How to Compost Coffee Grounds (for Garden Fertilizer)

Ever wondered why coffee shops give away bags of their used coffee grounds? Turns out, this is an organic material that’s fantastic for the garden in several different ways.

Here’s everything you need to know about how to compost coffee grounds in order to gain maximum benefits from them.

How to Compost Coffee Grounds (for Garden Fertilizer)
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What’s So Great About Coffee Grounds?

How to Compost Coffee Grounds (for Garden Fertilizer)
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The main benefit to using coffee grounds in your garden is that they’re an incredible source of nitrogen. They offer this important nutrient in similar quantities to chicken, cow, and horse manure. However, coffee grounds come without the risk of the pathogens that all animal products come with.

While coffee grounds might be acidic to start with, their acid is water-soluble. Their pH rises to between 6.5 and 6.8 after the brewing and washing process, making them almost pH-neutral. This means that they won’t affect the pH level of your soil, enabling coffee grounds to be used on a variety of different plants.

As an added bonus, any coffee grounds that you use in your garden means less organic waste being sent to a landfill. This is a great opportunity to do some recycling, in a way that your garden will love!

How to Compost Coffee Grounds

How to Compost Coffee Grounds (for Garden Fertilizer)
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There are a couple of different ways in which you can compost coffee grounds for use in your garden.

The most common is by adding them to a compost heap or into a compost bin, but you can also compost them in situ, using them as a soil conditioner.

Adding Coffee Grounds to a Compost Heap

In order for it to actually break down, a compost heap needs to be made up of a 2:1 ratio of green:brown materials. The green materials are those that are rich in nitrogen, meaning that coffee grounds fall under this category.

You can simply throw coffee grounds onto your compost heap, just like you would with anything else. However, in order to keep things balanced, try to also add double the amount of brown materials – your used coffee filters are a good place to start!

After adding the coffee grounds to your compost heap, treat your compost heap as you usually would. Turn it every week or two until it has broken down and is ready to be used.

As they break down, the coffee grounds will help to raise and sustain the temperature of your compost heap. This will destroy any weed seeds and pathogens, giving you healthier compost as an end result!

Try to make sure that coffee grounds don’t make up over 25% of your total compost heap. This is usually pretty easy, but if you’re receiving free coffee grounds from multiple local cafes, then it could end up dominating your compost heap.

How to Compost Coffee Grounds (for Garden Fertilizer)
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Using Coffee Grounds as a Soil Conditioner

Although coffee grounds contain plenty of nitrogen, along with small amounts of phosphorus, potassium, and other micronutrients, these will only become available to your plants as the coffee grounds break down. For this reason, coffee grounds on their own shouldn’t be used as a fertilizer, but they do make a great soil conditioner!

All you need to do is mix a handful or 2 of coffee grounds into the soil around each plant. Use your hands to work it in beneath the surface.

At this stage, it would also be a good idea to apply a nitrogen-rich fertilizer to your plants.

As the coffee grounds break down, they will encourage beneficial microorganisms to grow in the soil. These microorganisms need nitrogen in order to reproduce.

If you don’t provide them with an extra source, they’ll end up using most of the nitrogen in the soil. This will leave your plants lacking in this essential nutrient, because it will take some time before the nitrogen in the coffee grounds is usable.

Once you have added your coffee grounds to the soil, either with or without a fertilizer, you can either leave them to do their thing, or cover the soil with a mulch.

Let’s see this video to know why these people use coffee grounds in their garden:

Can Coffee Grounds Be Used as a Mulch?

Let’s get straight to the point – NO, coffee grounds should NEVER be used as a mulch.

Yes, they may be an organic material and yes, they may provide a slow-releasing source of nitrogen, but they also form an impenetrable layer when they clump together. This then prevents water from reaching the soil around your plants, leaving your plants to dry out.

How to Compost Coffee Grounds (for Garden Fertilizer)
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Can Coffee Grounds Be Used as a Natural Pesticide?

Many gardeners have had success in using coffee grounds as a pesticide, especially against soft-bodied slugs and ants.

However, there are just as many gardeners who have seen those very same pests crossing over coffee ground barriers to reach prized plants.

All of the evidence currently out there in relation to coffee grounds as a pesticide is anecdotal. Still, there’s no saying that it won’t work for you, so give it a try if you have some spare coffee grounds lying around.

Storing Coffee Grounds

As mentioned, so many coffee shops are now advertising their free coffee grounds. Even if they aren’t, you’ll likely find that all of your local coffee shops will happily save their grounds for you – after all, it costs them money to dispose of them!

If you would like to add your coffee grounds to your compost heap but want to wait until you’ve accumulated a sufficient amount, they’re easy to store.

Simply keep them in a large container or plastic bag. You can leave this outside – near your compost heap itself would be ideal.

The coffee grounds won’t go off, and will be ready for use when you actually need them. If you happen to notice any mold forming on your stored coffee grounds, don’t worry, as the composting process will consume these and render it all harmless.

Here are 8 great ways to reuse those old coffee grounds:

Conclusion

Learning how to compost coffee grounds gives you access to an extremely beneficial organic material to use in your garden, and one that won’t need to cost you any money!

Whether you add them to your compost heap or compost the coffee grounds in-situ by using them as a soil conditioner, you’ll be improving the health of your soil and plants, while also doing your part for the environment.

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