Some of our customers claim the Green Johanna is rat-proof as they have never had any problems with these unwelcome visitors.

That is the experience of most people, but since rats have been known to chew through concrete, glass and even some metals nothing can really be called rat-proof.

However, there are steps you can take to deter rodents by making your compost bin and garden so unattractive to them that they will move on to a more accommodating environment.

If there’s a problem with rats locally it’s worth checking whether a neighbour is exacerbating the issue by leaving food out for wildlife. This was the experience of one of our customers, who discovered that his next-door neighbour was getting animal bones from a butcher and leaving them in his garden overnight to feed foxes. The neighbour even thoughtfully left his garden gate open at night to encourage visiting wildlife. But foxes weren’t the only ones coming round for a feast.

 Such issues obviously need to be addressed first. If there is a persistent problem in your neighbourhood consider professional help to sort it out.   

The Johanna has been designed with an integrated base to deter rats. Using the Insulating Jacket also provides another layer of material as well as insulation to help keep temperatures high enough to discourage rats.   

As part of the Green Johanna’s and the Green Cone’s five-year guarantee, Great Green Systems will replace any parts that suffer rodent damage.

Recommended deterrents:

If you can, site your compost bin in an open, uncluttered area as rats hate being exposed. Open space makes them nervous.

• If you know there is a rodent problem locally, try to avoid siting the bin along fence lines or near log/brick piles and shrubbery or thick vegetation that provide protection for them. Rats have poor eyesight and use fences and walls to run alongside for direction.
• If there are overhanging trees, cut away the lower branches so they don’t provide means of reaching the bin.
• Protect the composter’s base – place paving slabs or bricks around the base. Placing thorny prunings around the composter will also make access difficult.  One of the Great Green Systems team swears by a barrier of spiky-leafed branches pruned from a Berberis Darwinii bush. (Wear gloves when handling and boots in case you step on them.)

• Rats hate noise and being disturbed, so bang on the bin with sticks every time you go past so they get the message this is not a peaceful place.
• One customer recommends creating a stockade fence of bamboo sticks around composters. Push each stick into the ground as closely as possible (easier to do after rain).
• Keep the bin active. If you’re going away ask someone to keep your composting activity going for you so the bin is not left undisturbed for weeks.  
• Ensure food waste is well chopped to provide more surface area for microbes and accelerate the breakdown process. Smaller pieces are also easier to stir and mix with garden and paper waste.
• After adding and aerating fresh contents, finish with a covering layer of shredded paper, cardboard or dead leaves to prevent smells attracting flies or rodents. You can also add mature compost or soil.
• Aerate composter contents regularly.
• Keep the mixture moist. Moisture levels should be around 50 per cent. You can use a moisture meter to check or do the ‘squeeze test’ – take a large handful of compost and squeeze. If one or two drops of liquid come out that is likely to be right – the compost should be the consistency of a wrung-out sponge. Add water if needed in summer months, preferably rainwater from a water butt.

• Place builders’ mesh (available at DIY stores and online) underneath the composter.  The Johanna already has an integrated base but mesh would provide an added deterrent.
• Rats hate strong smells so try planting mint round the bin and add mint leaves to the bin.
• Scatter chopped onion around – refresh the onion every few days.
• Make a spray using peppermint, eucalyptus or citronella essential oil – use one part essential oil and nine parts water in a spray bottle. Then spray this mixture around the edges of your garden. High-strength peppermint oils are also available as powders which should be sprinkled around the plot.
• Also sprinkle chilli powder, cayenne pepper and cinnamon around as well as spreading lavender and bay tree cuttings around the base. The fermented contents of a bokashi bin are said to be a deterrent as rats dislike the sour smell.
• A niche solution – if you happen to have access to owl feathers then scatter them around your garden.  Rats sense threats easily so feathers from their predators scare them.  
• An obvious point but sometimes overlooked – be vigilant that you never drop any food waste around a composter, bin or food caddy.

With the Green Johanna:

•  Keep temperatures in the bin high by fitting the Insulating Jacket when suitable, adding bokashi bran, and keeping the bin filled and aerated. Hot composting generally discourages rodents because of the heat and the fact that food scraps are quickly broken down. Even though the jacket is not particularly thick, it does seem to offer some kind of deterrent. Members of the GGS team report that from time to time the jacket on their Johanna has been nibbled in places but then the culprit has obviously given up. An allotmenteer once showed us evidence of a badger attack on his Johanna and again, there was some nibbling on the jacket but the culprit hadn’t gone further.
• When setting up the composter, wait until the composting process is well under way before adding cooked food scraps.

The composting environment

• Discourage rats from making a home in your garden or allotment by sealing access under chicken houses, sheds or decking that can provide shelter for them.
• Keep the area well maintained – check for anywhere that rats could burrow under or through.
• If you store bird feed or chicken food in the garden, make sure it is in lidded containers and kept off the ground. Sweep up any fallen birdseed as birds are messy feeders. Put paving slabs under a bird feeder so any fallen seed can be easily swept up.
• Make sure any bins are not overflowing and food caddies are locked tight.
• Maintain drains – rats can come up through poorly maintained drains.
• Keep an eye out during bad weather and flooding as rats are likely to be on the move looking for shelter.
• Rely on rodents’ old enemies – keep a cat or terrier.

With the Green Cone:

• Ensure that the top of the black basket and the bottom lip of the green outer cone are below ground level, so that any odours are filtered out into the surrounding soil.
• Never allow food waste to come higher than the top of the underground basket. Food waste should never reach as high as the Cone itself.
• Press builder’s mesh (available at DIY stores) into the soil of the hole you have dug for the black basket to provide an additional deterrent.
• Add accelerator powder regularly to boost the breakdown process. Aim to use one sachet per month.
• Ensure the Cone is in a sunny spot as the digester relies on solar energy to enable efficient digestion.

What about badgers?  

Master composter Rod Weston (in his book A Gardener’s Guide to Composting Techniques) advises using human (male) urine diluted and sprayed around the plot every four weeks. 

We also read an interesting piece in The Sunday Times when a reader asked for advice on how she could deter the badgers which were wreaking havoc in her garden. Another reader wrote in to suggest: ‘Regularly scent-mark your territory with male human urine’. He added, ‘Yes, I know. But it does work.’

Rod also makes several recommendations, some of which he says are more practical than others (as you’ll see when you read them):

• LED lights triggered by infrared sensors (which are effective, but badgers can get used to them).
• A ‘smelly’ washing line at badger height hung with cloths impregnated with various oils, including citronella, clove, eucalyptus, menthol, juniper berry, wintergreen.
• Scotch bonnet peppers chopped or crushed and scattered on the ground.
• Lion manure.

Of course, it’s difficult to know which measures in particular have been effective; it would be nice to see a dejected rat or badger packing their bags and walking off into the sunset as proof that your strategies have worked, but we’ll just have to be happy with an un-nibbled compost bin.