Mosquito repellent plants

The short answer is no, and it is worth understanding why

Citronella plants, scented geraniums, lemongrass, lavender and marigolds are all sold as mosquito repellent plants. Planted in a bed or standing in a pot on the patio, none of them meaningfully reduces the mosquitoes around you.

Extension guidance is direct about the mechanism. Citronella oils are only released when the leaf is touched, so plants growing in containers on a patio or deck do not repel mosquitoes. To get any effect, the leaves have to be crushed or the essential oil rubbed on skin.

Clemson makes the same point about the scented geraniums specifically: they are not effective, because the essential oils in the leaves are not released into the air.

The evidence base is thinner than the marketing suggests. A meta-analysis of 62 studies on plant essential oils and mosquito repellency found only six carried out in the field and 56 in laboratories, and none of them examined landscape plantings at all. So the claim is not so much disproven as never tested in the form it is sold in.

What the plants actually contain

The compounds are real. Citronella oil does repel mosquitoes, which is why it appears in registered repellent products, and lemon eucalyptus oil is effective enough to sit on the CDC’s list of recommended active ingredients.

The gap is between a compound in a leaf and a compound in the air around your ankles. A living plant releases a tiny fraction of its oil passively, and whatever it does release is dispersed by the faintest breeze. Extension guidance notes that fragrance emitted by plants dissipates into the air and is minimized by any wind at all.

Crushing a handful of leaves and rubbing them on your arms does work briefly, and that is a genuinely different activity from planting the species and expecting it to do the work.

What actually reduces mosquitoes in a garden

Almost all of it is about water, because a mosquito needs standing water for 7 to 10 days to complete its development. Removing the water is the only intervention that reduces the population rather than the bites.

1. Walk the property looking for water, weekly

   Iowa State’s instruction is to inspect water impoundments weekly, because that interval is shorter than the development cycle.

2. Empty the obvious containers

   Buckets, tyres, cans, plant pot saucers, wheelbarrows, tarpaulin folds, children’s toys and anything overturned that holds a cupful.

3. Clear the gutters

   A clogged gutter is the single most productive breeding site on most houses and the one nobody looks at.

4. Refresh bird baths and pet bowls every few days

   Not because they are dirty, but because seven days is enough for a generation.

5. Use Bti where water cannot be removed

   Bacillus thuringiensis israelensis is a bacterium specific to mosquito larvae, sold as dunks, and it is described as harmless to humans, pets, fish and other wildlife when used per label. It suits ponds, water butts and drains.

Beyond water, the measures that work are personal rather than horticultural: avoid the hour either side of sundown when activity peaks, wear light-colored loose clothing, and use a repellent with an active ingredient from the CDC list. Wash it off when it is no longer needed.

The list of things that do not work

Iowa State names these explicitly, and it is a useful list because most of them are sold on the same shelf as the plants.

• Citronella candles

  Minimal effect even within the smoke.

• Bug zappers

  Ultraviolet and black light traps kill enormous numbers of insects, and mosquitoes are a negligible fraction of them. What they mostly remove is moths and beneficial insects.

• Ultrasonic and electronic repellers

  Sonic devices do not work. This has been tested repeatedly.

• Purple martin houses and bat boxes

  Both are worth having for their own sake. Neither controls mosquitoes, which are a small part of either animal’s diet.

• Garlic and vitamin B supplements

  Dietary approaches do not repel mosquitoes.

Mosquito lawn spray and yard treatments

The paid version of the same wish, and it deserves a straight answer because it costs considerably more than a pot of citronella.

Backyard sprays and fogs do work, briefly. Most use a synthetic pyrethroid such as permethrin, and they kill the adult mosquitoes flying through the yard at the moment of application. The problem is what happens next: the spray does not reach the standing water where the larvae are, mosquitoes fly in from neighboring properties as soon as the residue fades, and the next generation is only days away. NC State Extension puts it plainly, that yard sprays are largely ineffective at providing lasting control, and Illinois Extension gives the working life as a few days.

The cost is not only the money. A pyrethroid does not distinguish between a mosquito and anything else.

• A Xerces Society and University of Nevada study found pyrethroid levels high enough to kill beneficial insects in 100 percent of yards sprayed by private companies.
• 75 percent of neighboring yards were contaminated too, through drift. The treatment does not stay on the property that paid for it.
• Pyrethroids are also toxic to fish and other aquatic life, which matters wherever a yard drains toward water.

So the trade is a few days of relief against killing the bees on the squash, the butterflies on the zinnias, and the predators that were eating something. For a one-off event, a targeted treatment a day or two beforehand is a defensible choice. As a standing subscription through the summer it is the least efficient thing on this page.

What actually keeps mosquitoes away from a yard

Ranked by how much difference each makes, which is close to the reverse of how much they are marketed.

Do weeds attract mosquitoes?

Indirectly, and the mechanism is worth knowing because it is the one piece of garden maintenance on this page that helps. Mosquitoes are not feeding on weeds. Adults need somewhere cool, shaded and humid to spend the daylight hours, and a patch of unmown grass, a dense untended border or a stand of tall weeds against a fence supplies that better than anything else in a garden.

Illinois Extension’s advice follows directly: avoid dense plantings, prune to increase air flow, and keep the grass mown. That will not remove a mosquito population, since the population is decided by the water, but it does make a yard less comfortable to sit in during the day, which is where the biting comes from.

What birds eat mosquitoes?

Fewer than the claims suggest, and this is one of the better-established disappointments in garden folklore.

Purple martins rarely feed on mosquitoes, and the reason is a scheduling mismatch rather than taste: mosquitoes are low fliers active around dusk, and martins feed on high-flying insects during the day. Diet studies find wasps, winged ants, some bees, flies, beetles, moths, butterflies and dragonflies. The familiar claim of two thousand mosquitoes a day has little in the research behind it.

Bats do eat mosquitoes and could not live on them, feeding mainly on moths and beetles. Dragonflies are the best case, because their nymphs are aquatic and prey on mosquito larvae as well as the adults being taken on the wing, so they work at both ends of the life cycle.

None of them controls a mosquito population. Fish, spiders, beneficial insects, bats and birds all take mosquitoes and provide some natural control, but mosquitoes are rarely a significant part of any of their diets, and none eats enough to produce a change a person would notice. Put up a martin house or a bat box because you want martins or bats. That is a good enough reason, and it is the honest one.

Vicks, Pine-Sol, rubbing alcohol and the rest

The household remedies circulate constantly and they all run into the same two problems, which are worth stating once rather than plant by plant and bottle by bottle.

First, anything volatile disperses. The reason growing plants do not work is that whatever they release is minimized by the faintest breeze, and the same physics applies to an open dish of anything else. To have an effect on a person, a repellent has to be on that person.

Second, none of these has been tested in the form it is recommended in. That is the finding behind the meta-analysis cited above: 62 studies of plant oils and mosquitoes, six of them in the field, none examining a landscape planting. Applied to skin at a known concentration, some of these compounds do repel; standing in a room with them does something else entirely, and mostly nothing.

Two specifics are worth naming.

• Lantana is sold alongside citronella and scented geranium and falls under exactly the same finding. In one Illinois study, people surrounded by plants marketed as mosquito-repelling had more mosquitoes land on them than the control group did. That is not evidence the plants attract mosquitoes, but it is decisive evidence they do not repel them.
• Sandalwood, usually burned as incense or a coil, is the same case as citronella one step further along. The oil is a real compound and the smoke is a real delivery method, but the effect is confined to the smoke itself, which is the finding Iowa State reports for citronella candles: minimally effective, and only while you are sitting in it. Outdoors the faintest breeze takes it away from you, and a person downwind of a burning coil gets whatever protection there is while everyone else gets none.
• Soapy water is often suggested for standing water, and it is not the treatment extension services recommend. BTI is, and it is worth using instead for a specific reason: it kills the larvae and leaves humans, pets, fish and wildlife alone, which detergent in a pond does not.

Nothing in this section is a claim that the remedies are dangerous. It is a claim that they occupy the time and attention that emptying the saucer under a flowerpot would have used better.

So should you plant them anyway

Yes, if you want them for what they actually are. Scented geraniums, lemongrass, lavender, rosemary and basil are good plants: fragrant when brushed, useful in cooking, several of them excellent for pollinators, and pleasant to have beside a seat.

So it is worth saying what each one is actually for, and how to grow it, since that is the next question for anyone who came here with a shopping list and is leaving without one.

Notice the pattern in the middle column: most of these want full sun and sharp drainage, which is the opposite of the damp shaded corner where mosquitoes actually rest. Planting them there to solve the problem puts them somewhere they will grow badly and do nothing.

The one siting rule that does earn its place: put the aromatic ones where they get touched. Beside a path, at the edge of a step, next to a chair arm. Their oils release on contact, so a plant nobody brushes past is a plant doing nothing at all, and one you rub in passing is at least giving you the scent you paid for.

Buy them for that. The honest position is that the planting is a pleasure rather than a pest control measure, and that the twenty minutes spent tipping out standing water will do more for your evening than any planting scheme.

Frequently asked questions

Do citronella plants repel mosquitoes?

Not as growing plants. The oils are released only when the leaves are crushed, so a pot on the patio does nothing. Extension guidance states this plainly, and the same applies to scented geraniums, lemongrass and lavender.

Does anything about plants help at all?

Crushing the leaves and rubbing them on skin gives brief protection, which is a different activity from planting the species. The compounds are genuine; the delivery method of a living plant is not.

What actually reduces mosquitoes?

Removing standing water, since mosquitoes need 7 to 10 days of it to develop. Walk the property weekly, empty every container, clear the gutters, refresh bird baths, and use Bti dunks where water cannot be removed.

Are bug zappers worth it?

No. Iowa State lists ultraviolet bug zappers among the things that do not work. They kill large numbers of insects of which mosquitoes are a negligible share, so the main effect is on moths and beneficials.

Is Bti safe around fish and pets?

It is a bacterium specific to mosquito larvae, described as harmless to humans, pets, fish and other wildlife when applied according to the label. That makes it suitable for ponds and water butts where emptying is not an option.