Fragrant Plants to Repel Mosquitoes

The weather has been bitterly cold lately, which has me daydreaming about spring baseball (The Grapefruit League) and planting season. As much as I love catching a few spring training games to break up the winter, I think about planting all year long—I just pretend that I don’t.

I’m usually drawn to perennial flowers because I adore plants that return year after year. Plus, I’m a sucker for anything that blooms. But sometimes, I have additional motives. I love fragrant flowers and plants, and as a bonus, some of those scents happen to repel mosquitoes and even blackflies!

As I plan what to plant and work on cold-stratifying my wildflower and perennial seeds, I’m also starting a few highly fragrant varieties. My hope is that they’ll help keep mosquitoes at bay, both at our summer cottage and at home in Southern Ontario. While I can’t promise these plants will fend off the hordes, any plant that mosquitoes dislike is a win in my book. AND – any excuse to grow more plants is a wonderful thing for a plant hoarder like me.

The alternative that seems to be the acceptable method is to dip yourself in DEET (PLEASE DON”T!!) which I won’t use but my husband does – funny how the critters seem to like him more too?

There is a bit of science backing up my plant – mosquito defence strategy! The fact is: the compounds in plants that deter mosquitoes and blackflies are primarily essential oils or aromatic substances that interfere with the insects’ sensory receptors. These compounds either mask the scents that attract the insects or repel them outright. In other words – plants that we think of as being strongly scented can distract those varmints from being attracted to us – or actually shoo them away! This sounds good to me.

Varmint Repelling Compounds:

Citronellal

Citronellal is known to interfere with mosquitoes’ olfactory receptors, making them avoid treated areas entirely. It is in Lemon balm, citronella grass, lemongrass, and lemon-scented plants like lemon eucalyptus.

Geraniol

Geraniol is a Potent mosquito repellent and works against some blackflies. Its strong floral aroma repels mosquitoes and biting insects by overwhelming their sensory system – is found in Geraniums (Pelargoniums – not Cranesbill), lemon balm, citronella grass, lemongrass, and strongly scented rose varieties. It’s also found in basil, thyme and lavender.

Linalool

Linalool repels mosquitoes and blackflies directly by disrupting their sensory receptor. It is found in lavender, basil, and thyme.

Carvacrol

Carvacrol acts as a broad-spectrum insect deterrent. It has been shown to repel certain insects, including mosquitoes, by acting as an irritant and overwhelming their olfactory system. Its strong aroma can mask attractants like carbon dioxide and human scent, discouraging insects from approaching or biting. It’s found in oregano and thyme.

Eugenol

Eugenol has strong insect-repellent properties, particularly for mosquitoes – Confuses and deters mosquitoes and other biting insects from settling. It is found in cloves, allspice and bay leaves.

Thymol

Thymol alters insect behavior by masking attractive scents like CO₂ or human sweat, reducing their likelihood of biting – found in Thyme and oregano.

Menthol

Menthol produces a cooling sensation that directly repels mosquitoes and other biting insects and is found in mint plants.

Camphor

Camphor repels mosquitoes and is believed to work on blackflies. Its found in camphor trees, rosemary, and some types of basil. It’s better known as a moth repellant in some mothballs.

Terpene

Terpene is found in pine,  cloves, black pepper, oregano, cinnamon, and basil. It’s scent is known to deter mosquitoes and possibly blackflies. I have pine trees everywhere! How could there be any mosquitoes at all?

Nepetalactone

Catnip (Nepeta cataria) is one of the most effective natural mosquito repellents, and also works against blackflies.

Pyrethrin

Pyrethrin, a compound found in Chrysanthemum family of plants is a natural pesticide. Now I’m not fond of pesticides, even when they are labelled as organic – but I know it occurs naturally in my garden flowers.

A Note about our Northern Island:

Before I move on to what I am growing – a note about our Northern Island. It is enveloped in beautiful low bush blueberries and very tall stately pine trees. The blueberries are actually an attractant to blackflies. (Not to mention the aggressive blueberry-eating mallards – who just seem to know when the berries are ripe). The blackflies enjoy visiting the blueberry flowers in the spring and drink their nectar! So while I’m dreaming of discouraging the bugs, the very nature of our island brings them to us.

What I’m growing:

So in light of all of that, here’s what I’ve got growing so far:

Lemon Balm (Melissa officinalis)

Easy to grow but can be invasive. These seeds have been my fastest sprouters this winter! These plants smell so good! Easy is the key!

Citronella Grass (Cymbopogon nardus)

This one is a little tricky to germinate but I’m working on it! It’s not cold hardy, so I grow this in containers to bring inside once cold weather hits. Citronella Grass is the classic plant that we think of to ward off mosquitoes and is very strongly scented. Even though I prefer hardy perennials – this grass is worth the effort.

Citronella Plant

Citronella plant, also known as Pelargonium graveolens, is the leafy plant that garden centres sell us to keep mosquitoes away. They even label it as “The Mosquito Plant”. It’s a member of the pelargonium/geranium family and not a perennial in our area (hardy to Zone 9). It does have citronellal and geraniol but in much lower quantities than Citronella Grass!

Lavender (Lavandula spp.)

I am building a cold hardy perennial lavender garden and can’t wait to see which varieties have returned to our Northern garden in the spring. I don’t need an excuse to grow lavender!

Catnip (Nepeta cataria)

Who knew that something that attracts cats keeps mosquitoes away. Max the Goldendoodle is hoping to meet some cats as well.

Basil (Ocimum basilicum)

I always have basil on the go because we use it so much in cooking.

Lemongrass (Cymbopogon citratus)

Wait a minute – isn’t that the same as Citronella Grass? NOPE!! This lemongrass is more often used in cooking, while Citronella Grass is the one we think of as an insect repellant and has a much stronger scent. I have been growing this one in pots to be brought inside when the weather is cool. This one is a little tricky to germinate too – but well worth the effort!

Did I mention it is often cited as a natural snake deterrent due to its citrusy scent? Live and let live I say but I really do not want to see any snakes!

Thyme (Thymus spp.)

I always have a little Thyme in my garden, but I mainly use it for cooking. I have a lovely variegated lemon thyme in Southern Ontario and a more generic variety in the North! Sometimes I sprinkle thyme seeds to make a walking path between stepping stones but I don’t find these to be as “perennial” as I hope they will be!

Mint (Mentha spp.)

Be cautious with invasive mint varieties in the garden. I confess, I have quite a few varieties of mint, in both of my gardens. I have Canadian wild mint and a non-native wild mint, spearmint, strawberry mint, apple mint and mohito mint! Maybe that’s too many. No it’s not…...

Canadian wild mint has the strongest scent of any of our plants, so I think I must have more of this plant! When we bring it inside for drying our whole cottage smells like Vick’s Vapor Rub! I love my growing mint collection so much that I think I will have a section of the garden devoted exclusively to mints. Would that be a “Minterie”?

Feverfew (Tanacetum parthenium)

Feverfew with it’s little white daisy like flowers is so pretty and grows where it likes. It is very strongly scented and it contains pyrethrin.

Yarrow (Achillea millefolium)

Known for its strong, herbal scent, yarrow is a native plant that is drought-tolerant and great for pollinators. It grows so easily, and it contains camphor to repel those bugs.

Wild Bergamot (Monarda fistulosa)

Bergamot, also known as bee balm, is a pollinator favourite and thrives in many regions of Canada. I have quite a few different types of bee balm, but they all contain Linalool, geraniol and thymol, and carvacrol. Bee balm, in all it’s varieties is beautiful and has a lovely spicy scent!

The most effective plants for repelling pests are those that produce plenty of foliage. While I always grow lemongrass and basil for cooking, I usually keep them in pots so I can move them around – since they aren’t hardy in my garden. I’m looking forward to seeing my lavender return this spring – to see how they did over the winter. Mint, oregano, thyme, bee balm, catnip and lemon balm, on the other hand, are reliable options that thrive and get the job done. Feverfew and Yarrow happily grow wherever they want.

I may not succeed in keeping all the mosquitoes away with plants, but they do give me a great excuse to grow more! It’s a handy explanation for curious neighbours and relatives. My husband fully supports my plant-filled reasoning as he knows that the more plants I have the further into Happy LaLa land I go!

Happy gardening!

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