Do Compost Worms Eat Coffee Grounds?

The benefits of earthworms in a garden are well-known in the gardening world. Studies show that the presence of earthworms in the soil helps improve water infiltration and aeration, which is ideal for growing plants. On top of that, their castings (excrement) create soil aggregates, and their activity can help reduce compaction. 

So, if worms are beneficial in the garden, they’re probably beneficial for your compost pile, right? Absolutely! Earthworms are a great addition to your compost. This type of composting is known as vermicomposting (composting with worms). As you’d probably imagine, the presence of earthworms offers numerous benefits. 

However, to produce good quality compost, you need to take care of the worms, ensuring the environment doesn’t become inhabitable for the worms. Part of this process is providing a balanced environment, which can be tricky. 

So, since coffee is usually acidic, can compost worms have coffee grounds? Will they even eat them? Keep reading to find out!

Can I Give Compost Worms Coffee Grounds?

While you might be tempted to toss your coffee grounds in the trash, consider adding them to your compost pile. Coffee grounds can be a beneficial addition, whether you use worms for composting or not. 

Some folks even go as far as to call coffee grounds the “perfect food” for worms. The worm’s digestion process is an essential part of your vermicomposting bin, but gritty foods are necessary for this part. Coffee grounds are the perfect addition, as they offer plenty of grit that helps the worms’ gizzards with digestion. 

That said, you’ll need to be careful when adding coffee grounds to your vermicomposting process. Although worms enjoy coffee grounds, too much of them can be an issue. Too much of the grounds can make your composting bin too acidic, potentially burning the worms’ skin. 

Damaged and injured worms won’t help your vermicomposting process, so you need to be cautious when adding coffee grounds to the mix. 

Can Compost Worms Eat Coffee Filters?

Coffee filters are another safe addition to your vermicomposting bin. So, if you’re planning on adding coffee grounds from your cup of coffee, there’s no need to shake the grounds carefully into the container. Instead, toss the entire filter and grounds into the bin!

Used coffee filters serve as bedding for the worms, so adding them to the mix won’t hurt anything. Most bins use shredded newspaper or cardboard as bedding, but you can still toss in used coffee filters, even if you already have different bedding in the bin. 

Moist coffee filters will decompose rather quickly, eventually incorporated into the compost mixture. Dried-out coffee filters take a bit longer to decompose fully, but eventually, they’ll also break down and integrate into the mixture. 

How Much Coffee Can You Feed Worms?

Once you decide to compost used coffee grounds, don’t add a ton of grounds all at once. Instead, set the grounds aside in an indoor bin (if you have one), then add them in safe amounts. Too much of the grounds at once can raise the acidity in the container, which could cause issues for the worms there. 

There’s no exact schedule that dictates when and how much of your coffee grounds you should add. The truth is, it’s different for every home. Some bins are larger than others and have more worms living in them. On top of that, other foods can make acidity levels fluctuate, so it can depend on what other food scraps you add to the bin.

For the most part, you can safely add coffee grounds to the mix when you add other food sources to the bin. For example, let’s say you have scraps left over from breakfast, which include a few grains and fruit pieces, and the grounds from your cup of coffee.

Before you add the grounds to your vermicomposting bin, mix them with the other scraps you’ll add to the container. Then, add the mixture to the bin. Make sure the coffee grounds don’t make up more than a small portion of the entire scraps you’re adding. 

Additionally, you might not feed your composting worms every day, so don’t add coffee grounds to the bin if you’re not feeding the worms. 

When you add coffee grounds, pay attention to how the bin smells – this can tell you a bit about the acidity in the bin. If the bin smells similar to vinegar, there’s a good chance the bin is becoming too acidic. 

What Should I Do If I Add Too Much Coffee Grounds To My Vermicomposting Bin?

If you add a large amount of coffee grounds to your vermicomposting bin, you could make the bin too acidic. This can create an unpleasant habitat for the worms in the container, so making the proper adjustments is essential. 

Carefully sifting out the coffee grounds in the bin is probably out of the picture, so don’t try to remove the grounds. Test the bedding using a pH test strip to check the acidity levels. The worms in your composting bin usually thrive in an environment with a pH between 6.0 and 8.0. 

If the environment has a pH lower than 6.0, add a few crushed eggshells to the mix. The eggshells will help neutralize the acidity, in turn balancing out the excessive coffee grounds. 

Where Can I Get Coffee Grounds?

Check in with a local coffee shop if you’re not a coffee drinker but want to add grounds to your compost pile. These shops generate large amounts of grounds but usually, just toss them out, and you might be able to get the grounds for use in your compost pile. 

Pros And Cons Of Adding Coffee Grounds To Vermicomposting Bins

Although coffee grounds are an excellent addition to your composting bin, it’s possible to add too much of a good thing. It’s all about balance – as long as you don’t go overboard, your composting bin and the worms in it should be fine. 

Many worm farmers have a love/hate relationship with coffee grounds and their vermicomposting bins. While the benefits are extensive, the potential drawbacks can be hard to work with. If you’re considering adding coffee grounds to your vermicomposting bin, here are a few things to consider:

Pros Of Coffee Grounds In Vermicomposting 

Coffee grounds can be the perfect addition to your vermicomposting bin. A few of the benefits of adding coffee grounds to the mix include:

  • They can help increase the temperature of the worm farm in cooler months, helping you regulate the temperature of the bin without too much hassle. 
  • They serve as a natural pesticide that deters many insects. 
  • The grounds hold water well, which is ideal for the environment, as worms need moisture to breathe.
  • Each particle of coffee grounds is tiny, which is ideal for the worms’ consumption, as they don’t have any teeth. 
  • The grounds offer grit that helps the worms digest food in their gut. 

Cons Of Coffee Grounds In Vermicomposting

On the flip side, adding coffee grounds to your vermicomposting bin can be a hassle. Here are a few potential drawbacks to consider:

  • The boiling water you use to prepare your coffee makes the grounds sterile and less appealing to the worms. 
  • While the grounds can help regulate the bin’s temperature in the winter, they can make it too hot in the summer, potentially killing the worms. 
  • They take quite a while to rot in comparison to other foods. 
  • The grounds are prone to drying out, which can create a crust. 
  • The tiny particles may compact, forming a sizeable anaerobic clump in the compost pile. 
  • The acidity of the grounds can make the environment too acidic for the worms, so you need to monitor the pH in the bin closely.