9 Garden Plants That Repel Slugs 2022
It’s all too easy to become dismayed by the havoc wrought by tiny pests in the garden. Despite their small size, they are able to chew away at and seemingly suck the life out of plants. Once they find delectable greens, they may begin to spread like wildfire as they grow into their mature sizes and reproduce. With their insatiable appetites and tendency to feed at night, slugs are some of the most troublesome of these pests.
Able to eat twice their body weight in the span of a single day, slugs can be quite destructive in their microhabitats. They have the capacity to consume a wide variety of food sources and are thus actually highly valuable as decomposers. However, this ecological role can easily be overlooked in the garden, where they may inadvertently feed on precious plants. Young delphiniums, dahlias, hostas, and many vegetables may all succumb to the appetite of a few slugs even before coming into bloom.
Fortunately, there are a few natural ways of deterring troublesome slugs. First, keep in mind that their preference for moist and dark areas of the garden encourages them to proliferate in areas with debris. Keeping your garden tidy, clean, and free of weeds is the first step to controlling their population. Planting fragrant herbs and roughly textured plants around delicate species should then help keep them away.
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1) Lamb’s ears (Stachys byzantina)
Highly textured due to the fuzzy hairs on its leaf surfaces, lamb’s ears are all too appropriately named. This seemingly delicate perennial is an evergreen herb of the Lamiaceae or mint family. It produces essential oils that give it a striking aroma whenever the internal tissues of the leaves or stems are exposed. It comes in many greenhouse cultivars, such as ‘Big Ears’ and ‘Helene Von Stein’. These are known for their large leaves, which may grow as long as a foot.
S. byzantina is particularly effective against slugs. These pests not only dislike the plant’s foliar texture but also have an aversion to its aroma. Even its inflorescences are densely covered in hairs, protecting the blooms from creepy crawlies that may attempt to scale over the stems and branches. In flower from late spring to early summer, this perennial can attract many pollinators and bring muted colors to the garden.
Lamb’s ears are hardy to USDA zones 4 – 10. In areas with mild winter conditions, its leaves are able to last through the season. Low-maintenance and easy to grow, it is perfect as a ground cover or border plant in fully sunlit or partly shaded areas. It can also be used as a lovely accent to the rough textures of rock gardens and rose plantings.
2) Lavender (Lavandula spp.)
With almost 50 taxonomically accepted members of the Lavandula genus, one can create a diverse lavender garden to keep virtually all types of pests and grazers away. Though this aromatic plant is incredibly alluring to us, so much so that its essential oils are highly valued, many animals absolutely detest it. The oils are rich in phytochemicals, with linalyl acetate and linalool taking up most of their contents.
The most popular types of lavender are L. angustifolia, L. dentata, L. stoechas, and L. x intermedia. These species are grown in many dedicated farms in Europe and Asia, where the oils are industrially extracted and used for a wide range of products. Many hybrids are grown as ornamentals, in pots, containers, or as border plants, in gardens with relatively dry conditions. Full sun coupled with superior soil drainage is essential to good growth.
Hardy to USDA zone 5, most lavender species are suited to temperate zones with moderately cool winter conditions. If your area experiences considerable rainfall, it may be necessary to look into the specific tolerances of each species as some are more likely to persist in moist conditions than others. Healthy lavenders should ideally be planted alongside other species with a preference for dry substrates.
3) Wormwood (Artemisia absinthium)
Known for being an ingredient in the infamous alcoholic spirit, absinthe, wormwood is a culturally and pharmacologically important plant. It is now naturalized in the US and Canada, where wild stands tend to grow in arid and uncultivated areas. It has a preference for fertile, nitrogen-rich substrates that receive ample sun exposure. Unfortunately, it does not do particularly well as a companion plant and should be raised in dedicated beds.
Wormwood may not be the safest pest repellent plant if your garden is frequented by toddlers and pets. Its toxic components contain remarkably volatile phytochemicals which, in high doses, may even cause convulsions and fatalities in both humans and animals. It comes as no surprise, then, that this plant keeps the most daring of slugs away.
An herbaceous perennial, wormwood is distinguished by its silvery-green and irregularly-edged leaves. These are borne on grooved and branching stems that may grow as tall as 4 feet (1.2 meters) in optimal conditions. Tube-shaped and light-yellow flowers may appear from summer to autumn. If your pest-ridden garden also happens to be in need of muted colors, you should definitely consider cultivating this species.
4) Fennel (Foeniculum vulgare)
A popular member of the carrot family (Apiaceae) due to the use of its bulb as a culinary vegetable, fennel is a hardy and highly nutritious plant. However, its nourishment value does not extend to some types of pests, which are turned away by the scent of its oils. The scent of fennel can be described as distinctly bitter. Slugs, snails, and grazers are likely to stay away from both its exposed and buried components.
As fennel is a popular kitchen ingredient, it wouldn’t be out of place in a vegetable garden or around a patch of delicate herbs with fewer defenses against pests. Like wormwood, it also happens to be one of the primary ingredients in absinthe. Its strong taste and smell are caused by a unique combination of volatile oils. Its flavor is likened to that of anise seed and licorice, which are both known for appealing to an acquired taste.
Fennel is now agriculturally produced in countries like India, China, and Bulgaria, which make use of its bulb to flavor a wealth of fragrant dishes. A fast grower, it can easily be propagated by seed in rich substrates. The best time to introduce fennel into your garden is in spring, as soon as the final frosts have passed. Note that a healthy seedling can mature in as little as 60 days.
5) Hydrangea (Hydrangea spp.)
Known as either hydrangeas or hortensias, these flowering plants are popular ornamentals due to their bouquet-like inflorescences of pastel-colored blooms. They can make a garden look especially stunning and productive, especially at the peak of their flowering period. Stems may be so flower-heavy that they arch forward or droop in the attempt to attract as many pollinators as possible through spring and summer.
Interestingly, hydrangeas are unappealing to slugs, snails, and many other small pests and grazers. They are not wholly effective against all herbivores, though they are seldom a first choice due to their mildly toxic contents. Hydrangeas contain cyanogenic glucosides, compounds that are poisonous in considerable doses. Pets that inadvertently consume these plants may experience gastrointestinal discomfort.
Another fascinating characteristic of hydrangeas is their pH-dependent flower coloration. Species that do not have white flowers may have blooms that are anywhere on the spectrum from blue to red. If the pH is acidic (below 7), the flowers tend to have more blue tones. Conversely, if the pH is neutral to basic, the flowers tend to be pink or red.
6) Ferns (Polypodiophyta)
Though they frequently thrive in the same environmental conditions favored by slugs, ferns and these slimy pests simply do not mix. Ferns are slug-resistant plants because of the tough features of their leaves, which are simply unpalatable to many animals. The complex leaves, which may be scientifically termed “megaphylls”, are composed of multiple leaflets. These are perfectly arranged to create a highly textured, yet ordered appearance.
If the moist and partly shaded areas of your garden are frequented by slugs, try cultivating a dense stand of ferns. These may disinterest the slugs, eventually forcing them to seek food elsewhere. Another great thing about ferns is that many grazers dislike their leaves. They can be grown around other shade-loving plants with highly susceptible features.
To create an attractive fern and slug-repellent garden, make sure to select species that are suited to the conditions of your area. Some ferns only do well in high humidity and moist conditions, whereas others thrive better in higher elevations with ample ventilation. Some of the most popular types are grouped into maidenhair ferns, royal ferns, staghorn ferns, and tree ferns.
7) Euphorbia (Euphorbia spp.)
With over 2,000 species in their genus, euphorbias belong to a highly diverse set of desert-loving plants. They are known for being physically tough and relatively hardy in the face of various climatic conditions. Often mistaken as cacti due to their spikes, hardened exteriors, and growth forms, euphorbias have evolved to be heat-tolerant flowering perennials.
Able to thrive as houseplants and as outdoor ornamentals, euphorbias favor poor soil conditions and can withstand brief droughts. All varieties are usually highly unpalatable to slugs and many other pests due to their sap. Describable as a milky type of latex, the sap is bitter, potentially irritable, and may even be poisonous in some species. The composition of the sap is suspected to have evolved as a deterrent to grazers.
When handling fully grown euphorbia plants and cuttings, it is advisable to wear gloves and eye protection. Skin contact with the irritant sap may cause dermatitis and markedly painful inflammation. This is due to the presence of diterpenes and triterpenes, chemical compounds that are associated with caustic effects. It’s no wonder why euphorbias often look pristine and wholly intact in areas where herbivores and pests may attack neighboring plants.
8) Japanese anemone (Eriocapitella hupehensis)
Known for being delicate yet highly resistant in the face of pests, the Japanese anemone is a lovely flowering plant. It may be difficult to grow in gardens due to its shallow and easily damaged root system. However, once it is established, it can begin to spread like wildfire to form a natural boundary against slugs and snails. Its main method of proliferation is via underground rhizomes.
You may opt to plant this species as a type of ground cover or as a border plant around flower beds that may be more susceptible to pests. It spreads as clumps which are distinguished by their basal leaflets, borne on petioles that extend up to 14 inches (35 cm) off of the ground. Leaves may also occur along fine stems, but these are generally smaller in comparison.
Japanese anemone blooms occur on a cyme, which is a clustered type of inflorescence. Though they may appear to have petals, their colorful structures are actually specialized sepals. The flowers are typically white, purple, pink, or a mixture of these colors. They begin to appear in summer and may last through fall, attracting a diversity of beneficial pollinators to the garden.
9) Rosemary (Salvia rosmarinus)
With its tough leaves, woody stems, and unmistakable scent, rosemary is a fantastic perennial to have in any herb or vegetable garden. This hardy plant is exactly what many pests wish to avoid as they attempt to graze through the delicate components of plants. Slugs are no match for the toughness of mature rosemary stalks, which they are likely to find unpalatable and malodorous.
For rosemary to be an effective pest repellent, it needs to be placed in key areas of the garden. These include entry points and densely planted areas, where the substrate may be cast in shadow and kept cool. It can also be planted in between stems of highly vulnerable plants, given they are each afforded ample space. This not only aids in keeping those pesky slugs away; it also ensures that you have a steady supply of rosemary leaves for your culinary creations.
In areas with mild climates, rosemary is able to persist all year round. It can even tolerate brief periods of severe dryness. This plant’s pink, deep blue, or purple flowers, which significantly soften its appearance, usually arise in spring to summer. For the best ornamental value, make sure to look for the following cultivars: ‘Severn Sea’, ‘Benenden Blue’, and ‘Miss Jessop’s Upright’.