Worms Are Good For Houseplants – Here’s Why

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Before we get started I just want to clarify that I have NO IDEA where worms come from in house plants.

Imagine my surprise when I was repotting my Monstera and there were, like, three full-size earthworms chilling in the bottom of the pot.

They seemed fat and happy so I just left them there.

I'm gonna assume that at some time I ran out of soil and grabbed some from outside, and that had some eggs in it. 

I can't imagine that they were outside in the garden and were like 'hey guys! Fancy climbing into that house and going to live in that funky plant in the bathroom window?'

For one thing, we have frosted glass in the bathroom. They wouldn’t be able to see in.

ANYWAY

Regardless of whether they creep you out or not, worms can be a great addition to house plants. They eat the substrate and then poop out better, more nutritious substrate.

Incredible.

Why are there worms in my house plant soil?

Eggs just…turn up.

It happens in most hobbies that involve living things.

If you’ve ever had an aquarium, you’ve probably accidentally introduced snail eggs into a tank when you added new plants.

In fact, be grateful that it's something as useful as earthworms (millipedes are also great guys to have in your substrate). 

More often than not the creatures we inadvertently introduce to our plants are literal predators like slugs and snails. 

In the words of the great Ian Malcolm, ‘life, uh, finds a way’.

I like to think that worms purposefully make their way to our plants. I mean, it’s safe for them.

Protected from the elements, they’re less likely to dry out or flood (er, theoretically), and they don’t have to worry about blackbirds.

SURE, there’s less space, but I’m not entirely sure what the size of an earthworm’s territory is, or how much they enjoy travelling.

Can you put worms in your indoor plants?

You definitely could, and you could also argue that you’re adding beneficial bugs into your soil, but there are a few things you need to take into consideration:

  • You could potentially be introducing pests and diseases into your home

When you bring your unwitting new pet into your home, presumably he’s gonna be bringing a bit of soil with him. You have no idea what’s in that soil. There could be fungus gnats, bacteria, or even a thrips that’s got lost.

There are ways of getting ‘clean’ worms. You can buy red earthworms from fishing tackle shops, which is probably the best-case scenario for those poor suckers.

  • Is it ethical?

I am a VERY indecisive person that really struggles with what’s right and wrong when it comes to how we treat other animals.

For me, I feel most at ease when I just don’t partake.

That’s why I’m vegan – I don’t know definitively if eating animals is right or wrong so I just don’t.

Is it wrong to keep earthworms inside? I have NO idea. None. Haven’t a clue. So I just won’t.

Having said that, if they find themselves in my plant pots of their own accord, I’m going to keep them.

They seemed fine in my Monstera – moving normally, not thrashing about, everything seemed fine.

If you think I'm weird for caring about a worm's freedoms, I totally understand. 

My brain is an exhausting place to be, hence making the decision to just not do things I find ethically ambiguous.

The best way to use worms for indoor plants

Whilst I wouldn’t advise going out and collecting earthworms to keep in your house plants, there are other types of worms that will live perfectly happily in your soil and will eat fungus gnat larvae for you.

I’m not sure if beneficial nematodes count as worms, but we have them in our terrarium (they just turned up too) and they certainly look like worms.

Not all nematodes are beneficial, but you can buy the correct ones dried on Amazon, add them to your water, and water your plant as normal. 

I have an article on beneficial nematodes here.

I don’t have a problem with fungus gnats (one of the upsides to being a bit of an underwaterer), so I’ve not had to weigh up the ethics of adding nematodes to my plants.

Do worms benefit houseplants?

Yes they do! Worm castings (poo) are called black gold in gardening circles because it’s a very rich fertiliser that’s extremely gentle, so you won’t burn your plant’s roots regardless of how much you use.

If you have worms in your plant’s soil, then those worms are constantly at work, eating decaying matter and pooping out fertiliser, right into your plant’s roots.

I’m not entirely sure whether adding one worm to your plant pot will mean you’ll never have to fertilise it. I’m really not sure of the volume of poop one worm can provide, BUT it’s definitely adding some nutrients back into your soil.

Not only are worm castings nutritious, but they also provide a habitat for beneficial microbes in the soil, that can help the plant grow stronger, faster, and be more resistant to pests and stress.

How to make a wormery

I’ve considered moving my resident earthworms into a wormery a few times, but whenever I come to repot the Monstera, I never think to set one up.

A wormery is a great thing to have – it’s basically a way of getting free worm castings. Not only is this super nutritious for your plants, but it’s a great way of composting your old vegetable scraps. Also, it’s nice knowing that your plants are all fed with fertiliser you made yourself.

At our old house we had compost bin that was FULL of worms, but that wasn’t an actual wormery (or vermicompost bin, to use the technical term). You’ll get compost out, rather than worm castings, which will be more likely to attract fungus gnats if you use it in your plants.

To make a wormery, you need something to put your worms in. A lot of people repurpose bathtubs, because they’re a nice size, plus you can move the worms over to one side and then harvest the castings from the other side, which is harder to do in something tall and rectangular like a compost bin.

You'll need drainage holes in the bottom of whatever you're using. 

A lot of people put a bucket underneath and use whatever liquid leaches out. 

Put a layer of leca or rocks on the bottom, and then a membrane of filter foam or similar (this guy used an old trampoline liner - iconic) then fill your box with coir. 

Add your worms (buy red ones, either online or from a fishing tackle shop - regular earthworms won't work in a wormery because they live deeper in the soil), add some food (kitchen scraps, coffee grounds), and cover with cardboard and shredded paper.

After a while, the coir will have turned into worm castings!

The bonus about using something rectangular like a bath is that you can add food to one half and all the worms will move over to that half, leaving the other side worm-free and ready to harvest.

Final thoughts

Worms can be beneficial to house plants, but you don’t need actual worms – just their poop. You can buy worm castings online, but they’re pretty expensive compared to other fertilisers. A low-cost (and dare I say fun?) option is to create your own vermiculture bin.

Caroline Cocker

Caroline is the founder and writer (and plant keeper) of Planet Houseplant

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