Children who absorb high amounts of DEET through insect repellents have developed seizures, slurred speech, hypotension and bradycardia.

There are new DEET-free mosquito repellents on the market today which offer some relief to those venturing outdoors in mosquito season. But there are also certain plants that are easy to grow and will have some effect in repelling mosquitoes when grown at home or safely applied to the skin.

Here are five of the most effective mosquito repelling plants which are easy to grow in most regions of the US.

1. Citronella

Citronella is the most common natural ingredient used in formulating mosquito repellents. The distinctive citronella aroma is a strong smell that masks other attractants to mosquitoes, making it harder for them to find you. Although citronella is used in many forms, such as scented candles, torches and citronella ‘scented’ plants, the living plant is more effective because it has a stronger smell.

Citronella is a perennial ‘clumping’ grass that grows to a height of 5 – 6 feet. It can be grown directly in the ground in climate zones where frost does not occur. If grown in the garden or near the patio, it should be planted in the ‘background’, behind small decorative flowers and shrubs. In northern climate zones, citronella can be grown in a large pot or planter, ideally with casters, so it can be rolled indoors during winter.

Gardening centers usually sell citronella as small plants in pots, ready to transplant to a larger pot or into raised garden beds on the ground. Once established, new plants can be propagated in early spring by splitting large clumps into smaller sections and replanting the new ‘starts’ in pots or other areas of the garden.

Citronella plants are considered low maintenance, like most grasses, and they do best in full sun and well-drained locations. Periodic applications of nitrogen-rich fertilizers will ensure vigorous growth, but this treatment only needs to be applied once a year, preferably in early spring.

When purchasing citronella, look for the true varieties, Cybopogon nardus or Citronella winterianus. Other plants may be sold as ‘citronella scented’, but these do not have the mosquito repelling qualities of true citronella. True citronella is safe when crushed and applied to the skin, but it is most effective when applied as an oil.

2. Horsemint

Also known as Beebalm, Horsemint is an adaptable perennial plant which repels mosquitoes much the same as citronella. It gives off a strong incense-like odor which confuses mosquitoes by masking the smell of its usual hosts.

Horsemint is a fast growing, shade-tolerant and drought-resistant plant which reaches a height and width of 2 – 3 feet. It does well in dry, sandy soil and can tolerate salty conditions, which is why it is often found in coastal and beach areas. Horsemint seeds can be sown indoors in trays for later transplanting, or sown directly into the ground in late summer in colder climate zones. Midwest and Eastern growing zones are favoured for growing horsemint.

Mature horsemint plants can be divided in spring and fall by dividing into small sections and transplanting into permanent locations. Horsemint can also be planted in pots for moving indoors in cold climate zones.

Horsemint leaves can be dried and used to make herbal tea. Its flowers will also attract bees and butterflies to your garden.

3. Marigolds

Commonly grown as ornamental border plants, marigolds are hardy annual plants which have a distinctive smell which mosquitoes, and some gardeners, find particularly offensive. Marigolds contain Pyrethrum, a compound used in many insect repellents.

Marigolds prefer full sunlight and reasonably fertile soil. Although marigolds can be planted from seed, starter plants are inexpensive and readily available at most garden centers. Although an annual, marigold will often reseed itself in favourable conditions, or the gardener can easily collect seeds for future germination. Established plants will need to be thinned, and flowers should be dead-headed to promote additional blooms.

Potted marigolds can be positioned near entrances to your home and any common mosquito entry points, such as open windows. The smell may deter mosquitoes from going past this barrier. While marigolds can be used as border plants around the patio, we do not advise putting marigolds on the patio table since the bright blooms may attract wasps.

Besides repelling mosquitoes, marigolds repel insects which prey on tomato plants, so you may want to plant a few marigolds in your tomato bed for added protection.

4. Ageratum

Also known as Flossflowers, Ageratum emits a smell which mosquitos find particularly offensive. Ageratum secretes coumarin, which is widely used in commercial mosquito repellents.

Ageratum is a low-lying annual ornamental plant which reaches heights of 8 – 18”, and is easily recognized by its blue flowers, although there are varieties with pink, white and violet blooms. This plant will thrive in full or partial sun and does not require rich soil. It is often displayed in rock gardens where low-lying plants are favoured.

Although the leaves of Ageratum can be crushed to increase the emitted odor, it is not advisable to rub the crushed leaves directly on the skin.

5. Catnip

Catnip is a natural mosquito repellent. In August 2010, entomologists at Iowa State University reported to the American Chemical Society that catnip is ten times more effective than DEET, the chemical found in most commercial insect repellents. According to Iowa State researcher Chris Peterson, the reason for its effectiveness is still unknown. “It might simply be acting as an irritant or they don’t like the smell. But nobody really knows why insect repellents work.”

In the laboratory, Peterson put groups of 20 mosquitoes in a two-foot glass tube, half of which was treated with nepetalactone, a biologically active characteristic constituent of catnip. After 10 minutes, only an average of 20 percent – about four mosquitoes – remained on the side of the tube treated with a high dose (1.0%) of the oil.

In the low dose test (0.1%) an average of 25% – five mosquitoes – stayed on the treated side. When the same tests were conducted using DEET (diethyl-meta-toluamide), approximately 40 to 45% – eight to nine mosquitoes – remained on the treated side. A ten-fold higher concentration of DEET was required to obtain results similar to those of the Catnip.

Catnip, Nepeta cateria, is very easy to grow. This perennial herb is related to mint, and grows readily both as a weed and a commercially cultivated plant in most areas of the US.

While catnip will repel mosquitoes in close proximity to the plant, some people apply crushed catnip leaves or catnip oil for more robust protection. Bear in mind, however, that cats will respond to you similarly as they would respond to the plant itself. Cat owners may want to choose an alternative plant for repelling mosquitoes.

MOSQUITO CONTROL PLANTS: CARNIVOROUS

Pitcher Plant

The pitcher plant, also known as trumpet leaf, doesn’t repel mosquitoes; it attracts and eats them and uses them as nutrients to grow. It’s often grown as a curiosity plant because of its insectivorous nature. Pitcher plants are often grown in baskets you hang near your porch or patio and in plant stands you can set out on your deck or patio. The flowers are green with purpled- veined hooded pitchers, growing up to 4 feet long. They grow well in sun to light shade. They like wet soil, and do well in damp spots and bog gardens. Choose an area where they will get plenty of moisture, or just grow them in baskets and hang them near you outdoors. Other carnivorous plants you can grow to repel mosquitoes include:

• Drosera, which attracts insects with its scent and uses an acid to dissolve them once they land on its flowers.
• Venus flytraps, which eat many types of insects, including mosquitoes. They only eat a few insects week, and they are tropical plants.

You can grow carnivorous plants indoors as houseplants to catch a mosquito that makes its way indoors.

HERBS THAT REPEL MOSQUITOES

Many herbs have dual purposes. You can use them to spice up your meals, treat ailments and even as a way to keep mosquitoes away. Let’s look at the best natural mosquito repellents among these plants.

Rosemary

Rosemary not only adds flavor to your favorite roasted meats, it’s also a natural mosquito repellent plant. You can grow rosemary as a perennial, evergreen shrub for borders, hedgerows, and even creeping varieties in hanging baskets. Rosemary’s small, pale-blue flowers and spiky leaves complement your garden and make it an interesting plant. You can grow rosemary as a perennial in USDA plant hardiness zones 8 through 10 and as an annual in other areas. It needs full sun and well-drained soil.

Mint

Mint’s sweet smell is pleasing to humans but not to mosquitoes. These spreading perennials are grown for culinary use and as ornamental plants for their variegated leaf forms. They produce tiny pink, white or purple spiky flowers and grow up to 36 inches high. Mint is hardiest in USDA plant zones 8 through 10 and can become invasive, so be careful where you plant them. They need full sun to part shade and bloom in summer.

Basil

Another spice with a dual purpose, basil not only tastes great in your favorite dishes but it also gives off a strong scent that repels mosquitoes. It’s a bushy annual you can grow in a flowerbed near a patio, porch or other outdoor sitting areas. Basil’s lovely green leaves balance well with colored flowers. You can also grow basil in containers and place them near you when you’re outdoors. Basil grows in moist, well-drained soil and full sun, and because it’s annual, it grows in all regions.

Lavender

Lavender gives off a scent that is calming to humans but repels mosquitoes and other pests. It is a hardy perennial often grown as an annual. Lavender looks great when grown as a border and in containers. The plant’s tiny tubular flowers in shades of blue or purple are a perfect addition to your flower beds or as a container plan to add color to and a nice fragrance to your patio or deck. Lavender is hardy in USDA plant hardiness zones 5 through 10, but you can grow it in other regions as an annual. It needs full sun and ordinary soil and blooms in late spring through summer. Other mosquito-repelling herbs you can add to your garden include:

• Lemon balm
• Lemon thyme
• Garlic
• Clove
• Lemon grass

Plants alone can’t protect your entire yard from these pests, but they can help keep mosquitoes away in small areas where the plants are located. To protect your entire yard, you need to use a combination approach that includes plants and other safe mosquito repellants. Let’s look at other options for how to repel mosquitoes less naturally.

MOSQUITO MISTING STATIONS

Mosquito misting stations work by using a time-released sprayer to release a fine mist of an insecticide to kill mosquitoes. These systems include spray nozzles you can mount on fencing or poles around the perimeter of your home.

While misting systems work to control mosquitoes, they have some disadvantages:

• The insecticide used also kills beneficial insects, such as honeybees, butterflies, and lady bugs.
• People and pets can be exposed to the insecticides.
• One of the common insecticides used, permethrin, is toxic to fish.
• Using these systems can lead to insecticide-resistant mosquitoes.

The Environmental Protection Agency (EPA) recommends Integrated Pest Management (IPM), which includes using a variety of pest management solutions in and around the home. For mosquito control, this would include:

• Getting rid of standing water to prevent breeding and kill larvae
• Using plants in your garden or on patios that repel mosquitoes
• Using mosquito-repellant sprays or lotions that contain DEET to prevent mosquito bites

If you want a safe, all-natural approach to mosquito control, IPM is the best solution. This way you can use a variety of safe mosquito control methods to repel or kill mosquito without harming your family, pets, beneficial insects, other wildlife or the environment. There are a variety of safe options for controlling mosquitoes. One of those is the mosquito trap.

MOSQUITO TRAPS

Mosquito Magnet® Traps are safe alternatives to misting systems. They do not emit potentially harmful insecticides. They protect a large outdoor area of up to an acre.

Mosquito traps are a long-term solution and are scientifically proven to be safe and effective for controlling mosquitoes. Mosquito Magnet® offers a choice of different models:

• Executive
• Patriot Plus

Let’s take a look at how they work. 

1. Traps convert propane to CO2 that is mixed with a precise level of heat, moisture and a secondary attractant.
2. When mosquitoes are drawn to the trap, a vacuum sucks them in a net.
3. Once in the net, the mosquitoes are trapped. They dehydrate and die within 24 hours.
4. Every 21 days you change the propane tank and net

Mosquito traps begin to work immediately, but it can take up to 4 weeks to break the mosquito breeding cycle. Plan to set the trap up and get it working in spring. Mosquitoes become active once the outdoor temperature warms to 50°F, so you want your trap up and running before temperatures warm to protect your entire yard all season long.

While the plants mentioned in this article have been shown to have mosquito-repelling properties, there are environmental variables that can mitigate their effectiveness. A breeze may direct odors in the opposite direction if advancing mosquitoes, reducing the plant’s effectiveness. New formulations of non-toxic mosquito repellents are commercially available and are advised for people who want to enjoy the outdoors without the annoyance of persistent mosquitoes.