TEXAS CERTIFIED EXPERT GARDENER — Repel mosquitoes with these natural plants  

Published 12:02 am Wednesday, May 22, 2024

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As anyone who enjoys the outdoors in SETX, especially during the warmer months, are forced to contend with one of Nature’s most extreme annoyances, the mosquito.

It’s amazing to me how such a diminutive flying insect creates such a widespread burden for man and beast! Gardeners, we devote a substantial amount of time doing what we love doing: planting flowers & vegetables, harvesting crops, amending soil, mulching beds, lawn care, and weeding (placed last as there are no gardeners that I know who enjoy this necessary task).

It seems we are under attack each time we venture outdoors to perform necessary tasks. Let me further state I detest using mosquito repellents but forced to do so to keep the ‘little demons’ at bay while grumbling inaudibly, so no one can hear the precise language used to describe what I believe to be an ever-increasing mosquito population. Each time I witness our county ‘Mosquito Patrol’ aircraft in the late evenings, I’m filled with hope (momentarily) which is quickly soured once a multitude of mosquitos begin another feeding frenzy (at our expense) having insatiable appetites!

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There are numerous plants we can use that act as short-term repellents and when strategically placed that may help deter mosquitoes. Learn what you need to know to make the most of mosquito-repelling plants.

Marigolds – are bright and colorful plants, easy-to-grow additions to all gardens. They are annuals, which provide long-lasting seasonal color. Marigolds release chemical compounds (like an organic insecticide) that many insects find offensive, including mosquitoes.

This is why marigolds provide such a strong odor when touched. The entire plant produces chemicals, but it is more concentrated in the blooms, which deliver the greatest amount.
Several other insect types are deterred which include aphid, whitefly, thrips, tomato hornworm, tobacco hornworm, Mexican bean beetle and squash bug. Adding marigolds to planters and vegetable garden spaces to help reduce the insect populations.

Bee Balm (monarda) – is a perennial that butterflies, bees, and hummingbirds find irresistible enjoying the large quantity of nectar provided. Bee Balm is also highly effective at repelling mosquitoes. Often plants must have leaves crushed to release volatile oils for insect repellent properties, which is not the case as Bee Balm is an exception.

As it grows & blooms it releases aromas mosquitoes dislike (basil has identical characteristics which this gardener uses extensively throughout all garden areas). Bee balm is a perennial that flowers in a variety of colors and plant sizes.

Variegated Plectranthus (Plectranthus madagascariensis ‘Marginatus’) – warning! If you’ve never cultivated this plant, it is highly odiferous! Okay, okay, okay…it’s extremely “smelly”, a slight brush against the leaves of the plant or a splash of water (including rainfall) releases the ‘odor.’

The odor helps to repel mosquitoes, and many other insects. The plant has numerous names such as Madagascar spur flower, Swedish ivy and mint leaf.

Scented Geranium are a group of plants with a wide variety of plant sizes and foliage forms but offer interesting sensory ‘smell’ appeal. Flowers typically are smaller than ‘traditional’ geraniums.

Crush the scented geranium leaves to release volatile oils which have fragrances which include rose, peppermint, nutmeg, apple, citrus, and cinnamon. The citrus or ‘lemon-scented’ varieties have the most concentrated insect repelling characteristics. They make exceptionally beautiful container plants.

Catmint, often called Catnip is an essential oil, which has been scientifically proven to repel mosquitoes (ten times more effectively than DEET). Catmint is the ornamental colleague of catnip which has unfurling scented leaves and beautiful flowers.

Notably less attractive to cats than ‘true’ catnip, catmint possesses mosquito-repelling qualities. For the best mosquito-repelling results, plant it near outdoor seating areas and entryways where guests will brush against the plant to release oils.

Sage – there are numerous herbs which provide chemical compounds which repel mosquitos. Sage leaves can be crushed then rubbed directly onto skin or clothing for a natural insect repellent. Bundle sage stems (fresh or dried) and add them to a chiminea to create a ‘cloud’ of mosquito-repelling smoke.

No chiminea, no worries! Light one end of a sage bundle and allow it to smolder on a metal or fire-resistant tray. Substitute other herbs which repel in a similar fashion using basil, rosemary, thyme, or any mixed combination of the each.

Thyme – another herb with intrinsic insect resistant properties, Thyme, including ‘creeping’ varieties possess excellent repelling properties. Again, the leaves must be crushed to release the volatile oils. Place crushed stems strategically around outdoor seating areas or rub the leaves on skin and clothing. Another option is burning thyme leaves, to drive mosquitoes away and can provide protection for up to 90 minutes. Several thyme varieties such as Lemon, silver, English, and creeping — all offer a varying degree of mosquito protection.

Mint- as many gardeners know, mint is a ‘heavy-lifter’ in the garden, considered by many to be a workhorse sending many insects packing! Volatile oils are released when leaves are slightly bruised or when leaves are crushed. Rub the crushed leaves on skin and clothing or add leaves and stems into pockets of clothing. Mint can become invasive, spreading quickly.

Containment will be needed by using small planters strategically located to remedy mints’ invasive nature noting the containers (edge of pots) must be elevated at least two inches above the soil surface. There are many mint varieties to choose from including Pineapple, spearmint, lemon, or peppermint. Flowering mint attracts beneficial insects like butterflies and bees, which might be problematic near seating areas.

Let me note that I use companion planting to aid in reducing mosquito and insect populations, science doesn’t substantiate many claims that plants on their own repel mosquitoes!

This gardener believes some plant odors do in fact affect mosquitoes but have a limited effect since most plants have very low ‘odor concentration’ without bruising stems & leaves or smoldering the plants which will provide a greater impact. To me it seems unlikely that a plant 3 to 5 feet away, or located on a porch will keep mosquitoes away!

Gardeners should also note that some plants will attract mosquitoes, as both sexes (male & female) eat nectar from a wide range of flowers. It is the female mosquito who needs nitrogen (blood is a great source) for egg production.

Send Certified Texas Expert Gardener John Green your questions and please continue sending comments to jongreene57@gmail.com.