrates, along with logs, decaying wood, and any other parts of the garden that may attract termites. Exposed termites may die shortly upon contact with the alkaloids in garlic oil.
5) Marigolds (Tagetes spp.)
Commonly cultivated for the vibrant colors of their summer blooms, marigolds are incredibly beneficial annuals and perennials. As long as their roots are provided with ample moisture and nutrients, these delicate plants grow well in just about any type of substrate. Some of the most highly sought-after and beneficial species include the French marigold (T. patula) and the African marigold (T. erecta).
A combination of popular marigolds can be grown with the intention of repelling a wide range of pests and attracting their potential predators. As termites are sensitive to strong smells, the fragrant scent of marigold blooms and foliage can deter them from creating tunnels close to well-established stands. Some gardeners opt to grow marigolds in between or around susceptible trees and shrubs.
To protect the perimeter of your home, you may also cultivate various marigolds as border plants. However, keep in mind that, in northern temperate zones, even perennial species may only occur as annuals. As the warm season approaches, heralding the surface movements of many types of termites, you can prepare your garden by re-planting these insect-repellent ornamentals.
6) Painted daisies (Tanacetum coccineum)
Often grown for the vivid colors of their spring to summer blooms, painted daisies are a lovely addition to flower gardens and cottage borders. These herbaceous perennials grow to about 3 feet (1 meter) tall under full to partial sun exposure. Hardy to USDA zones 3 – 7, their well-established stands are low-maintenance and will seldom require pruning as they are unlikely to spread aggressively.
Apart from adding bright pops of color to the garden, this species is valuable because it is a magnet for many beneficial insects. Centipedes, praying mantises, ladybugs, and parasitoid wasps are just a handful of insects that are unable to resist their blooms. These either prey on or parasitize termites, making them less likely to form exponentially growing colonies. In this way, termites can be repelled in an indirect and environmentally sustainable manner.
Apart from attracting termite predators, painted daisies are also a source of pyrethrins. Present in the blooms, these are compounds that have strong insecticidal and pest-repellent properties. If you’re into organic gardening and appreciate the look of a wildflower garden, this is definitely the right species for you! Keep in mind, though, that the oils in its leaves are toxic to both humans and pets.
7) Geraniums (Pelargonium spp.)
Scented geraniums are able to help control termite populations in pretty much the same way that painted daisies can – in an indirect manner. Popular as ornamental garden plants because of their colorful blooms and patterned leaves, they increase diversity by attracting many beneficial insects.
Some natural termite predators, like spiders and centipedes, favor being close to stands of geraniums. Many of these will jump on the chance to attack an unsuspecting winged or non-winged termite. As more and more beneficial insects begin to congregate around your garden or within the vicinity of your home, the likelihood of termite infestations (or of any other insect pests, for that matter) in your area can be reduced.
It would be great to grow geraniums alongside many other flowering ornamentals like marigolds and catnip. When these plants are maintained properly, their repellent effects are likely to be compounded. Grow them in diverse borders around the home, particularly during the onset of the warm season, to prevent termite colonies from creeping past their root systems.
8) Lemongrass (Cymbopogon citratus)
Lemongrass is perceived as a multi-use crop throughout its native range. Its lemon-scented and citrus-flavored leaves are used to add complexity to many traditional dishes. The leaves themselves are not entirely easy to eat unless they are finely cut. They release their distinctly fragrant oils as they break down in the heat, making them perfect for oriental infusions made to treat various ailments.
Due to the aromatic phytochemicals in lemongrass essential oil, it can be used as a natural form of termite prevention. The leaves can be incorporated into compost, much like vetiver grass can, which may then be mixed into the upper layers of the substrate. Once termites come into contact with the oils, they are likely to retreat and search for other areas through which they may safely surface.
Several studies have looked into the effects of lemongrass oil on various species of termites. Some of these also examined its capacity to protect wooden structures by actively repelling these insects. Their results have so far been remarkably promising, highlighting the potential of lemongrass and its close relatives (e.g. citronella grass) as a natural means of controlling termite populations.
9) Oregano (Origanum vulgare)
Cultivated as an ornamental plant, a source of essential oils, and a culinary herb, oregano is a valuable member of the mint family (Lamiaceae). It is set apart by its light green, spade-shaped, and leathery foliage. When torn, the leaves secrete a distinctly fragrant and heady aroma. This is generated by a complex mixture of volatile phytochemicals, many of which have pesticidal properties.
Apart from directly discouraging termite infestations with their scent, oregano leaves can be used to control termites in an indirect manner. This herb’s stands can be grown as a source of nutrients for chickens, which are natural termite predators! If you’re amenable to caring for chickens in your own small farm or cottage garden, growing oregano should help keep them content whilst aiding in keeping termite populations to a minimum.
Oregano oil itself can also be incorporated into an environment-friendly and homemade termite spray. Target the base of susceptible woody plants along with any weak spots through which termites may bore around the home.
10) Lavender (Lavandula spp.)
A list of termite-repellent plants would not be complete without this final group of fragrant and flowering herbs. Lavender species, of which there are dozens distributed throughout mildly temperate climates, are known for their powerful essential oils. Packed with many pesticidal phytochemicals, these can be used to naturally repel termites and many other troublesome pests.
Lavender oil has been examined as a natural protectant of some types of wood, particularly those that appeal to termites. When applied to Norway spruce (Picea abies), for example, the oil can be almost as effective at repelling termites as commercial biocides. This highlights its potential as a safe and environment-friendly alternative to chemical-based wood protectants. Note, however, that the concentration of the lavender oil solution has to be high enough to emit a strong fragrance.
Apart from directly using lavender oils, you may plant a few stands and encourage them to bloom. Their scented inflorescences attract beneficial insects, like dragonflies, which will readily prey on termites. You can occasionally collect cuttings to release the scent of the plant’s oils. Distribute the fresh cuttings around parts of the home or garden that are frequented by pests.
