Do Worms Eat Algae?

Algae is all around us. There are countless different types. We know that there are thousands of upon thousands, possibly even millions! But do worms eat algae as part of their average compost bin? Is algae actually beneficial to a worm’s nutrition?

The answer is yes, earthworms that eat dirt do eat the algae that is found within, along with the different bacteria and fungi. They also eat seaweed, one of the most commonly-known forms of algae.

However, they don’t munch through it like a snack (although worms have mouths, they don’t have teeth so can’t bite – they make a point to absorb the nutrients and to deposit it all back into the soil!

Do worms like to eat algae?

Algae is no different from any other organic decaying food to a worm.

The various kinds of seaweed that can be digested by an earthworm are becoming more and more popular within the composting scene.

Worms like to eat dead and decaying food, which is why they are so happy living in worm composting bins.

Providing you fill the compost bin with the correct material (old fruits and vegetables, their peelings, etc), then an earthworm will happily chow down.

They’ll produce worm castings (i.e. worm poop) that will later feed your vegetation.

Indeed, some choose to directly place the seaweed at the base of the plants, flowers and trees, as a natural fertilizer.

The effects of algae on plant growth have been increasingly promising. It’s proven to be some of the most effective organic matter to use as fertiliser.

Those who choose to maintain worm composting bins have found the stuff to be equally beneficial to the worms, too – and by extension, to their plants.

It contains various kinds of vitamins and nutrients that will only make your little friends healthier and happier.

How should I prepare the algae for the worms in my worm composting bin? 

There are various things to do to algae, depending on its current state and where it is from, before feeding it to the worms and red wigglers in your worm compost bin. 

Freshwater seaweed can be put practically directly into your compost bin, but it is better to start with a little and to see how it affects your pile!

Salt water seaweed will naturally have to be dealt with a little differently.

If you present it to the worms directly from the beach without rinsing it, the salt within it will damage the composting pile by absorbing the liquid.

Your worms will also likely be harmed in the process!

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Due to the fact that worms breathe through their skin, as opposed to lungs as we do, the environment in which they live needs to be damp at all times.

Too much salt could easily dry up their environment and their skin, causing burns and dehydration.

On the other hand, rinsing your seaweed or otherwise it is not enough. Whilst worm compost bins need to be damp, they should never be drenched.

If they find themselves in a very wet area, they will automatically rise to the surface of the ground to ensure their survival.

Naturally, should they be on the surface surrounded by leftover water from the wet algae, they will not be doing their job.

Should they have an escape route from your composting bin, you may also find that they will leave of their own accord.

It is imperative to provide algae to your earthworms that has been treated properly.

A good way of ensuring their safety is by feeding them pre-dried food, or which has dried thoroughly – just be aware of their salt and sodium content as this could decimate your bin.

Is algae dangerous for earthworms? 

Depending on the source, algae can be dangerous to feed to earthworms. You need to be very careful.

Should you have sourced some algae that has washed up onto a beach, or even bought from a shop, you should always look into its source, salt and sodium content .

Should it have come from a polluted part of the ocean, it could be dangerous to your compost, to the worms and to you.

Though worms actually have a very high tolerance to toxins (for example, in this study, earthworms were used to remove metal toxins like arsenic and mercury with a success rate of up to 72%!), it’s still not a good idea to feed potential toxin-containing foods to your earthworms.

Those chemicals may still then end up in your earthworms, your plants, and then even end up in your food. So, even though your worms might be fine, think of the chain of events all the way down the line.

Nearly all of the decaying matter that comes from the organic material that you add to your bin will be consumed by the worms within, including any harsh and/or dangerous chemicals.

So, always be very careful with the food your worms eat, as it might end up on your plate, too.


Worms love algae and are very capable of digesting it properly, but should you come across some and want to use it in your composting bin, always make sure you know where it’s come from.

Otherwise, why not throw seaweed in with other waste for your earthworms to eat?

Get reading our further articles, too, on foods that worms eat to put in your worm farm to keep your compost rich and healthy. Happy vermicomposting!