Mice and voles are opportunistic feeders that are found in many gardens. If they discover the delicious food sources in your polytunnel, then you may have a problem on your hands. Especially early on in spring, and over winter, when there are fewer food sources around outside, you may find that rodents enter your polytunnel and nibble away on your crops.
Why Mice and Voles Can Be a Problem
Mice, voles and other rodents can be a problem in any fruit and vegetable garden. They can squeeze through the tiniest of gaps and can be quite voracious. Little rodents can quickly munch their way through a whole tray of seedlings, or eat all the seeds you have so carefully planted out. They can nibble soft fruits like strawberries before you get the chance to harvest them, and eat other fruits before they have been collected.
These rodents can be more numerous in our gardens than we may imagine. They usually only come out at night. So unless you yourself are nocturnal, you are unlikely to actually catch them in the act. It is likely that most of us are sharing our outside space with rodents without even knowing it.
Mice and voles won’t usually become a problem in your polytunnel unless food sources are scarce, and the population locally has boomed. With more rodents and fewer resources, these creatures are more likely to begin competing with humans for food.
In my wildlife-friendly garden, there are plenty of places for mice an voles to hide. While most of the time, these creatures do not trouble us, occasionally, they do become a problem. The main problem is that, in certain years, when spring comes a little later, mice and voles eat seeds and seedlings sown early in the polytunnel garden. I find that peas and broad beans are most affected. But I have also had voles eat early potatoes sown in the ground.
Keep Rodent Populations in Check
Getting to grips with a rodent problem in your polytunnel involves, first and foremost, taking steps to make sure that the population is kept in check. In extreme situations, trapping may be necessary. But it is often possible simply to work to restore a natural balance in the ecosystem.
Mice and voles are predated by owls, and other birds of prey. Making sure your garden is appealing to these predators is one of the best ways to keep mice and vole populations down. Build owl nest boxes and create a habitat suited to their habits.
Keeping chickens can also help. Chickens too will eat mice and voles when they come across them. Foxes will also eat mice – though will not be welcome visitors for those who want to keep chickens.
Generally, keeping a wildlife friendly garden will help with pest problems, as a natural ecosystem will tend to find an equilibrium. There will still be mice and voles to contend with, of course, but problems are far less likely to get out of control. It is vitally important not to put down poisons, as these can also impact on other creatures, and will throw the ecosystem out of balance.
Keep Mice and Voles Occupied Elsewhere
Planting plenty of food-sources for mice an voles elsewhere in your garden will also help. It will be especially beneficial to plant shrubs and sturdy perennials that will provide food sources in winter and early spring. When rodents have plenty of other things to eat, they are far less likely to make their way into your polytunnel and eat your seeds and plants.
Make Your Polytunnel Unappealing To Mice and Voles
First of all, mice and voles are more likely to enter your polytunnel if there is plenty of debris and clutter for them to hide amongst. So in order to keep them out, one thing you can do is give the place a good tidy up. When there are fewer places for them to hide, rodents will find your polytunnel a much less appealing place to forage.
Give the rest of your garden a bit of a tidy up too. Keep lawn areas close to the polytunnel mowed, and make sure wilder corners for wildlife are far away from the polytunnel.
It is also a good idea to avoid laying thick and airy mulches of organic matter over winter. Hold off until a little later in the year, when planting out in later spring. Mice and voles will enjoy having a mulch to tunnel under, and so may be attracted to forage where a mulch is laid.
Keeping snow cleared from around your polytunnel in winter will also help to make it harder and less convenient for voles and mice to make their way inside.
Another way to deter mice and voles is to sprinkle some cayenne pepper around your seedlings and vulnerable plants. Peppermint is also said to deter them. Rodents won’t like noises and vibrations either. So even placing a few garden windmills over vole holes, for example, might be enough to encourage them to move elsewhere.
Add Physical Barriers To Prevent Losses
A polytunnel will itself act as a partial barrier. But if mice and voles find their way inside, and find food sources, they’ll be sure to return. Repellents can act as a partial deterrent. But you may still find that physical barriers are required to prevent losses.
I sow beans and peas and other early sowings indoors before planting them out in the polytunnel. Later, I sow and grow seedlings not on staging that rodents can climb, but on a hanging shelf suspended from the crop bars on the polytunnel structure.
Then, I protect the young seedlings placed into growing areas with cloches made from household rubbish. Old plastic drinks bottles or similar can be ideal to protect individual plants. There are plenty of waste items that you can repurpose to protect your polytunnel plants from rodents early in the year.
Where voles are a particular problem, you may find that potatoes and other bulbs or tubers are best grown in containers or raised beds, with a wire mesh placed inside to prevent these creatures from tunnelling through.
Why Mice and Voles Can Also Be Beneficial in Your Garden
While mice and voles can be very frustrating. Especially when they are eating your seeds and your crops. But it is important to remember that they are also a useful, beneficial part of the garden ecosystem. It is best to think about how we can live with them, rather than thinking about trying to get rid of them altogether.
Voles and mice are an important food for owls, foxes and other wildlife. So counterintuitively, we need some around to prevent a population explosion in future. Voles also eat insects and weed seeds; so in this respect too, they can be helpful to gardeners.
Have you encountered mice or voles in your polytunnel? Have they caused problems? How have you managed the problem where you live? Let us know in the comments below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.
To get in touch, visit https://ewspconsultancy.com.