Rats and Outdoor Trenches

This question comes from Melinda, and pertains to the topic of composting trenches – specifically, whether or not they are prone to invasion by pest animals.

Bentl[e]y, I was wondering if you have had any problems with
rats. we have a canal behind our house and will get rats eating my
garden plants. they like tomatoes and cucumbers. I had a composter a
few years ago but the rats got inside it from underneath. I was
thinking that adding a trench might keep up with our excess waste that
the worms can’t just yet but worried about the rats.

Hi Melinda,
I think I am quite lucky as far as my location goes – for whatever reason we don’t seem to have ANY pest animals, other than the occasional bunny rabbits that munch on our perennials. You can even leave stinky garbage bags sitting out overnight here without any concern that a raccoon or even a dog will tear into it!

I suspect that if the rats are eating your veggies and getting into your composter, there is a reasonable chance they will sniff out the goodies in your trench as well. One of the things I love about the trench system is that it is pretty well odourless (unlike my non-vermi backyard composters) – but Rats and other animals have a much more powerful sense of smell than we do.

You might try “pit composting” and see if they get into that. Simply dig a hole and fill it with food waste & ‘brown’ materials like shredded cardboard etc – then cover it over with soil. If you find that the rats are digging into that, then you won’t have much chance with the trench. If they DON’T seem to detect the pit, perhaps you can try out a small trench.

Hope this helps, Melinda!

I’d definitely be interested to hear if other people have issues with pest animals getting into their composting systems. Please write in or add a comment to this post if you have something you’d like to share!

**For Even More Worm Fun, Sign Up for the RWC E-mail List!**
Previous Post

How Many Worms Is Enough?

Next Post

Killer Catnip


    • Asha
    • July 29, 2008

    I have rats around my area, so vermicomposting in anything that they can access is out of the question. My neighbor who also does vermicomposting, regularly found rat poop near her vermicompost bin and later realized that she had an issue of worms escaping – so obviously the rat was around to get them.
    I have a pit dug where I add only grass clippings and dried leaves – no worms.

    • Bentley
    • July 29, 2008

    Hi Asha,
    Thanks for sharing that!
    I guess the only solution would be to build a worm bin with an enclosed bottom and no other way to get in.
    I bet rats would love to eat worms too.

    • Waneta
    • July 30, 2008

    Rats were the first thing that I thought of when I read the trench article. They moved into my suburban neighborhood a couple of years ago. After years of putting kitchen waste in compost bins, I started vermicomposting indoors last year because of rat infestation of the outdoor bins.

    I do some pit composting when there’s more waste than the Can o’ Worms and the Auxiliary Bins can handle. If it is a small amount of waste well mixed with dirt, and buried under several inches of dirt, the rats will probably leave it alone. If the waste is concentrated (like a bucket full of apples that rotted before I could make applesauce), there will be rat tunnels within a day or so. Some of the waste will even be dug up and left on the surface, although that could have been the resident fox hunting the rats.

    • Letitia
    • July 31, 2008

    This is an idea from one of my uncles who regularly has to fend off rabbits in his garden: he puts down a metal grating on top of the soil and straw at the base of his plants and attaches with wires to a car battery. Voila! An electric fence. This might work for repelling rats if you put the grating on top of the straw above the trench? Anyone willing to try?

    • Bentley
    • July 31, 2008

    Interesting idea, Letitia – thanks for sharing that!

    • Ed Walser
    • August 1, 2008

    I’ve just started an outdoor “above ground trench.” I built it using salvaged bricks for the sides – and – lining the floor of the trench. I too, have had rats in my compost bins. However, they don’t seem to be getting into the trench, which I’ve already loaded with about 400 lb of vegetable waste, straw and topped off with a layer of horse manure. Still too hot for the worms, though. I wish it would finish composting quicker.

    I haven’t had problems with rats or other animals (we have opossums, rats, rabbits, squirrels and foxes) getting in the trench in the past two months. With the loose brick liner, they can’t dig in from the sides and bottom, and they haven’t shown any interest in getting in through the top. If they do, though, I have materials to make a barrier out of hardware cloth and lumber.

    • Bentley
    • August 4, 2008

    Sounds like an interesting set-up, Ed – thanks for sharing.

    • jennifer
    • November 3, 2008

    What area of the country are you located in red worm composting man?

    • Bentley
    • November 4, 2008

    I am located in Southwestern Ontario (Canada)

    • Glennda
    • September 22, 2018

    I just harvested some vermicompost, moved the worms into new bedding and fed them. Two days later the scraps have vanished and only a few worms are left so something got in there I figure and ate both scraps and worms. I have now closed the only opening with duct tape smeared on the outer side with Tanglefoot. I strongly suspect rats and hope the goodness of the Tanglefoot will at least deter them

    • Elizabeth
    • May 1, 2019

    Has anyone tried an ultrasonic rodent repeller, like this: https://www.amazon.com/gp/product/B07F6BB2M7 ?
    I’m wondering if it will repel rats without perturbing the worms.

    • Kirsti
    • March 24, 2020

    To my dismay, my trench is supporting any number of mice or/and other rodents. It is located in the garden beside shed, so they live under shed and go into the trench whenever they feel like it. Of course it is covered with straw and tarp with rocks but that is all the more attractive for them. Any ideas before I abandon the trench? I doubt it is worth the risk of so many rodents near the home… I worked very hard on the trench so this is VERY disappointing!

    • Bentley
    • April 25, 2020

    Hey Kirsti – rodents can be a pain, especially if you are using food scraps or commercial feeds (yard wastes and manure are far less likely to attract them). Others have made some interesting suggestions. Overall the key is to make the system as uninviting as possible. A covered trench left alone for long periods of time is much more inviting than an uncovered system you are constantly disturbing etc. Don’t give up!

    • Kirsti
    • April 28, 2020

    Thanks, Bentley. Yep, I sure did think of giving up my trench… But now that you have offered a new suggestion of manure, I will of course give it a try. We are in a similar area – is there a particular kind of manure I should get from typical store here? Secondly, can I continue to use food scraps, but just add in layers, esp top one of manure? Thank youuu!

    • Bentley
    • April 29, 2020

    Hi Kirsti
    Unfortunately the bagged manure you get from stores isn’t very good. Much of the nutritional value is gone and it can also contain high levels of salts. Something like horse manure that’s been sitting outside for a period of time is far superior (worms will go crazy for it) and in a lot of cases it can actually be obtained for free. As for food wastes – yeah I would say that use of manure and other “living materials” like old rotten leaf litter, rotten straw etc as cover materials would make a a big difference in terms of reducing the odors that attract rodents. You might even try urine – whether from predators (can be purchased) or humans (wink) to see if that deters them. I’ve seen a BIG difference between quiet times of year when I’m not doing much work on the beds and active times of year (not surprisingly, far less rodent activity in beds when I am out there a lot).

    • Kirsti
    • April 29, 2020

    Ok, that is helpful, but that means I would have to ask a farmer for manure then? Any farm animal source ok?)

    • Bentley
    • April 29, 2020

    A local horse stable might be easier to track down and they may be more willing to let you take some off their hands (farmers often spread manure on their fields). It should be some form of bedded manure (ie mixed with things like straw, wood shavings etc), and best to avoid poultry manure. Even without manure, things like grass clippings, mulched leaves – and increased activity, watering etc – should help. Think like a rodent and what you would hate! hahaha 😉

    • Kirsti
    • April 29, 2020

    Thank you, Bentley, for the great tips!

Leave a Reply

Your email address will not be published.

Get Your Free Vermicomposting Guide!

* Join the Red Worm Composting E-Mail List Today *