The Best Plants That Repel Cutworms 2022 [Updated]
“Cutworm” refers to the larvae of certain moth species, most of which are in the family Noctuidae. As such, cutworms are caterpillars — not actually worms at all. The name refers to their destructive habit of cutting down seedlings and young plants at or below the soil surface, though some can climb and thereby defoliate larger plants.
Most cutworms are less than 2 inches long, ranging in color from light gray to brown or green, often with longitudinal stripes. When exposed, cutworms curl into a characteristic tight ball. These caterpillars typically hide in the soil during the day, then emerge at night to feed as a strategy to avoid predators.
Many species are major agricultural and garden pests. For example, the variegated cutworm (Peridroma saucia) is considered one of the most harmful vegetable pests in the world. A single black cutworm (Agrotis ipsilon) larva is capable of destroying an average of 5 corn plants before pupating, meaning high-density infestations can cause huge amounts of damage to corn and a variety of other crops, including alfalfa and cotton. Army cutworms (Euxoa auxiliaris), common in the western United States, are highly destructive to rangeland grasses as well as native shrubs such as sagebrush.
However, some cutworms do play an important role in the ecosystem. In their adult form, army cutworms are referred to as “miller moths”, and provide a key source of calories and fat for grizzly bears in Yellowstone National Park while also luring the bears into higher elevation areas away from places with more human activity.
How to Prevent Cutworm Infestations
Due to their destructive nature, many gardeners seek holistic solutions to avoid cutworm infestations in the first place. Some of these measures include controlling weeds to reduce available food for cutworms, tilling the soil to expose cutworms to the elements, applying mulch or eggshells to block cutworm movements, or using “collars” to protect the vulnerable areas of young plants.
Additionally, attracting cutworms’ natural enemies, including birds, beetles, spiders, and parasitic wasps, can help reduce cutworm damage. Similarly, many species of bats consume moths — the adult form of cutworms — thereby interrupting the cutworm life cycle by reducing the number of eggs being laid in the first place.
Other effective solutions involve incorporating plants that repel cutworms into a garden, with several strategies demonstrating varying degrees of success. The following list describes 8 common plants that can be used to repel cutworms and thereby prevent the damages they cause. The list is divided into types of plants that repel cutworms by direct placement in a garden, and other plants where certain parts must be used or prepared for use as a physical barrier or chemical repellent.
Garden Plants That Repel Cutworms
1) Tansy (Tanacetum vulgare)
- Family: Asteraceae
- Other names: Common tansy, cow bitter, golden buttons
Tansy is a perennial, herbaceous flowering plant with small yellow flowers and fern-like compound leaves. Native to Europe and Asia, it has a long history of medicinal uses, including treatment of rheumatism, intestinal worms, digestive problems, fevers, and measles, although in higher doses it can be toxic to humans (and to certain livestock such as cattle). Tansy has long been cultivated for these medicinal purposes and has also been used as a culinary ingredient, insect repellent, and embalming agent.
Compounds in tansy, such as thujone and eucalyptol, are toxic to insects and aid in its repellent ability. Wreaths, bouquets, sprigs, or oil extractions of tansy have historically been used to deter insects such as flies, ants, and ticks. In gardens, it is commonly a companion plant of squash, cucumbers, roses, and berries, with evidence suggesting it can repel Colorado potato beetles as well as other pesky insects such as Japanese beetles, squash bugs, and of course, cutworms.
Tansy grows best in full sun but can tolerate partial shade. It can be easily started from a purchased plant, or seeds can be germinated by directly sowing into the soil after the danger of frost has passed. Once established, tansy requires little attention and is both drought-resistant and winter-hardy. However, its easy-to-grow nature and aggressive reseeding potential mean that it is considered an invasive plant in North America, and the sale or growth of tansy is prohibited in states such as Colorado, Wyoming, Montana, Minnesota, and parts of Washington state.
2) Dalmatian chrysanthemum (Chrysanthemum cinerariifolium)
- Family: Asteraceae
- Other names: Pyrethrum daisy, pyrethrum
A close relative of tansy formerly placed in the same genus, the flower of the Dalmatian chrysanthemum resembles a common daisy, with white petals surrounding a yellow center. The fern-like leaves are blue- or silvery-green. Considered one of the most deadly flowers to insects, it is economically important as a natural source of pyrethrins, which are neurotoxic to insects and prevent female mosquitoes from biting. Pyrethrins are concentrated in the seed cases and tend to be more potent in plants that are grown at higher elevations.
Although pyrethrins are considered among the safest insecticides to use around food, contact may cause skin irritation in humans and the compounds can be toxic to other animals such as cats. The plant itself — especially its dried flowers — may also cause severe allergic reactions in some people. As companion plants, the effects of the compounds present in Dalmatian chrysanthemum are less intense.
However, because the flowers are beautiful and easy to grow, they are commonly used and have some insecticidal and repellent features to protect other plants against garden pests such as aphids, spider mites, ticks, nematodes, and cutworms. Flowers can also be picked, dried, and ground into a fine powder and spread around plants to reduce pest activity, which may be especially effective against cutworms.
Dalmatian chrysanthemums can be grown from seed, split plants, or commercially available seedlings, best planted in the spring in an open, sunny location. They thrive in temperate to cool temperate climates but can tolerate occasional heat or dry soil. Weekly watering will suffice to support the plant, though soil should be well-draining, and overwatering should be avoided to prevent root rot.
3) Sage (Salvia officinalis)
- Family: Lamiaceae
- Other names: Common sage, true sage
Native to the Mediterranean region but cultivated worldwide, sage is prized for its many culinary, medicinal, and botanical uses. Indeed, its botanical name translates from Latin as “to be saved”. Used historically as a digestive aid, natural antiseptic and preservative, and for cognitive enhancement, today sage is more popularly used as a flavor-adding herb.
Many cultivars have been derived from sage, but typically, the plant has white, pink, or purple flowers and soft, grey-green oblong leaves covered in fine hairs called trichomes. Like all members of the mint family, the stalk of the sage plant is square with oppositely arranged leaves.
As a garden plant, sage naturally repels insects such as snails, beetle larvae, and moth larvae such as cutworms (as well as cabbage moth caterpillars). It is a popular companion plant with broccoli (and other brassicas), rosemary, tomatoes, and strawberries. Since sage is tolerant to dry conditions, it should not be planted with herbs and vegetables that require rich soil.
Other plants such as fennel, rue, wormwood, cucumbers, and onions can interfere with the growth of sage (or vice versa), and as such, these pairings should be avoided. Sage thrives in well-draining soil in full sun and is most easily started from a cutting, seedling, or small plant, although seeds can also be germinated indoors. It is hardy in many climates and can also be grown in containers or indoors.
4) Thyme (Thymus spp.)
- Family: Lamiaceae
- Other names: Many, depending on the cultivar
One of the most popular culinary, medicinal, and ornamental plants worldwide, thyme is originally native to southern Europe and the Mediterranean. A common component of spice blends such as bouquet garni, herbes de Provence, and za’atar, thyme can be used as either a dried or fresh seasoning. Historically, its many uses included promoting courage, warding off nightmares, treating abscesses, and alleviating respiratory symptoms. Thyme essential oil includes high concentrations of thymol, a natural antiseptic, as well as other compounds such as linalool (which is used in the manufacturing of soaps, fragrances, and insecticides).
A bushy, evergreen shrub with small grey-green leaves and purple or pink flowers, thyme is an attractive addition to many gardens. Many types of thyme, including lemon thyme (T. citriodorus), are unattractive to nuisance insects while also attracting beneficial insects like butterflies, bees, and natural enemies of pests. Thyme varieties such as creeping thyme (T. serpyllum) can specifically attract beneficial insects like ground beetles, which naturally predate upon cutworms.
Thyme can be grown in full sun, either in containers or planted in the ground. It can be challenging to grow from seed, so propagation by cutting or layering is more popular. Thyme is drought-tolerant, but typically requires warm temperatures and can enter a dormant state in the winter. Companion plants include strawberries, tomatoes, and brassicas.
Plants That Repel Cutworms via Other Uses
1) Bamboo (Bambusa vulgaris)
- Family: Poaceae
- Method: Skewers as a physical barrier
There are many species of bamboo in the subfamily of grasses, Bambusoideae. Common bamboo, true to its name, is one of the most common and easily recognizable. It forms moderate to loose clumps and is yellow-green in color with green stripes and dark green leaves. Widely used as an ornamental plant, it can be planted as a fence or border hedge, and when dried can also be used for construction or flexible packaging.
For uses as a pest repellent, skewers made from bamboo can be used as a physical barrier. By placing two skewers on the sides of the plant, or by placing skewers in a ring of stakes around the plant, cutworms are prevented from curling all the way around a plant and thus cannot chew through plant stems. While other items such as nails or toothpicks can also be used, bamboo food skewers are typically longer and therefore can provide more effective or stable protection as a physical barrier.
2) Corn (Zea mays)
- Family: Poaceae
- Other names: Maize
- Method: Cornmeal as a lethal bait
Corn is a cereal grain in the grass family, which was first domesticated over 10,000 years ago. A staple food in much of the world, the corn plant is known for its fast-growing, tall stalks with long, wavy leaves. The edible “ears” of the corn, which are typically yellow-golden in color but can vary substantially depending on variety, are developed from the female part of the flower. Each kernel contains a seed, and these kernels can be cooked and eaten directly or ground into various forms.
Made from dried corn, cornmeal has many purposes ranging from use as flour to keeping pizza crust from sticking to a pan. Cornmeal is also highly effective when used in the garden, and can be used as a weed killer as well as for pest control. When sprinkled in a circle around seedlings or small plants at risk of cutworm damage, cornmeal can have a protective effect. Some cutworm species will voraciously consume cornmeal, which they cannot digest — so they will ultimately die from consuming it while the cornmeal remains harmless to the plants themselves. Similar concoctions of wheat bran combined with sawdust and water may also work via similar mechanisms.
3) Peppers (Capsicum spp.)
- Family: Solanaceae
- Method: Capsaicin extract used as a deterrent spray
The genus Capsicum includes common food plants such as bell peppers as well as spicier varieties of chili peppers like jalapeño, habanero, and cayenne. The active component of chili peppers is called capsaicin — a chemical irritant for many mammals, including humans — which causes a burning sensation via interaction with sensory neurons.
Though pepper plants can be victims of cutworms, when capsaicin is extracted from the fruits of the plants (the peppers themselves), it can be used as a deterrent to many common garden pests including cutworms as well as aphids, thrips, and mites. Capsaicin is included as an ingredient in many commercially available household and garden insect repellents. Homemade formulas can also be easily made by blending hot peppers and water, straining the liquid, and applying directly to the plant or around the plant with a spray bottle. Some gardeners add small amounts of dish soap or vegetable oil to increase adherence, or, simply sprinkle capsaicin-containing materials such as red pepper flakes around the base of a vulnerable stem to deter cutworms and other ground-dwelling insects specifically.
Though ingredients derived from peppers are generally earth-friendly, they can potentially be damaging to some beneficial insects and can irritate the skin or eyes, so should still be used with caution.
4) Wild chamomile (Matricaria discoidea)
- Family: Asteraceae
- Other names: Pineapple weed, rayless mayweed, disc mayweed
- Method: Tea used as a deterrent spray
The name wild chamomile, as well as its other common name “pineapple weed”, refers to the chamomile and pineapple mixed aroma that exudes from the flowers when crushed. Naturalized throughout much of North America, pineapple weed is commonly found in fields and gardens, and is edible as part of salads or teas. It is known for its medicinal uses, which include treating upset stomachs, sores, and fevers.
A close relative of German chamomile (M. chamomilla), its yellow flowerhead is similar in appearance but without the white ray florets and with a more pronounced conical shape. Wild chamomile grows well nearly anywhere: on roadsides, along footpaths, on stony slopes, and anywhere with poor or compacted soil. It does not require much care, and as such, is more frequently foraged for rather than grown.
While flower buds can be used for a tea similar to traditional chamomile, the remaining stems and leaves can also be repurposed as a cutworm repellent. After boiling the plant material in water and cooling it, this “tea” can be strained, combined with dish soap, and applied directly to seedlings and surrounding soil.