Land cress: holes eaten in leaves

What it is likely to be on land cress

1. Slugs and snails

   Candidate 1very common on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Slugs and snails
   • Garden Organic — Garden Organic (Henry Doubleday Research Association): Slugs — vegetable seedlings

   Checked 2026-08-13

   The most destructive garden pest in a wet British spring, and the one surrounded by the most confidently repeated advice that does not work. They shred seedlings overnight and leave irregular holes with slime trails nearby.

   Points towards it

   • · a dried slime trail across a leaf or the soil beside it is the one piece of evidence a slug always leaves and nothing else on this list produces
   • · slugs rasp irregular windows out of the middle of the leaf, often leaving the veins standing, rather than working in from the edge
   • · they feed on damp nights and a bed that stays wet keeps them active all week rather than for a few hours after rain
   • · an open bed at soil level is where they can reach a seedling from below

   Argues against it

   • · a beetle or caterpillar visible on the leaf in daylight is a better explanation than an animal that is never there when you look
   • · a tray on a windowsill indoors is out of reach of anything living in the soil — this rules it out entirely.

   Check this next

   Go out an hour after dark with a torch and look at the underside of the leaves and the soil at the base, then decide by the size of the plant rather than by the damage. Slugs rasp windows out of the middle of a leaf and leave a slime trail that dries silver by morning; nothing else here does both. Then ask how big the plant is: on a chicory or spinach seedling still on its first true leaves this is the whole crop, and on a courgette that has covered a square metre it is a few per cent of the leaf and can be ignored entirely.

   What to do now

   Protect the plants that are small enough to lose and leave the ones that are not. Raise the vulnerable crops in modules and plant out at four or five true leaves rather than sowing direct, water in the morning so the surface is dry by nightfall, and clear the boards, pots and long grass at the bed edges where they spend the day. Where a seedling row must be direct-sown, sow a spare stretch of it — replacements cost a fortnight and nothing else.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Slugs and snails — non-chemical control
   • Garden Organic — Garden Organic (Henry Doubleday Research Association): Slugs — barriers and habitat

   Checked 2026-08-13

2. Flea beetle

   Candidate 2very common on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Flea beetle
   • Garden Organic — Garden Organic (Henry Doubleday Research Association): Flea beetle on salad brassicas

   Checked 2026-08-13

   Tiny dark beetles that jump when disturbed and pit young brassica leaves with small round holes, giving a shot-holed appearance. Seedlings can be checked badly; established plants shrug it off, so the timing of the attack decides whether it matters at all.

   Points towards it

   • · the signature is dozens of round holes a millimetre or two across peppered evenly over the blade, so a held-up leaf looks like it has been fired at with dust shot
   • · the beetles work on the youngest, softest leaves and largely ignore old ones
   • · they are most active in warm dry weather, which is also when a salad sowing is least able to grow through it
   • · an uncovered direct-sown row in the open is what they find

   Argues against it

   • · slime points at slugs, whose holes are large, irregular and few rather than small, round and many
   • · cool wet weather suppresses them almost completely

   Check this next

   Count the holes and their size. Flea beetle leaves dozens of round holes one to two millimetres across scattered evenly over the leaf; slugs leave a few large ragged ones with slime nearby. Then brush a hand over the row on a warm day — the beetles are 2mm, metallic and jump like fleas when disturbed, which is unmistakable and takes a second to confirm.

   What to do now

   Cover the row with insect-proof mesh from the day of sowing, sealed at the edges, since the beetles arrive on foot and by short flights and a cover put on after the damage starts does nothing. Keep the seedlings watered so they grow through it — the same amount of shot-holing that halts a dry, checked row is invisible on one growing fast. Land cress is at its best as an autumn and winter crop anyway, and a September sowing largely escapes the beetle altogether.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Flea beetle — non-chemical control
   • Garden Organic — Garden Organic (Henry Doubleday Research Association): Mesh covers for salad crops

   Checked 2026-08-13

Narrow it down

This page lists everything at once, which is the right shape for reading and the wrong shape for deciding. The interactive tool asks one question at a time, starting with whichever would separate these causes fastest, and stops as soon as further answers would not help.

Opens with the plant and the symptom already set. Nothing you answer is stored or sent anywhere — the answers live in the address bar and nowhere else.

What this does not cover

These are the causes GrowingHQ holds rules for on land cress — not every cause there is. Where several problems look alike, the honest answer is often that they cannot be told apart by eye, and a page that named one would be guessing. If none of the above fits, the general holes eaten in leaves page lists causes across all plants, and the Land cress profile lists the problems it is prone to.