Do Mosquito-Repelling Plants Actually Work?

Originally from The Spruce
Posted here with additions and ammendments

    Biting insects that feed on blood (such as ticks and mosquitoes) locate their targets by sensing the odors and gases given off by warm-blooded creatures. Sweat and the carbon dioxide given off by breathing are key attractors. Garden plants that have strong scents can help to camouflage the scents that these insects use to target their victims, thereby confusing the bugs and protecting us from bites.
    But it's rarely enough to simply fill your landscape with growing plants of these types and hope that mosquitoes will vanish. In most cases, you'll need a more concentrated form of the plant's scent, which can be obtained by burning or crushing the leaves to release the essential oils that produce the odor.
    Bottom line is this: Even though some research shows extracts from some of these plants can help to repel mosquitos no research is saying that planting these plants in your yard will help.

    So, add these plants to your garden if you like the look or fragrance of them, but don’t count on them to protect you or your family from bites.

= Has Bug Repelling Value - = Has Little to No Bug Repelling Value

Lavender (Lavendula spp.)
    Already a favorite of many for its gorgeous fragrance and versatility in cooking, baking, and mixology (not to mention being a favorite of pollinators), lavender scores another win for repelling mosquitos. The oil naturally created by the lavender plant is thought to potentially even inhibit mosquitos' sense of smell. While the distilled essential oil applied to your skin is even more effective, a lavender bush in your garden won't hurt your pest-fighting case at all.

Mint (mentha)
    Another plant with near unlimited uses, mint comes in a wide range of varieties to suit your preferences-and any of them will be a deterrent to mosquitos. Mint is near-impossible to kill, incredibly low maintenance, and just as good for adding to your cocktails as it is for keeping your patio pest-free. Add one to your outdoor sitting area-or start a collection of mint varieties. But be warned, if you plant them in the ground, they'll spread like wildfire, so pot planting is usually best.
    Even compared to other natural mosquito repellant options, mint and its cousins hold some of the most multifunctional use beyond simply keeping bugs at bay. For this reason, they are a worthy addition to any garden that is looking to address a localized bug infestation.
See Also: More about Mint

Rosemary (Salvia Rosmarinus)
    Popular among many gardeners, this woody, fragrant herb adds an amazing touch to countless recipes and can grow massively in outdoor gardens. Its scent is a deterrent to mosquitos as well as other pesky bugs, like cabbage moths.
    Rosemary loves warm and dry climates, and may need to be moved indoors in areas with harsh, cold winters. But, all summer long it can adorn your patio and keep pests at bay. Rosemary does need full sun to prevent needle drop, but it prefers to dry out between waterings.

Clove (Syzygium aromaticum)
    When it comes to form, clove oil is clearly the way to go if you are interested in replicating these mosquito-repelling properties at home. Scientific studies up to this point have focused on clove oil alone, with promising results across the board indicating its effectiveness in the desired domain.
    Though it does carry some skin irritation risk, clove oil may be among the most worthwhile options for folks seeking a natural mosquito repellant solution.

Bee Balm (Monarda spp.)
    It might surprise you to know that this perennial plant, famous for attracting pollinating insects such as bees and butterflies, has the opposite effect on mosquitoes and other pesky insects. But that's the case with bee balm.
    Fast-growing with bright abundant blooms, this perennial does well outdoors and attracts plenty of desirable pollinators like bees and butterflies. At the same time, its fresh scent is a deterrent to mosquitos, especially if you crush some leaves between your palms. For best results, crush a few leaves to release the scented oils.

Allium (allium)
    Allium, also known as ornamental onion, are perennial bulbs that share a scent similar to table onions, garlic, and chives, which are also members of the same family. Allium is among a small handful of plants that repel mosquitoes simply by their presence in the garden. Along with repelling mosquitoes and other pests, allium plants add an exotic appeal through their unusual, globe-shaped flower clusters.

American Beautyberry (Callicarpa americana)
    The tiny white flowers of Callicarpa americana aren't much to look at, but the vibrant magenta berry clusters make this small shrub stand out in the landscape. Beautyberry plants are a member of the Lamiaceae family, which includes many mints. The fragrant oils released by crushing the leaves of the beautyberry repel mosquitoes, and the berries often last long into the winter to attract and feed songbirds and small mammals.

Catmint (Nepeta)
    Not to be confused with every cat's favorite plant, catmint is a related plant that blooms little two-lipped flowers. What makes them so good at keeping mosquitoes away are their leaves, which release a mint-like smell when they're agitated. So, these drought-tolerant perennials can keep mosquitoes away, but if you crush a few of their leaves when you're sitting or playing outside, they'll do double duty in making a mosquito barrier.

Catnip (Nepeta cataria)
    Catnip does more than just delight your feline companions. It's a member of the mint family, but looks and smells a bit different than your typical mint varieties-though works just as well as a pest deterrent! Fast and easy to grow, they're also prone to taking over patches of your garden, so stick to containers-or be ready for lots of catnip in a hurry.

Lemongrass (Cymbopogon citratus)
    Somehow, the natural oils in Cymbopogon citratus manage to smell like real lemons, only better. Grassy and abundant with a bright citrus scent, lemongrass is known for its higher potency of citronelal, the oil that deters mosquitoes.
    Versatile for use in cooking and adding lovely fragrance to your porch, you can cut some fronds and scatter them nearby before a gathering to help repel mosquitos. Coarsely chop the strappy leaves of this plant and strew them around your deck during your next gathering, both for mosquito-repelling power and for the pleasing aroma.
    When choosing between lemongrass and other plant-based mosquito repellants, lemongrass is often one of the best options for gardeners who are just beginning to experiment with mosquito repelling plants.

Citronella (Pelargonium citrosum)
    You're probably familiar with citronella candles, but might not realize that their strong fragrance, which is believed to be objectionable to mosquitoes, is extracted from the leaves of the citronella plant, also called mosquito plant.
    The mosquito-repellent citronella plant has a grassy appearance.Grows well in zones 9-11; annual in other zones. Plants are drought-resistant. Grow in afternoon shade and rich, fast-draining soil.
    For more information on the effectivness of Citronella as a mosquito repellent see "Does Citronella Actually Work? Here's What Science Says" from Southern Living Magazine

Marigold (Tagetes spp.)
    These bright and summery flowers, a staple for annual lovers, also happen to help with your mosquito-fighting goals. The substance in marigolds that gives them their insect-repelling power is pyrethrum, the same substance used in many organic insecticides.
    Liven up your patio with multi-colored blooms, especially around the borders of your patio, balcony, or yard, because these flowers are incredibly powerful at keeping pests away. In fact, studies have shown they have a negative effect on more than just mosquitos, deterring aphids, thrips, squash bugs, and many other garden destroyers.

Lantana (Lantana camara)
    Lantana flowers have such a potent effect against mosquitoes a scholarly journal published a report about it. The Journal of the American Mosquito Control Association (yes, there is such a journal) shares that "lantana flower extract in coconut oil provided 94.5 percent protection from Aedes albopictus and Ae. aegypti" mosquitoes.
    (Dua VK, Gupta NC, Pandey AC, Sharma VP. Repellency of Lantana camara (Verbenaceae) flowers against Aedes mosquitoes. J Am Mosq Control Assoc. 1996;12(3 Pt 1):406-408.)
    In fact, the study found this oil preparation protected the users from mosquitoes for an average of two hours. What a bonus that lantana flowers are so easy to grow in warm sunny locales, and attract butterflies as well.

Fennel (Foeniculum vulgare)
    An under-appreciated herb for home gardeners, fennel is delicious, fragrant, and versatile in the kitchen. The leaves host swallowtail butterfly caterpillars in the garden, and not to mention, it's thought to help fight mosquitos away.
    The plants grow large and grassy in appearance, providing a similar look and coverage as ornamental grass, but with beneficial bonuses. Hardy and perennial, these plants thrive in plenty of full sun.

Eucalyptus (Eucalyptus cinerea)
    As a native tree in Australia, the eucalyptus tree (Eucalyptus cinerea) can soar to 60 feet tall after several years. Because it's a tender plant that won't survive a hard freeze, the better alternative for many gardeners is to grow the eucalyptus as a potted plant.
    For short-term potting, choose a quick-growing species like E. globulus subsp. bicostata, which will give you many fragrant leaves to harvest for mosquito repelling. For a plant that will live for several years in a pot, choose a slow-growing eucalyptus like E. vernicosa. Eucalyptus plants like full sun and rich soil.

Basil (Ocimum basilicum)
    This beloved herb, famous for enhancing Italian dishes, sauces, and more, also happens to play a secret second role as mosquito repellant. The pests are repulsed by basil leaves, while humans love their bright fragrance and ability to improve many dishes. Fickle in some climates, basil thrives best with plenty of full sun and moist, well-draining soil.
    Not all basil types are created equal when it comes to repelling mosquitoes, and the extra-spicy Thai basil, with its narrow foliage and cinnamon scent, has the best ability to fend off insects. See also: Thai Basil vs. Basil: What's the Difference?

Thyme (thymus)
    Thyme continues the list of savory herbs that repel mosquitoes. Plant thyme between stepping stones in the garden, where your steps will crush some leaves and release the mosquito-repelling oils.

Scented Geranium (pelargonium)
    Scented geraniums include many varieties of Pelargonium (garden geranium) bred for their pungent scent. Those with a lemon scent are known to be best for repelling mosquitoes and other insects. Scented geraniums are perennial in warmer climates but are more often grown as annuals. They are especially popular as potted plants.

Ageratum (Floss Flower)
    Ageratum, commonly known as floss flower, contains a chemical known as coumarin, which can repel mosquitoes just by growing in the garden. Planting ageratum around a patio or in pots on your deck will help discourage mosquitoes. The same chemical makes the plant toxic, though, so be wary if you have pets that like to chew on plants.
    Ageratum was once primarily a low bedding plant, but there are now cultivars such as 'Blue Horizon' that grow to heights of 2 feet or more, giving you more options for using them in your gardening.

Sage (Salvia officinalis)
    Sage is a perennial herb with a semi-shrubby growth habit. It has a pungent yet pleasant odor that mosquitoes avoid. Leaves tossed into a fire pit will keep bugs away for hours. Over time, garden plants can become woody and sparse; prevent this by dividing the plants every few years.

    Another member of the Allium family of plants, garlic works in the same way as ornamental allium, offering some protective value against mosquitoes merely by growing in the garden. Like other members of the allium family, garlic is toxic to animals, so make sure your pets don't gnaw on the leaves, flowers, or bulbs.

Pennyroyal (Mentha pulegium)
    Pennyroyal (Mentha pulegium) is a spreading ground cover plant closely related to spearmint. Its scent is similar to that plant, and is so repugnant to mosquitoes that this species is sometimes called mosquito plant. It is not an especially attractive garden specimen, but it makes for an easy-care, effective ground cover, emitting a bug-repelling scent whenever you step on it.
    This is one of the most effective of all bug-repelling plants, but avoid growing it where pets might chew on it-the oils are toxic.

    For more information on the effectiveness of these plants as mosquito repellents see "Plants & Herbs as Mosquito Repellents" from Mosquito Reviews.

Not all of these plants will thrive in the South Louisiana climate, but many will and there's even a chance some of the thumbs-up plants may run a few mosquitos off!