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Are Coffee Grounds a Good Fertilizer? (2023 Guide)

By: Heather

are coffee grounds a good fertilizer?

Looking for a simple and cost-effective way to give your plants a boost? Look no further than your morning cup of coffee!

That’s right, as a fellow coffee and plant lover myself, I was thrilled when I learned that I can use my leftover coffee grounds as a natural and effective fertilizer that can help my plants thrive. 

However, with so many differing opinions and conflicting information out there on this topic, it can be hard to know whether or not coffee grounds are actually a good choice for your garden. I decided to set out on a mission to weed out facts from fiction.

In this post, I’ll take a closer look at the key benefits and potential drawbacks of using coffee grounds as a fertilizer, and help you decide if this common household waste is the perfect addition to your planting routine. So grab a cup of joe and let’s dive in!

In this Guide You’ll Learn:

  • Benefits of using coffee grounds as fertilizer
  • Potential drawbacks of using coffee grounds as fertilizer
  • How to use coffee grounds as fertilizer
  • And Much More…!

What Are The Benefits of Using Coffee Grounds as Fertilizer?

Coffee grounds are a preferred fertilizer among gardeners since they offer a variety of advantages.  Below we’ve listed out a few key benefits.

Rich in Nutrients 

Your free coffee grounds conveniently contain essential nutrients for plant growth — including nitrogen, potassium, phosphorus and other micronutrients like magnesium, copper, and zinc. These nutrients are essential for plant growth and are often lacking in many soils.  While the exact proportions for each nutrient can vary, when added to soil, the coffee grounds start decomposing and gradually release these nutrients over time acting as a slow-release fertilizer.

Organic Matter

Coffee grounds are a good source of organic matter, which is important for healthy soil and plant growth. Organic materials give soil a crumbly texture which enhances soil structure; this increases the soil’s capacity to hold onto moisture, oxygen, and nutrients.  Additionally, a healthy soil structure encourages the growth of roots, which ultimately benefits plant growth.

pH Balance 

Coffee grounds are naturally acidic with a pH level of around 6.5. Their acidity can help to lower the pH level of alkaline soils. Many plants prefer a slightly acidic soil pH, and coffee grounds can help to create a more favorable growing environment for these plants. I’ll cover some risks with this below as well, depending on your plant.

Microbial activity

Coffee grounds can increase the microbial activity in the soil, which is essential for breaking down organic matter and making nutrients available to plants. Beneficial microbes can also help to protect plants from soil-borne diseases.

Water Retention

Coffee grounds can help to improve soil structure, thereby increasing water retention. This is crucial for sandy soils in particular because they tend to dry up quickly.

Pest Control

Coffee grounds have been found to repel common garden pests such as slugs and snails. This is thought to be caused by coffee’s caffeine content, which is toxic to these bugs. You might be able to stop damage from these pests by scattering coffee grinds around your plants.

With all these benefits, you can see that  coffee grounds can be an amazing natural fertilizer for your garden (indoor or outdoor!). That being said, it’s important to use them carefully and in moderation as they can have some downsides if used improperly. We’ll examine some of these potential problems in coffee grounds as fertilizer in this next section.

Read More >> How long does it Take Fertilizer to Work?

What are Potential Drawbacks of using Coffee Grounds as Fertilizer?

While I am personally a fan of using coffee grounds as a fertilizer for my plants, I advise it with some caution. There are some drawbacks to using it but you just have to be aware and careful of when to use it appropriately. Check it out:

High acidity levels that could harm certain plants

Coffee grounds have a pH between 4.5 to 6.0, which is mildly acidic.  The pH requirements of your plants should be taken into account if you intend to use coffee grounds as fertilizer because some plants are sensitive to acidic soil. For instance, while some plants, like azaleas and blueberries, do well in acidic soil, most plants need a pH range between 6.0 and 7.0.

Excessive usage of coffee grounds as a fertilizer can result in the soil’s pH being overly acidic, which can impede plant growth and potentially harm the roots.

Also, excessive amounts of the caffeine, which is included in coffee grounds, can be poisonous to plants since some plants are sensitive to it.

Therefore, it is important to use coffee grounds as a fertilizer in moderation and you can consider mixing them with other compost materials to balance out the pH level.

Risk of mold growth if not used properly

Coffee grounds have high moisture content and can create the perfect environment for mold growth.

To prevent mold from forming, you can mix the coffee grounds with other organic matter such as leaves or grass clippings, and avoid leaving the mix in a moist, compacted pile (spread it out!) 

Finally, if you spot any signs of mold growth on your coffee grounds, I would advise that you discard them rather than use them on your plants!

Can attract unwanted pests if not used in moderation

This bit is more relevant for your outdoor garden.

Coffee grounds can help repel some pests, such as slugs and snails. But be careful because if you use excessively, coffee grounds can attract other unwelcome pests. For example if you have too much coffee grounds in your compost pile, you may get unwanted growth of fruit flies. Too much coffee grounds could also produce a pungent odor, drawing pests like rodents or other animals to your garden.

As you can see, while coffee grounds can be a great natural fertilizer for your garden with tons of benefits, it’s important to use them carefully and in moderation to avoid any of the potential downsides.

By using them responsibly, you can enjoy the benefits of this natural and nutrient-rich fertilizer (did I mention free?) while avoiding any negative side effects.

How to use Coffee Grounds as Fertilizer?

You should be cautious and responsible while using coffee grinds as fertilizer for your plants to prevent any potential side effects. Here are some tips and pointers to consider:

Compost your coffee grounds to reduce acidity levels

As I previously noted, coffee grounds can be highly acidic, which can be detrimental to some plants. I advise composting your coffee grinds before using them in your garden to lower the acidity levels. I would encourage you to learn more about what composting is and its advantages. Coffee grinds are broken down via composting, and enables the pH levels to stabilize over time.

Read More >> How to Store Compost (3 Methods)

Check out this video that breaks down the impact of pH levels on your plants, how you can measure pH levels of your plant soil easily and on a budget:

By composting your coffee grounds, you’ll also be creating a nutrient-rich compost that will help enhance the health of your soil and plants!

Add coffee grounds to your compost mix along with carbon-rich materials like dry leaves or newspaper bits. An ideal compost pile should contain an equal mixture of leaves, grass clippings, and nitrogen-rich materials like coffee grounds.

Mix coffee grounds with other organic matter

To prevent issues such as mold, mix your coffee grounds with other organic matter like leaves or grass clippings before applying them to your garden. This will create a soil environment that has improved structure, is well balanced and rich with nutrients, ultimately helping your plants grow and thrive!

Apply coffee grounds in moderation

Although coffee grounds can be excellent for your garden, try to use them in moderation to aprevent over-fertilizing. For example, too much nitrogen can cause your plants to grow too quickly, resulting in weaker stems and foliage. I would recommend that you try to keep coffee grounds to no more than 25% of your soil or compost composition.

By following these tips and guidelines, you can use coffee grounds as a natural and effective fertilizer for your garden while avoiding any potential negative effects.

So next time you’re brewing a fresh pot of coffee, don’t throw away those used grounds – save them for your garden and watch your plants thrive!

Read More >> How to make Fertilizer from Kitchen Waste?

My Final Thoughts on Coffee Grounds as a Good Fertilizer

In conclusion, coffee grounds can be a great fertilizer for your garden, as they are rich in nitrogen and other essential nutrients, can improve soil structure, and attract beneficial soil organisms while repelling common garden pests.

However, it’s important to be aware of the potential downsides, including high acidity levels, risk of mold growth, and the potential to attract unwanted pests if used in excess.

To make the most of coffee grounds as a fertilizer, we recommend composting them to reduce acidity levels, mixing them with other organic matter, and using them in moderation. By following these guidelines, you can provide your plants with a natural and effective source of nutrition without risking any negative side effects.

So, if you’re a coffee lover and a gardening enthusiast, I encourage you to experiment with using coffee grounds in your garden. Just be sure to do so carefully and with moderation to ensure the best possible results for your plants.

So next time you’re brewing a fresh pot of coffee, don’t throw away those used grounds – save them for your garden and watch your plants thrive!

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