Compost Rats: How to Keep Rodents Out of Your Compost

Rats in your compost bin? We feel your pain. You’ve taken the time to build your compost pile from scratch, creating beautiful, rich compost for your garden that you just can’t wait to use in the next sowing season, and now some rodents have taken over!

If you’ve spotted rats in your compost piles (see below for signs to look out for) you need to act fast. They can start to gnaw their way into your house, your sheds, and outbuildings, and they can cause significant harm to your plants. They will get through wires, cables, and even some lighter forms of concrete to get to where they want to be. They can spread disease and terrorize your pets and family, making your outdoor space a no-go zone – oh, and they breed really fast.

Why Does Compost Attract Rats?

rat sitting in garden

Yes, compost can attract rats, but if you understand why, there are plenty of things you can do about it. Like most animals, rats are looking for two main things: shelter and food – and your compost heap may be providing them with a plentiful supply of both

The kitchen scraps and food waste you put in your compost bin are like an all-you-can-eat buffet for rodents, particularly if you’ve included meat in your food scraps. Additionally, many compost piles are too dry, which means they make a cozy place to put a nest.

Rats in compost often become a problem in the winter months, where the colder weather forces them to seek shelter. The warmth inside your compost, the easy access to food waste, and the fact that your heap gets drier in winter all contribute to making conditions perfect for any rat looking for a home. And as we share our planet with billions of them, this isn’t an unusual problem.

The good news is that with a little care, you can discourage and prevent rats from setting up home in your compost. Check out the tips we’ve provided below for some strategies you can use to discourage rats.

What Type of Rat Is In My Compost? 

In North America and Europe, you’re only likely to see the brown, or Norway rat (also known as the common rat). They’re adaptable, breed fast, and will eat almost anything humans do. You can find them almost anywhere, but they are particularly concentrated in urban areas where there is plenty of food and shelter.

Should I be concerned?

Yes. Rats carry all kinds of diseases, including Salmonella, Weil’s Disease, Listeria, Leptospirosis, rat-bite fevers, Cryptosporidium, and Tularaemia. A small amount of rat saliva or urine on your skin can be enough to pass disease – and if they’re in your compost, there’s plenty of opportunities to come into contact with them.

Additionally, your pets can pick up parasites, or worse, if chasing them becomes their new favorite hobby.

As if that wasn’t bad enough, rat populations can multiply fast. Real fast. The gestation period of a rat is only around 3 weeks. Female rats can give birth to litters of up to 14 rats and potentially give birth up to 10 times a year. That one rat can easily become 140, in under 12 months!

Could it be mice in my compost heap?

Yes, mice are also attracted to live in compost for the same reasons that rats are. They might look slightly cuter, but they also spread a wide range of diseases and should be discouraged just as strongly. As with rats, they’re attracted by food waste and the opportunity to get warm, so a mouse is particularly more likely to enter your heap during winter.

Spotting a Rat: 7 Signs There May Be Rats in Your Compost

Not sure if you have a rat of a mouse in residence? Here are a few tips for spotting them:

  1. Burrows and holes – Take a close look around your yard for any burrows or holes in corners of outbuildings or fences, or signs of burrowing in any quiet spots. 
  2. Potent smell – Many people claim that they can tell where rats have been because of the smell. If you think your compost heap smells a little bit different (and less pleasant), this could be a sign that rats are living there.
  3. Tracks and runs – Keep an eye out for any runs or tracks around vegetation. Carefully examine the area around your compost pile to see if you can find any entry or exit ways or pathways they’ve made. 
  4. Look up – Rats are adept climbers and could be using your greenhouse or cold frames as a rat superhighway. They’ll often prefer these routes as they keep them safe from predators.
  5. Look for damage – Are there any signs of new damage in your garden? Are your peat bags chewed anywhere? Or have corners of your compost bin been nibbled? Any damage to any fence panels or shed corners? Rats are often the cause.
  6. Rat poo – Where there’s rat poo, there are rats! It’s not easy to spot in a compost pile full of seeds and rotting materials, but rat poop looks like tiny dark pods, pointed at one end and flat at the other, about 1/2 an inch long (TMI?). A single rat can produce up to 40 of these in one night!
  7. Look and listen – Rats are nocturnal, so they’re most active at night. If you suspect rodents, take a trip out under darkness and listen out for them. If you want to get really high-tech, you could also set a night-vision camera on your compost pile to see the size of an infestation!

11 Ways to Discourage Rats From Living in Your Compost Bins

1. Upgrade your compost heap with a solid bin

Open compost heaps are incredibly easy for rats to get into. Instead, consider upgrading to a solid-sided container to make it near-impossible for the little critters to get in. Use a narrow-gauge wire mesh at the bottom and, if you’re composting kitchen waste, a robust and heavy lid.

2. Avoid putting cooked food in your kitchen waste 

The food scraps you put into your kitchen waste (and then into your compost) contribute to attracting rats and encouraging them to stick around because you’re feeding them food they like! This includes meat and other kitchen scraps – rats will eat anything. 

3. Keep your compost bin damp

During the summer, your compost tends to stay naturally damp. However, they often dry out over winter. This creates an ideal environment for rats looking to nest down somewhere warm and cozy. Adding a little bit of water will discourage rats (who wants a wet bed?) and help your compost to break down quicker – just don’t add too much, we’re aiming for damp, not flooded.

How often should you water it? It’s easiest to do it every time you aerate it – see below.

4. Aerate your compost regularly

Aerating your compost is recommended to help increase the amount of oxygen in your heap to aid decomposition. However, it also has a secondary benefit – it can help put off rats and mice from living there. How would you like it if every few weeks someone turn your house upside down? You can buy specialist tools to help you do this, but a fork can achieve a similar effect if you don’t want to splash out.

5. Move your compost bin

Most of us hide our compost away in a shadowy corner of our garden. But if you’ve got a rat problem, you might want to put it somewhere open. Yes, we know it’s not attractive to look at, but if you can place it somewhere that rats will be exposed when traveling to and from, they are less likely to go there. They are too vulnerable to predators if out in the open, and will prefer somewhere that they can come and go from undercover.

6. Reinforce the perimeter of your garden

Before rats can get into your compost to create a nest and eat your food waste, they have to get into your garden. If you have a safe, impenetrable garden, you’re less likely to have to deal with a rodent problem. Lay wire under fences to stop them from getting into your garden in the first place and block any holes and gaps in walls.

7. Use ultrasonic repellents

Ultrasonic repellents send out a high-pitched frequency which naturally repels all manner of small and furry pests. Different frequencies deter different animals, and one specifically for rodents should not disturb you or any pets you may have (check the packaging to be sure), but it should make life sufficiently uncomfortable to keep the rats at bay. 

These devices can cover a reasonable distance, and solar-powered kinds are available. Just make sure you buy enough to cover the surface area of your whole garden.

8. Put down leftover onions

If you have leftover onions, leave these around your garden too – rodents hate the smell, and it will keep them away. Any of the allium family of plants can be used in this way.

9. Enlist the help of a furry friend

While we’re talking of mint, why not plant catmint and get a cat? Rescue one from the local animal shelter and once they are safely settled in their new home and can go outside, let them take care of the problem for you. We can’t promise that they won’t come back home bearing furry ‘gifts’ for you, though. (But take comfort in knowing that it’s a sign that they think you’re a useless hunter and are trying to provide for you).

10. Consider upgrading messy bird feeders

Many bird feeder designs drop food scraps all over the surrounding area. Not only does it look a bit messy, but it also attracts rats. Often this happens when the size of the seed you’re using is not suitable for the holes in your bird feeder – when the seed is too small, it drops out too easily. 

If you’ve got one that does that, consider upgrading to a version that creates less mess or changing the seed you use so that it is less likely to fall out. You should also avoid seeds with husks since birds don’t eat these bits (they pick the seed inside out) and tend to drop them on the ground.

11. Set humane traps

As a last resort, or if your rodent problem is out of control, set humane traps. Avoid ones that use poison, as these can be damaging to any pets or the ground, soil, and plants around them.

Final Word

Whether you’re a rat lover or a rat hater, having them in your compost is not a good idea. Try not to make your vegetable garden their favorite local hangout (not to mention it being the party hangout of the local feral cats, on the lookout for a quick snack).

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