7 Best Plants That Keep Spiders Away Naturally – Indoor & Outdoor

This is not the article we set out to write. The plan was the usual seven-plant list. Then we went looking for the research behind it and could not find any.

So here is what the evidence actually shows, where the myth came from, and what to do instead — because the real answer is cheaper than seven pots of lavender and it works.

Where this claim came from: a missing word

There is a large body of research showing essential oils kill Tetranychus urticae, the twospotted spider mite. Lavender oil performs well against it — in some trials above 90% toxicity.

A spider mite is not a spider. It is an acarine, in the subclass Acari, closer to a tick than to anything that spins a web in your porch corner. It is a plant pest that damages leaves, roughly half a millimetre long.

Drop one word from "lavender oil is highly effective against spider mites" and you get a sentence that has now been copied across the internet for the better part of fifteen years. Every listicle citing "studies" is, as far as we can trace, ultimately pointing at mite research.

What the research says about each plant

Two questions have to stay separate, because nearly every article merges them. Does the living plant do anything? And does the concentrated essential oil do anything? These are not the same claim.

Nought out of seven as living plants. Two of seven have limited laboratory evidence as concentrated oils. Three have never been put in front of a spider at all.

The lemon problem

In 2018, researchers ran three spider species through a Y-tube olfactometer to test the folk remedies directly — the study is "Natural Compounds as Spider Repellents: Fact or Myth?" in the Journal of Economic Entomology.

Peppermint oil and chestnuts repelled two of the three species in over three-quarters of trials. Both did nothing to the third.

And lemon oil — which the authors noted returns over a million search results as a spider remedy — had no effect on any species tested. The single most recommended natural spider repellent on the internet failed outright. Popularity and evidence are running in opposite directions here.

Why a plant can't do what the oil does

Even where oils work in a laboratory, the gap between that and a plant in a pot is not a small one.

Essential oil is an extract. It takes kilograms of plant material to produce a small bottle. In these studies it is presented neat, in a sealed tube, with the air saturated and nowhere for it to go. A shrub in a bed releases a tiny fraction of that into open air that is moving.

Clemson's horticulture team put the mechanism plainly: the fragrance a plant emits dissipates into the air and can be minimised with a breeze, and for any effect at all the leaves have to be crushed or the oil rubbed directly on skin. Reviewing 62 studies of plant essential oils, they noted that none of them examined landscape plantings.

There is a second problem, and it is more fundamental. Spiders are not insects. Most botanical repellents act on the insect odorant-receptor family, and spiders do not have it — they detect airborne chemistry through pore sensilla on their legs, a system evolved mainly for finding mates. The curator of arachnology at the Burke Museum puts it bluntly: spiders seldom show any sign of detecting airborne odours at all.

The chrysanthemum case, since it's the one with a real compound behind it

Pyrethrins are genuinely derived from a chrysanthemum, so this claim feels the most credible. It breaks in four separate places:

1. Wrong species. Pyrethrins come from Dalmatian pyrethrum, Tanacetum cinerariifolium. The fall garden mum sold across the Carolinas is Chrysanthemum × morifolium — a different plant, and not a commercial pyrethrin source.
2. Wrong part, tiny amount. The compound concentrates in the dried flower heads, at roughly 0.1% to 1.35% of dry weight. Leaves and stems on a living plant are not a delivery system.
3. Wrong mode of action. Pyrethrin is a contact poison. It has only slight repellent activity and breaks down fast in sunlight, so it cannot work as a passive perimeter.
4. Wrong animal. Where pyrethrum does repel, it works partly through insect odorant receptors — the receptor family spiders lack. Spiders do not appear on the pest list for pyrethrin products.

The advice that actually works: change your bulbs

Here is the thing the plant lists miss. Spiders go where the food is. Porch lights pull in insects all night, and web-builders set up exactly where that traffic concentrates — which is why the webs are always around the light fixture, the door frame and the windows.

Cut the insects and you cut the spiders. Clemson says it directly: replacing exterior white lights with a less attractive yellow or sodium vapour lamp can indirectly reduce the number of spiders. Penn State, UC IPM and the National Pesticide Information Center all give the same advice.

Those figures come from a study of more than 15,000 insects across 763 species groups. Two honest notes on them: the reduction measured was in insects, not spiders — the step from fewer insects to fewer spiders is the inference the extension services make, and we are repeating it as theirs. And the trial ran in a tropical forest, so treat the numbers as direction and scale rather than a promise for your porch.

One genuinely counterintuitive finding worth knowing before you buy: "warm white" on the box does not mean low insect attraction. A 2015 study compared bulbs at the same 2700K colour temperature and found significantly different arthropod attraction between them. Colour temperature tells you what the light looks like, not what it does to insects. What matters is how much blue and UV the spectrum contains — so look for true amber, not "soft white".

The rest of what the extension services recommend

• Knock the webs down. NC State calls a broom or a burst from a garden hose adequate control on its own. Penn State recommends a high-pressure water stream across the building. This is the primary recommendation, not a supplement to one.
• Seal the way in. Weatherstripping, a proper door sweep, sealed cracks around windows and the foundation. Clemson's line on wolf spiders is that exclusion is the best strategy.
• Dry the damp places. Cellar spiders want humidity. A dehumidifier or better crawlspace ventilation removes the conditions rather than the individuals — which matters in the Lowcountry.
• Clear the harborage. Move firewood, flowerpots and buckets off the wall. Keep leaf litter and clutter away from the foundation.
• Vacuum indoors. Baseboards, corners, behind furniture. It removes webs, egg sacs and spiders in one pass.

Note the awkward implication for the plant advice. UC IPM tells homeowners to keep the foundation line clear of heavy vegetation and to trim plant growth back from the structure. Ranking seven pots of shrubby herbs along the wall is closer to the opposite of the professional recommendation than it is to following it.

So should you pull the lavender out?

No — just do not expect it to do this job. The plants on that list have real merits, they are simply not arachnological ones.

Lavender, basil, rosemary and mint are excellent for pollinators and beneficial insects, provided you let some of them flower. Penn State's Master Gardeners list them among the herbs that feed bees, butterflies, lacewings, ladybugs and parasitic wasps. There is a trade-off worth knowing: culinary quality falls once herbs bolt, so the pollinator benefit and the kitchen benefit compete a little.

Crushed leaves rubbed on skin may buy short-term relief from mosquitoes, though Clemson's own figures put rosemary oil at around fifteen minutes and lemongrass at around forty. Plant them for the cooking, the scent and the bees. Just do not plant them as pest control.

Two more things worth knowing

Most indoor spiders never came in from outside. House spiders are a distinct indoor-adapted fauna that mostly arrive as egg sacs on furniture and building materials. A perimeter of plants targets a route the majority of them never used.

The autumn spider surge is not about cold. It peaks in late summer, and it is mating season — males wandering in search of females, not spiders fleeing the weather. This matters because it explains why a remedy tried in September always seems to work a few weeks later. The season was ending anyway.

When it is worth calling someone

• Webs keep returning within days of clearing them, which usually means an insect problem feeding them.
• You are finding widow spiders — smooth cream sacs, or spiky ones like a sandspur — where children or pets go.
• The activity is in a crawlspace or basement you cannot easily reach or keep dry.

Our spider control service covers South Carolina, North Carolina and Virginia, and the work is what the research points to: clearing webs and harborage, cutting the prey supply, and sealing the gaps. If you have found sacs rather than spiders, how to identify and remove spider egg sacs covers that specifically, and where spiders like to hide lists the spots worth checking first.

Further reading: Clemson Cooperative Extension's Home & Garden Information Center addresses this exact question — Can Plants Repel Problematic Insects? (Clemson HGIC).