Autumn often appears to be the season of spiders. As day lengths shorten, temperatures cool, and natural food becomes scarcer, these eight-legged creatures may venture in search of sturdier forms of shelter and sources of warmth. Those close to urbanized areas tend to creep into walled gardens and homes, anchoring their webs onto protected shrubs and concrete structures.
While spiders are generally harmless toward humans, only biting if they are truly threatened or captured, you may wish to repel them to minimize uncomfortable encounters with their kind. Perhaps one recently slipped into a garden glove or created a troublesome nest in a secluded part of the yard. Whatever your reason, fret not because there are many natural ways of repelling spiders.
Some gardeners opt to use pesticides or vinegar-based sprays, but one of the best and most environmentally-friendly means of keeping potential pests away is by growing the right plants. Many beneficial herbs and trees, especially those which produce strong odors, are generally avoided by spiders. These can be planted close to your home’s entry points. Conversely, if you wish to attract instead of repel spiders for their many benefits, you’ll want to avoid growing large stands of these plants.
1) Lavender (Lavandula spp.)
Extensively grown to meet global demand for their oils, Lavandula species are truly some of the most valuable ornamental plants. Named for the alluring pastel shade of their delicate inflorescences, they have medicinal, cosmetic, and culinary uses. The most popular of these herbaceous perennials include English lavender (L. angustifolia) and French lavender (L. dentata).
Capable of thriving well outside of their native range, lavender species favor dry, well-draining substrates like sand and loam. They produce attractive blooms when they are exposed to full sun conditions and ample ventilation. Amazingly, these plants are quite productive even in the absence of fertilizer. As long as their root systems are free of rot and pests, they can spread on their own to produce dense, fragrant stands.
Despite their aversion to high nutrient levels in the soil, lavender species are able to produce complex essential oils. Concentrated in their leaves, these oils are natural pest repellents and are most effective in their extracted forms. Though spiders typically avoid the stands of these species, some determined individuals may still come close. It may be necessary to occasionally break off leaves to expose their strong fragrance.
2) Basil (Ocimum basilicum)
Best known for its culinary uses, basil produces remarkably flavorful and fragrant leaves. Simply rubbing the leaves or crumpling them in between two fingers releases their unmistakable and overpowering scent. It’s no mystery why small insects and large grazers alike avoid the bitter leaves. Even garden spiders are likely to keep away from healthy basil stands.
The essential oils of O. basilicum and its cultivars contain volatile and potentially toxic compounds. While these are rarely harmful to humans, especially when only small doses are consumed, they can be damaging to many insects. The scent they emit serves as a clear signal of their highly potent nature. Studies that have exposed small pests to basil oil have clearly shown its potential as a natural insecticide.
Distinguished by their ovate, green, and delicate leaves, some of the most popular basil cultivars include Thai basil, purple basil, and sweet basil. The essential oil compositions of these are largely influenced by their growth conditions, with subtle key differences occurring between subpopulations of the species. Warm temperatures, regularly moistened substrates, and pest management are crucial to their productivity.
3) Rosemary (Salvia rosmarinus)
Leathery, needlelike, and deep-green leaves arising from increasingly woody stems are this perennial’s most prominent features. In spring to summer, healthy specimens produce attractive pink, lavender, or blue flowers. While these can attract many beneficial pollinators to the garden, they are unlikely to draw in troublesome insects. The plant’s mixture of phytochemicals can deter even the most courageous of spiders.
Rosemary essential oil, which is released upon mechanical or heat damage, has lethal effects when it comes into direct contact with many small insects. When the oil is applied to the surfaces of more vulnerable crops, it can act as a natural insecticide without damaging the tissues of the host plant. Of course, for intact herbs to repel spiders, they must be present in large densities and may need to be pruned occasionally to release their fragrance.
4) Mint (Mentha spp.)
Found in many environments with moist to wet substrates, Mentha is a popular genus with a sub-cosmopolitan distribution. It contains over a dozen species of strongly-scented plants, many of which have herbal, cosmetic, and culinary uses. The pungent fragrance is produced by essential oils and is released when the leaves are rubbed or more heavily damaged.
Markedly large stands are more likely to emit wafts of their minty scent. If you intend to grow these plants for their insecticidal properties, allow them to mature into a decent size. Of course, you’ll need to regularly prune the shoots or harvest the leaves to release their scent. Regular pruning will also help prevent the mint plants from spreading uncontrollably.
Some of the most common mint varieties include spearmint (Mentha spicata) and peppermint (Mentha x piperita). The essential oils of these plants have thoroughly been studied and evaluated for their natural pesticidal properties. Some of the major constituents of the oils are lethal to small insects. Larger grazers also tend to avoid mint plants as consumption of the leaves can cause toxicity symptoms.
5) Eucalyptus (Eucalyptus spp.)
Eucalyptus trees, also cultivated for their oils, produce a distinct menthol fragrance. In large quantities, their leaves may emit an overpowering scent that is strong enough to drive away the most determined of spiders. Although the extracted oils can function quite well as a pest deterrent within the home, fully intact and mature trees would work best in the garden.
Some of the most intense-smelling eucalyptus species include E. globulus (blue gum), E. radiata, E. citriodora, and E. dives. These produce commercially important oils with a plethora of herbal uses – from the improvement of sleep patterns to the treatment of inflammation and fungal infections. Of course, these plants have evolved to produce these oils as a form of protection against threats in the wild.
As eucalyptus essential oils tend to be highly potent and toxic to many animals, always review the dangers of each species if you intend to grow them in homes with pets and children. Note that even vaporized oils may have harmful effects upon inhalation.
6) Citronella grass (Cymbopogon nardus)
A close relative of lemongrass (Cymbopogon citratus), with which it shares a similar fragrance, citronella grass has grown increasingly popular as a natural pesticide. Throughout its native range, it is especially important as a source of mosquito-repellent oils. Spiders generally dislike all citrus scents, so those produced by the oils of this species are fairly effective at keeping them away.
Interestingly, the production of citronella oil is perhaps the only commercial use of this species. Unlike those of its close relatives, its leaves are highly unpalatable. Even cattle are averse to their texture and taste and are likely to browse other less abundant grasses. Throughout its native range, citronella oil can cover extensive areas of pasture and render them unfavorable to livestock.
It is evident that this aromatic herb has the tendency to become an invasive species in areas with rich substrates and full sun exposure. Able to grow to several feet tall and equally as wide, it is known for being a rapid grower in warm climates. If you’d like to use this grass to deter pests like mosquitoes and spiders, aim to restrict its spread to pots or containers.
7) Chrysanthemum (Chrysanthemum spp.)
Beloved by horticulturists all across the globe for its eye-catching spring blooms, chrysanthemums come in an endless array of stunning cultivars. As if their production of the most popular ornamental flowers wasn’t enough, their culinary and herbal uses have contributed to their cultural significance. Symbolic of both life and death, the flowers of these plants contain surprisingly potent compounds.
Some types of chrysanthemums were recently discovered to be rich in pyrethrins, which are lethal to many types of insects. The presence of these compounds likely protects the colorful flowers from being attacked by pests or consumed by grazers during the bloom period. As the fragrant blooms repel pests, they are also likely to be avoided by any pesky spiders.
To increase the effectiveness of chrysanthemum blooms against spiders, you may harvest, dry, and pulverize them. Sprinkle the dust around susceptible plants or in areas that tend to attract spiders and other pests. You can also cultivate a variety of chrysanthemums close to key entry points of the home or garden.
8) Lemon balm (Melissa officinalis)
Cultivated as an ornamental plant, as a source of fragrant oils, and as a natural attractant for bees, lemon balm is a multi-purpose perennial. This citrus-scented herb grows to just 1 meter (3 feet) tall, so it is an ideal addition to small and medium-sized gardens in areas with mild climates. Due to its minimal requirements and ease of maintenance, it has become naturalized in many temperate to tropical zones.
Lemon balm may be quite effective at repelling spiders due to the lemon-like scent of its leaves. Its extracted oils are often combined with those of lemon trees and citronella to create a more potent and fragrant product. It shares a major pest-repellent compound, citronellal, with these other plants.
On its own and when present in small stands, lemon balm is unlikely to effectively repel pests. Its leaves may need to be crushed to emit a stronger fragrance. To keep pests away, aim to grow this plant alongside other spider-repellent species or apply its extracted oils directly onto outdoor plants.
9) Common sage (Salvia officinalis)
A culinary herb with stunning ornamental varieties, the common sage is a truly remarkable plant. A close inspection of its tender leaves reveals that they are densely covered in fine hairs. While this gives them a fuzzy appearance, it also helps protect the plant from many pests and grazers. Coupled with the bitter taste and strong scent of the leaves, the hairs force any pesky visitors to think twice.
Able to thrive in fairly dry, well-draining, and poor substrates, sage is an ideal plant to grow in sandy or loamy gardens. The oblong-shaped leaves of this species’ type specimens are generally grey-green in color. Compared to the upper surfaces of the leaves, the undersides may appear almost totally white as they are completely covered in hairs.
Long believed to have protective properties against evil spirits and bad energy, the common sage may just be the form of defense that your garden needs. If you’re in need of an even more fragrant type of sage, consider cultivating its close cousin – Cleveland sage (S. clevelandii). This species produces a remarkably powerful, musk-like odor.
10) Dill (Anethum graveolens)
Known for its intense flavor and slightly spicy aroma, dill is a wonderful herb to plant in pest-repellent gardens. Its fine, threadlike leaves are packed with its strongly-scented oils, so just a few sprigs of them are enough to significantly alter the flavor of creams and soups. It is thus easy to imagine how repulsive its smell can be to an unsuspecting bug. Spiders are likely to steer clear of any shoots with seeping sap.
An annual herb, dill can quickly grow to a height of about 3 – 5 feet (1 – 1.5 meters). The production of its aromatic fronds is hastened in areas with rich substrates and full sun exposure. Though it does not require supplementary nutrients to thrive, its soil must be kept moist to prevent the roots from dying back. Note that, to maintain a constant supply of this plant, it must be reseeded frequently.
Dill is a suitable companion plant for vegetables like lettuce, onion, and tomatoes. When a natural low wall is created with this species, its scent should help prevent pests from attacking the vegetables. Note, however, that dense stands may also attract beneficial insects that may, in turn, attract predatory spiders.
11) Catnip (Nepeta cataria)
Also referred to as catmint or catwort, catnip is a fragrant perennial herb. Known for its fascinating effects on feline behavior, this modest plant is cultivated for both ornamental and commercial uses. It is the perfect addition to deer-resistant gardens located in areas experiencing periodic droughts. Apart from repelling grazing mammals and troublesome insects, it may also help keep spiders away.
The primary pesticidal component of catnip is nepetalactone, a terpenoid in its essential oil. When it comes to repelling mosquitoes and pests, this compound looks to be as effective as industrial-strength repellents like DEET. The mechanism by which it works has only recently been discovered. It triggers pain receptors in the nervous systems of insects, forcing them to steer clear of the fragrant catnip leaves.
Fortunately, the unpleasant effects of this compound don’t extend to us humans. We can safely make use of catnip essential oil. Either the plant or its oil can be placed in key points of the garden or home to reduce the chances of any spider or bug infestations.
12) Chives (Allium schoenoprasum)
Used as a flavoring ingredient and colorful garnish in many parts of the world, this bulb-forming plant is distinguished by its hollow, grass-like leaves. Damaging or slicing up the leaves exposes a scent that is similar to that of onion and garlic, which are its close cousins. Though the oils of Allium species may be appetizing to humans, they are undoubtedly repellent to most insects.
Arachnids tend to stay away from chives as they are unlikely to find prey around this plant. Keep in mind that spiders build their webs in areas where smaller insects are abundant. Thus, plants that repel flies, mosquitoes, and the like should be unattractive to insect predators. Moreover, the mere smell of chives might naturally drive any sensitive spiders away.
Apart from performing its services as a natural pest-repellent and fungicide, chives are also a fantastic herb to grow in your own garden as they take up minimal space, require little in terms of care, and should regularly provide you with leaves to use in your own kitchen! Grow its bulbs close to more susceptible vegetables to help keep them pest-free.
