Are Coffee Grounds Good For Plants? (10 Pros and Cons)

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There are many uses for coffee grounds, but did you know: you can compost coffee and use it in your garden?

A lot of gardeners use coffee to help their plants grow, but they use coffee carefully. Like other uses for coffee, composting your grounds should be done in the right conditions with the right knowledge.

Here are the top pros and cons to using coffee grounds, and whether, in the end, they’re good for your plants.

5 Pros of Using Coffee Grounds in Your Garden

Coffee grounds are the waste that you throw away after brewing a cup of coffee. Instead of wasting this material, coffee shops will happily give their grounds to customers for use in the customers’ gardens. If you brew your own coffee at home, you can take the grounds right out to your backyard. Here are five of the biggest pros to adding coffee grounds to your garden.

1. It Deters Certain Animals

One of the most common reasons why people use coffee grounds in their gardens is to chase away animals that might try to eat the plants or otherwise cause harm. A lot of people find that coffee grounds are a deterrent against snails, slugs, and cats. These animals are a big problem for gardens because they eat the foliage and cause plants to deteriorate.

It’s believed that there’s something about the taste and smell of coffee grounds that stops certain animals in their tracks. When it comes to snails and slugs, the grainy texture of coffee grounds also acts as a physical barrier that these animals can’t cross.

When it comes to cats, the main problem is that they use gardens as litter and tend to poop or spray everywhere. It’s very frustrating for gardeners, especially if they have neighbor’s cats coming over to the garden and they don’t even own the cat themselves. Not only does the waste ruin hard work, but cat droppings and urine can cause harm if they’re ingested. Cat waste can even cause blindness, so gardeners understandably do not want this anywhere near their plants.

To combat these animals, pour your coffee grounds along the top layer of the soil you have, or put them in piles surrounding your plants. Cats are also deterred by the smell, and they’ll likely stop visiting your garden uninvited.

2. It Makes Great Mulch

Coffee can be used as mulch if mixed with shredded leaves, vegetables, and other organic materials. If you mix all this together and put it on the top of your soil, it helps prevent evaporation so your soil will not lose as much moisture. In the winter, mulch helps soil retain heat, and in the summer, it helps soil remain cool.

On top of these benefits, adding coffee grounds to your homemade mulch inhibits the growth of weeds. This is because weeds won’t be able to get into the soil as easily with mulch acting as a physical barrier. Mulch also doesn’t let much light in, preventing different kinds of weeds from germinating deep within the soil.

It’s perfectly fine to use coffee grounds as mulch. However, you should not use coffee grounds alone. Always mix them with some type of other organic material; if coffee grounds are used by themselves, they can prevent soil from receiving any water at all, which leads to a dry garden.



3. It’s a Slow-Release Fertilizer

Using coffee grounds as fertilizer can be highly effective because grounds release nutrients very slowly. On top of micronutrients, used coffee grounds also contain:

  • Potassium
  • Phosphorous
  • A decent amount of nitrogen

All of these are essential nutrients for the health of your plants. By adding coffee grounds to your soil, you’ll be giving plants the nutrients they need. Due to the slow-release process, the roots of your plants won’t get nutrients right away, but instead, will receive them slowly as the grounds break down. All of this makes coffee grounds an excellent gradual fertilizer.

4. It Supports the Worm Population

According to many gardeners, worms actually love eating coffee grounds as food. Using coffee grounds in your garden can lead to an increase in the worm population of your soil, which is vital for the health of plant roots. Worms also aid in breaking down compost and offer several other benefits to gardens. Adding coffee grounds will keep the worms in your garden happy–which in turn leads to a happy gardener.

5. It Improves the Drainage of Your Soil

Coffee grounds are an organic material, and organic materials help improve the quality of your soil. As you slowly increase the amount of organic material, this ensures that water doesn’t collect around the roots of your plants. Too much water causes rotting and prevents plants from growing properly, so adding some coffee grounds every once in a while is a great way to boost the amount of organic material in your soil–just make sure you mix your grounds with the soil very well.

5 Cons of Using Coffee Grounds in Your Garden

There are many benefits to adding coffee grounds to your garden and using coffee grounds in compost. However, it’s important to be aware that there are some potential negatives to using coffee grounds as well. Take a look at the top 5 cons of using coffee grounds, and decide whether it’s useful in your situation to put them in your garden.

1. In Large Quantities, Coffee Grounds are Harmful to Dogs

Many gardeners love using coffee grounds because grounds keep away common pests such as cats and slugs. However, coffee grounds may be harmful to other kinds of animals. If you’re a dog owner or dog lover, be aware that coffee grounds are harmful if you add them to your garden in large quantities.

Dogs tend to sniff around and eat anything they think smells and looks tasty. However, coffee grounds are toxic to dogs if ingested, and the caffeine coffee contains can especially be harmful. A small amount of grounds sprinkled in your garden shouldn’t be a problem–it would take a pretty large amount to cause harm. However, consuming coffee grounds has resulted in dog fatalities. If you love having your dog with you as you garden, it’s likely not worth the risk as you don’t want to cause any harm to your pet.

2. It May Inhibit Plans from Growing

Coffee grounds do contain residual caffeine, and this caffeine inhibits both seedlings and mature plants from growing as they should. If you have young plants in particular or have just put in seeds, it’s best to not have coffee grounds anywhere near these. Coffee can destroy the roots of new plants, which leads to their demise even before they’re able to grow much.

The same thing can happen to mature plants, as well. Caffeine may prevent seedlings from becoming well-established and can also lead to negative effects on plants that have actually had time to grow. Once roots take hold, the caffeine from coffee grounds may restrict further growth, leading to the plant becoming stunted. While grounds aren’t as likely to be harmful in this case as with seedlings, it’s still worthwhile to consider–especially if you have mature plants in your garden and don’t want to risk them.

In fact, this is one of the reasons why coffee plants grow so well. The caffeine they have prevents nearby plants from growing as well, so coffee plants easily take over and have all the nutrition and sunlight they need. You won’t see many other plants growing on coffee farms.

3. The Antibacterial Properties May Kill Good Bacteria

Soil contains many different types of good bacteria, which keep diseases and pests from infiltrating your garden. When it comes to the health of your soil, antibacterial properties can lead to big problems–and coffee contains antibacterial properties. While these properties are in general beneficial, they may wreak havoc on your soil.

Introducing antibacterial properties to your garden may lead to killing off all the good bacteria, which in turn leads to the soil becoming more vulnerable to diseases and pests in the future. Good bacteria disappearing can also change the soil’s natural biodiversity. This causes all kinds of problems for earthworms and other types of creatures that naturally reside–and help–your soil. Keep in mind that coffee grounds could cause problems in your garden in the future.

4. Coffee Grounds Can Form A Dense Barrier

Small particles make up coffee grounds. These particles, when they dry out, become tightly compacted together and form a solid barrier. It’s easy to overdo it by adding coffee grounds to your garden and ending up with a texture similar to clay. This clay texture does not provide plants the nutrition or hydration they need and leads to a stunted garden.

When coffee grounds become too dense, this creates a physical barrier on top of your soil. Water will not penetrate through, and plants will wither. This is why it’s crucial to add coffee grounds in a specific manner, rather than throwing them on top of everything.

5. Coffee Could Degrade Your Soil

Another reason to consider is this: Coffee is caffeinated. Several studies have shown that caffeine can suppress the growth of other plants. This isn’t true for all plants but something to keep in mind when you’re a beginner gardener and may not know yet what to mix and match.

Composting Coffee Grounds

Adding your used coffee grounds to compost is an excellent way to save grounds from a landfill and instead reuse them. It’s perfectly safe and okay to add coffee grounds to your compost–in fact, they actually provide a unique and significant benefit: they add nitrogen to the rest of your compost. This provides plants with essential nutrients and encourages healthy growth.

If you’re wondering how to add coffee grounds to your compost, it’s easy: just toss them onto the compost pile–used coffee filter included–and that’s it. Just make sure you have brown compost materials, as coffee grounds are green waste, and you need a mix of the two types.

What Benefits Can Coffee Grounds Bring to Plants?

Your indoor plants need nutrients to thrive, just like people. Many choose to compost their own rich, organic soil for garden beds and houseplants.

Using coffee grounds in your compost or mixed into your indoor soil mix is the best way to deliver nitrogen, micronutrients, and retain water within the soil.

Many houseplants require a good amount of water. These are the plants that coffee grounds are going to benefit most.

Because coffee grounds hold onto moisture so well, they act as a slow water delivery system to the roots. This means less frequent watering on your part.

Tips for Using Coffee Grounds in Houseplants

Dry plants such as succulents require less water to thrive. Adding coffee grounds to these types of plants should be avoided, as it will negatively impact your plant within a few days by over-hydrating.

You will have to be careful with which plants you add coffee grounds to because different plants require different moisture levels.

Also, do not add pure coffee grounds directly to the soil as you would fertilizer. Too many grounds are not good for the plants due to moisture retention.

This way, the moisture levels may even cause mold growth. It can also lead to overwatering of the plant and pH imbalance from the natural acidity of the coffee grounds.

Instead, mix your coffee grounds into your indoor plant soil and aerate with your hands.

Some plants, such as the African Violet, prefer acidic soil optimal growth. Others do not so be mindful about how many grounds are going into each plant’s soil.

Two Easy Ways to Use of Using Coffee Grounds in Plants

There are two best practices to integrate your used coffee grounds into the soil. Follow the way the best suits you and the types of plants you have.

Composting

Folks who already have a compost pile will know the value of making your own rich soil or fertilizer.

Composting your used coffee ground will help you to get the most out of your soil by adding even more important nutrients.

For those who do not already compost, this may seem like a daunting project. In reality, composting is very simple and only requires a few rules.

However, if you do not compost effectively, the materials will rot and can attract invasive critters.

Here is how to compost your coffee grounds effectively:

  • Only compost “greens” and “browns” as a rule of thumb. Greens are items high in nitrogen such as eggshells, coffee grounds, or produce trimmings. Browns are items such as paper or raked autumn leaves. Use a 3:1 ratio of browns and greens.
  • Allow the compost to break down in a covered bin in the kitchen or pile in your backyard.
  • Once the compost has broken down, you can add this mixture into your potting soil before using it on your houseplants.

You can also throw your used unbleached coffee filters into the compost bin!

This way, all of the nutrients are properly extracted from the coffee grounds and into the soil for the healthiest environment for plants.

Potting Soil Integration

If composting isn’t your thing, that’s okay. Instead, you can mix the coffee grounds directly into your potting soil.

Plants need a very balanced environment and each plant has different needs.

To integrate the coffee grounds with the soil, add your grounds to a bag of potting soil and loosely mix with your hands.

The more coffee grounds you add, the more moisture and acidity the soil will have.

Since adding coffee grounds means adding moisture to your soil, you may need to compensate in other ways. For example, you can balance out the moisture by adding more sand to the potting soil for better drainage.

If any of your houseplants happen to be succulents or cacti, they may not thrive in an environment with added moisture.

Home gardening is all about balancing the moisture and nutrients, so pay close attention to how each plant reacts to your new nutritious soil.

Caffeinate Your Plants

It’s safe to say that used coffee grounds (and natural paper filters!) are good for adding to your plants.

They add nitrogen, acidity, and moisture retention right into your plants, perfect for houseplants that require lots of moisture or acidity.

There are two ways to integrate coffee grounds into your soil; either by composting or by mixing them into your potting soil.

Composting will bring out more healthy nutrients over a longer period while mixing it still offers similar nutritional benefits to your plants.

Coffee is not only great for your morning routine but for your planting routine, too!

TLDR: Are Coffee Grounds Good For Plants?

Coffee grounds can be very beneficial for your plants–depending on how you implement them. For a long time, gardeners have added coffee grounds to their gardens as it keeps certain pests away and helps to improve the soil. However, it’s important to only use coffee grounds in specific situations and be mindful of how you are adding them in.

Make sure you mix grounds with other types of organic materials and use a little bit here and there. Too much may stunt the growth of your plants, and direct application can be harmful due to the high level of caffeine that remains in the coffee. Sprinkle grounds around and mix them with other materials to ensure you’re using them correctly.

The ultimate lesson is: Be careful with how you use your coffee grounds. It’s essential not to add a lot of them directly on top of your soil. Not only does this cause a clay material to form and inhibits plants from getting water, but it also stunts plant growth and is toxic to certain animals such as dogs. Whether you use coffee grounds in your garden may simply come down to what type of pet you have (or what type of animal tends to visit your garden).

Adding a small amount of coffee grounds may improve your soil and compost pile. The rule of thumb is to follow what’s known as the 20% rule: always add coffee grounds with other organic materials, in 1 part grounds to 4 parts other materials.

Mixing your coffee grounds this way–not using them directly–can, in the end, be beneficial to your garden. Just keep in mind that in many cases, it can be harmful to use too much of a good thing.

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