A row of peas or broad beans sown one evening can be gone by morning, seed and all, with only a few scattered husks left on the soil surface to explain it. It's mice or voles, not a disease or an insect. Every method of controlling them involves killing the animal, so barriers and tolerance are the actual recommendation here, not a fallback.
A wood mouse, the common mouse species in UK gardens. Voles look visually distinct, rounder-bodied with a shorter tail and smaller ears, and no vole-specific photograph is included here.
Telling mice from voles
Mice have tails longer than their bodies and an extended, forward-facing head. Voles have a shorter tail and a rounder head in profile. Four species turn up in British gardens: the wood mouse, the short-tailed vole, the bank vole, and, mainly in southern England and Wales, the yellow-necked field mouse. For a gardener working out what's eating the seed bed, the distinction rarely changes what to do about it, but it's useful for knowing what's actually there.
What the damage looks like
Paired grooves from gnawing incisors show up on stems, corms and stored fruit. Holes appear in soil where they've dug down to reach germinatingA seed sprouting: breaking dormancy and putting out its first root and shoot, given the right warmth and moisture. Full definition → seed. Pea and bean seedlings can vanish overnight, leaving only scattered remnants on the soil surface rather than any obvious sign of an animal at work, since both species are active mostly at night. In cold weather they move into greenhouses and cold frames looking for shelter and food, and a single visit there can wreck many seedlings in one go.
Why this matters in Scotland
Peas, broad beans and sweetcorn are all staples of a Scottish vegetable garden, and all get direct-sown, which is exactly what puts them in the way of this. Peas and broad beans share the same vulnerable window: recently sown seed and fresh seedlings, so sowing indoors sidesteps the risk on both. Sweetcorn's attack window is entirely different: mice go for the ripening cobs alongside birds, squirrels, rats and badgers, not the seed, so indoor sowing does nothing for that crop, and a cob cover is what actually matters there.
Strawberries and apples are also grown widely in Scotland, but mice and voles don't show up as a real problem on either, only on peas, broad beans and sweetcorn. The same is true of french beans and runner beans: it's specifically broad beans that carries the risk, not beans generally.
Controls: what actually works
All the measures here are backed by real evidence.
Sow vulnerable seed (peas, broad beans, sweetcorn) indoors in modulesA tray divided into small individual cells, each sown with its own seed or seedling, so each plant grows undisturbed roots until it's ready to plant out. Full definition → or pots rather than direct into open ground
This removes the exact vulnerable window entirely, seed and very young seedlings at ground level: nothing is exposed at soil level until the plant is well past the stage a mouse or vole can destroy outright.
Use barriers over vulnerable sowings and contained, rodent-proof storage for harvested produce
This is the preferred alternative to lethal control: a barrier a mouse or vole physically can't get through works without the ethical cost of trapping or poisoning.
On sweetcorn specifically: net plants once cobs form, or cover individual cobs with bags or cut plastic bottles
Sweetcorn's real exposure isn't the seed stage the way peas and broad beans are: mice go after the ripening cobs themselves, alongside birds, squirrels, rats and badgers, so indoor sowing doesn't remove the risk here the way it does on the other two crops. Individual cob covers work because they physically block access at exactly the stage that matters.
Tolerate low populations rather than controlling them
Populations are normally low and don't sustain at a high level for long, kept there by a wide range of natural predators, so intervention often isn't solving a problem that would otherwise get worse on its own.
Myths about mice and voles
6 common claims about mice and voles, checked: 4 busted1 disputed0 untested1 hold up
“Soaking cotton balls in peppermint oil, or planting mint nearby, keeps mice and voles out of the garden or shed for good.”
A controlled maze test on house mice found peppermint oil and menthol did produce a real avoidance effect in the first week, mice spent less time in treated areas and took longer to enter them. That effect had disappeared by week one: the study reports peppermint oil and menthol failed to maintain their repellent activity once the initial cold-receptor effect of the menthol wore off.
Our read The short-term result is real, not imaginary, which is why the myth persists. But a repellent that stops working within days isn't a workable control for a whole growing season, and mice adapt quickly once food or shelter is worth the discomfort.
What to do: Don't rely on peppermint oil as the season's protection. Use a physical barrier over vulnerable seed and contained storage for produce instead, methods that don't lose effect as the scent fades.
1 source
- Natural and Life Sciences Communications, Chiang Mai UniversityPeppermint oil and menthol repelled mice in week 0 but failed to maintain repellent activity by week 1 in a radial arm maze test.
“Plug-in ultrasonic devices drive mice and voles out of the shed, greenhouse or garden.”
McGill University's Office for Science and Society reviewed the evidence for ultrasonic pest repellers and concluded the devices have never been proven to actually work. Some animals habituate to the noise within days and others aren't bothered by it in the first place, so any early effect doesn't hold.
What to do: Skip ultrasonic devices for mice or voles. Barriers, contained storage and sowing vulnerable seed indoors until it's past the seedling stage are the methods with an actual evidence base behind them.
1 source
- McGill University Office for Science and SocietyUltrasonic pest repellers have never been proven to work, since animals either habituate to the sound or aren't bothered by it to begin with.
“Scattering mothballs around the shed, greenhouse or store keeps mice and voles away.”
Mothballs are an EPA-registered pesticide labelled for moth control inside tightly closed containers only. The National Pesticide Information Center is explicit that using them anywhere else, including scattered outdoors or in a shed to deter rodents, is off-label and illegal, and that doing so can contaminate soil, plants and water and harm children and pets.
Our read The claim fails on its own terms before effectiveness even comes into it: using mothballs this way is against the product's legal label, not just a folk remedy that might or might not work.
What to do: Don't use mothballs outside their labelled purpose. Rodent-proof storage and barriers over vulnerable seed are the legal, sourced alternative.
1 source
- National Pesticide Information CenterUsing mothballs outdoors or for any purpose not on the label, including deterring wildlife, is illegal and can contaminate soil, plants and water and harm children and pets.
“Live-capture trapping mice or voles yourself and releasing them is a hassle-free method with no rules to follow, unlike poison or snap traps.”
Live-capture traps for small mammals in Scotland are governed by the Animal Health and Welfare (Scotland) Act 2006, not a rules-free option. Scottish Government guidance sets out a concrete duty from that law: traps must be checked at least once every 24 hours, and any animal caught, including non-target catches, has to be released or humanely dispatched promptly rather than left.
Our read RHS itself doesn't name trap-and-release as its recommended method at all; it points toward barriers and tolerance instead and leaves lethal control methods to RSPCA guidance rather than detailing them. The welfare obligations around live trapping exist precisely because leaving a trapped animal unchecked causes real suffering.
What to do: If using a live-capture trap, check it at least every 24 hours as the law requires, and release or dispatch whatever it catches promptly rather than treating the trap as fit-and-forget. Barriers that stop mice or voles reaching seed in the first place avoid the welfare question entirely.
In Scotland: The 24-hour check duty comes from Scottish, not RHS, sourcing, worth keeping separate from RHS's general tolerance stance in the main pest entry.
1 source
- Scottish Government, Rural Payments and ServicesLive-capture traps for small mammals are covered by the Animal Health and Welfare (Scotland) Act 2006, requiring traps to be checked at least once every 24 hours and non-target animals released or humanely dispatched.
“Keeping a cat in the garden keeps mouse and vole numbers down.”
RHS names cats among the wide list of predators, alongside foxes, stoats, weasels and owls, that it credits with keeping garden rodent populations naturally low. A peer-reviewed field study of rodent foraging around homesteads found something narrower: cats alone, without a dog also present, produced no measurable change in rodent activity. The reduction only showed up where cats and dogs were both present, and even then the study measured a drop in foraging activity, not a confirmed drop in rodent numbers.
Our read The two sources aren't strictly contradictory, RHS is describing a whole predator community over time, the study is isolating one predator's effect in the short term, but a single garden cat on its own isn't the mechanism either source actually credits with suppressing numbers.
What to do: Don't count on one cat to solve a mouse or vole problem. Treat a cat as one part of a garden's wider predator picture rather than a standalone control method, and use barriers for anything a cat can't reliably guard.
2 sources
- RHSMice and voles are heavily predated by cats, foxes, stoats, weasels, owls and other birds of prey, which is why garden populations stay naturally low.
- PLOS ONECats alone at a homestead produced no significant change in rodent foraging activity; a measurable effect only appeared where cats and dogs were both present together.
“Covering a newly sown drill of peas or beans with mesh or fine netting stops mice and voles digging up the seed.”
Mice and voles specifically target recently sown pea, bean and sweetcorn seed at soil level; barriers are the preferred way to prevent that damage without resorting to lethal control.
Our read RHS backs barriers as a category rather than naming mesh by product, so this is our reading of what a barrier means in practice for a sown drillA shallow, straight groove made in prepared soil for sowing seed into, at a set depth so germination and rows are even. Full definition →: something laid or pegged over the soil that a mouse or vole physically can't get through until the seedling is past the vulnerable stage.
What to do: Peg mesh or fine netting flush to the ground over the sown drill, or sow in modules indoors instead, and remove the cover once seedlings are established and past the point a mouse or vole can destroy them outright.
1 source
- RHSMice and voles eat the recently sown seeds of peas, beans and sweetcorn, and RHS recommends using barriers and contained storage to deter damage rather than killing them.
Frequently asked questions
How do I stop mice and voles eating my sown seed?
For peas and broad beans: sow indoors in modules or pots instead of direct into open ground, at least for the vulnerable early stage. Once a plant is past germination and into real growth, it's no longer the easy target a bare seed or fresh seedling is. Sweetcorn is different: mice go for the ripening cobs, not the seed, so indoor sowing doesn't help there, and covering individual cobs with bags or cut plastic bottles is the control that matters instead.
Should I trap or poison them?
Start with barriers and contained storage instead: they solve the same problem without the ethical weight of killing anything. If you decide you need to go further than that, the RSPCA's guidance on humane practice is worth reading first.
Will the population just keep growing if I do nothing?
Usually not: garden populations are normally low and don't sustain at a high level for long, kept in check by a genuinely wide range of predators, cats, foxes, stoats, weasels, owls and other birds of prey among them. Tolerating a low background level is often just letting that natural balance do the work.
Why do they suddenly show up in my greenhouse in winter?
Cold weather pushes them indoors looking for shelter and food, and a greenhouse or cold frame full of overwinteringKeeping a plant alive and intact through the cold months, whether left outdoors, moved under cover, or stored dormant. Full definition → seedlings is exactly what they're after. This is when a single visit can do the most damage in one go, since there's nowhere else for them to be.
Sources
4 sources, recorded with what each was used for
- RHS: identification, symptoms, host list, seasonal activity, life cycle, predator list, tolerance stance, barriers and contained storage, absence of detailed lethal control
- RHS: confirming mice and voles directly on broad beans' own growing page
- RHS: confirming mice and voles directly on peas' own growing page
- RHS: confirming mice directly on sweetcorn's own growing page