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Do Marigolds Deter Slugs? They Attract Them Instead

Marigolds are one of the plants slugs go for first, not a repellent. Why the myth persists, how gardeners use them as a trap crop, and what does work.

By Zakaria 3 min read Save to Pinterest — opens Pinterest in a new tab
A dense planting of red and orange French marigolds with their finely divided foliage
Photo: Ivan Georgiev, Pexels License, via Pexels
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Marigolds do not repel slugs. Slugs find marigolds delicious — which is exactly what makes them useful, just not in the way the question assumes.

Where the myth comes from

What marigolds do and do not do
EffectEvidence
Soil nematodesSuppressed by Tagetes root exudatesWell established; the basis of using marigolds as a green manure
WhiteflyModest deterrence from scentSome support, effect size small
Slugs and snailsAttractedAsk anyone who has planted a tray out in April

Two of those three are true, which is enough for “marigolds repel pests” to become general folklore and for slugs to get swept in with everything else. They are the exception.

Using the attraction

A trap crop works because the preference is reliable:

  • Plant cheap bedding marigolds in a row a metre or two from the crop you are protecting
  • Water them well — slugs go for lush, soft growth
  • Collect after dark with a torch, or lay a board beside them and collect underneath each morning
  • Expect the marigolds to be eaten. That is the mechanism, not a failure

Trap cropping only helps if you remove what it gathers

A trap crop with nobody collecting from it is a slug feeding station next to your lettuce. The collecting is the control; the plant just decides where.

Plants slugs genuinely tend to leave

Tough, hairy, aromatic or bitter:

  • Herbs: rosemary, lavender, thyme, sage, fennel
  • Perennials: euphorbia, hardy geranium, astrantia, foxglove, aquilegia
  • Structure: ferns, ornamental grasses, bergenia

Avoidance is relative. In a wet spring a hungry slug tries things it normally ignores — but planting these where pressure is worst measurably reduces losses.

What to do instead

  • Hand collect after dark on damp evenings. Nothing else comes close, because it removes animals rather than relocating them
  • Boards, tiles or grapefruit halves as daytime shelters you empty each morning
  • Ferric phosphate pellets — effective and comparatively safe for pets and wildlife
  • Beer traps, which work but only within a small radius, so they need to be numerous
  • Predators: hedgehogs, frogs, toads, ground beetles, song thrushes. Leave some cover, keep a little water, and avoid metaldehyde pellets, which work up the food chain

Coffee grounds and crushed eggshells are the two most repeated remedies and the two least worth the effort. A slug glides over a blade edge on its own mucus; a scattering of shell fragments is not the obstacle it looks like.

Common questions

Do marigolds deter slugs?

No — the opposite. French and African marigolds are among the plants slugs and snails find most attractive, and newly planted marigolds are often shredded overnight while tougher neighbours are untouched. The confusion comes from marigolds' genuine reputation against other problems: Tagetes root exudates suppress some soil nematodes, and the strong scent has a real if modest effect on whitefly. Neither of those has anything to do with slugs.

Do slugs eat marigolds?

Enthusiastically, especially young plants. Soft new growth and freshly planted seedlings are the most vulnerable, and it is common for a tray of marigolds put out in spring to vanish within a night or two. Established plants with tougher stems survive better but still show the ragged holes and silvery trails that identify slug damage.

Can marigolds be used as a slug trap crop?

Yes, and this is the one genuinely useful thing they do here. Because slugs prefer them, a ring of cheap marigolds planted a little away from a vulnerable crop concentrates slugs in a predictable place, where they can be collected after dark or in the morning under a board. It is sacrificial planting, not repelling — the marigolds get eaten, which is the point.

What plants do slugs actually avoid?

Slugs tend to leave alone plants that are tough, hairy, strongly aromatic or high in bitter compounds: rosemary, lavender, thyme, sage, fennel, euphorbia, ferns, hardy geraniums, astrantia, foxglove and most ornamental grasses. Avoidance is relative rather than absolute — a hungry slug in a wet spring will try things it normally ignores — but planting these where slug pressure is worst genuinely reduces the losses.

What actually works against slugs?

Hand collecting after dark on damp evenings does more than anything else, because it removes the animals rather than moving them. Beer traps work in a small radius, boards or upturned grapefruit halves give a predictable place to collect them each morning, and ferric phosphate pellets are effective and comparatively safe. Encouraging predators — hedgehogs, frogs, toads, ground beetles, song thrushes — is the durable version, and means leaving some cover and not using pellets that harm them.

Do coffee grounds or eggshells stop slugs?

Barely. Both are widely repeated and both perform poorly in practice: eggshells are crossed easily by an animal that glides over a blade edge on its own mucus, and coffee grounds have only a slight effect at concentrations well above what a kitchen produces. Copper tape works in a confined setting like a pot rim, provided the pot is clean and nothing bridges it. Time spent on barriers is mostly better spent collecting.

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