Can coffee grounds be used to fertilize houseplants? – A PUZZLE

Fertilizing houseplants is an important aspect of houseplant care, and there are many natural fertilizers you may have considered trying. One question many people have is whether coffee grounds can be used to fertilize houseplants.

Can coffee grounds be used to fertilize houseplants? Coffee grounds can be used to fertilize houseplants, but it’s best to compost them first. Applying coffee grounds directly to the underside of houseplants can lead to excessive moisture retention, excessive mold growth, and even plant growth.

Coffee grounds are a very useful source of nutrients that can be used effectively by houseplants and a very cost effective fertilizer. Read on to use them effectively without harming your houseplants.

Why use coffee grounds to fertilize houseplants?

Coffee grounds are a common kitchen scrap, full of nutrients that most people throw away. They are readily available, free, and rich in nitrogen, one of the most important nutrients for healthy plant growth. Using coffee grounds on houseplants is also a great way to reduce household waste.

People have been using coffee grounds in their gardens for years with reasonable success, so it’s only natural that people experiment with using coffee grounds to fertilize houseplants. As we will see, it is certainly something to be aware of, but there are major problems with using it.

What are the best ways to use coffee grounds to fertilize houseplants?

Although some people are tempted to add coffee grounds directly to the soil of their houseplants, this is not recommended and can cause a number of problems. However, there are three great options for your houseplants to benefit from coffee grounds as fertilizer.

1. Use coffee grounds to make compost

By far the best way to use coffee grounds is to compost them. Add all of your used coffee grounds to your compost pile and wait until your compost is ready to use.

Most houseplants come from tropical climates, where they get most of their nutrition from the decaying organic matter produced by the dense vegetation around and on them.

Homemade compost closely mimics this natural process and provides enough nutrients to help your houseplants thrive. The high nitrogen content of the coffee grounds (NPK 2.1-0.3-0.3) is compensated by the other components of the compost you have made.

You can apply this compost when transplanting or you can add a thin layer to the soil or work into the top few inches of soil.

Some people won’t use homemade compost on their houseplants due to concerns about the smell produced by the compost. In my experience, that’s not a problem. Any odor produced dissipates very quickly and can be largely avoided by incorporating the compost into the soil.

There are two things to keep in mind when using homemade compost on your houseplants.

First, over-application of compost can lead to leaf burn and nutrient toxicity symptoms. Add a maximum of 1 inch (2.5 cm) of compost to the pot to prevent this.

Second, because compost is rich in organic matter, it naturally retains water, which can increase the risk of overwatering. Keep this in mind and water it gently to avoid problems.

2. Make liquid fertilizer for indoor coffee trees

While I don’t recommend pouring coffee over the soil of houseplants, you can turn coffee grounds into a compost “tea” that will work well on your houseplants.

There are many different methods for making compost tea, but one of the easiest is to simply add the coffee grounds to a container filled with water and let steep for 1-2 weeks, stirring every few days.

As coffee begins to break down, it releases nutrients into the water and provides a rich breeding ground for beneficial bacteria. You can then strain this liquid through cheesecloth and use it to water your plants.

Not only does this provide a good source of nutrients, but it also adds beneficial bacteria, which can improve the health of the soil and your plants.

ground coffee for fertilizing indoor plantsimage sources

3. Add coffee grounds to potting soil when transplanting

Since coffee grounds are an organic material, they slowly release their nutrients as they break down in the soil. This allows you to use coffee grounds as a slow-release fertilizer when mixed with the potting soil you use for your plants.

Although it may have some issues, depending on the plant it can be a sustainable source of nutrients for up to 6 months. Coffee grounds are one of many natural fertilizers for houseplants, but you need to make sure you use them correctly for best results.

Coffee grounds contain a large amount of nitrogen compared to phosphorus and potassium. Houseplants with relatively higher phosphorus and potassium requirements may not do as well as they should if you only use coffee grounds to fertilize your plants.

There are a few issues with using coffee grounds in potting soil, which I’ll address in the next section.

Problems of Using Coffee Grounds to Fertilize Houseplants

While we’ve discussed some of the ways you can use coffee grounds to fertilize your houseplants, it’s important to take a closer look at the downsides.

Excessive water retention

Coffee grounds are exceptionally good at retaining moisture. Its organic character and fine particles act like a sponge and retain soil moisture. This is a huge downside because the most common problem for most people who care for houseplants is overwatering.

Adding coffee grounds to soil greatly increases the risk of overwatering houseplants, which can be disastrous for plants.

If you use coffee grounds on your houseplants, either directly or as part of compost, you can reduce the risk of overwatering by changing the composition of the soil you use.

Adding more coarse sand or perlite to the potting mix will increase drainage, allowing the soil to dry out more quickly after watering, reducing the risk of overwatering and root rot.

Other options are to use a porous pot and/or a smaller pot. Both of these changes will cause the soil to dry out faster, reducing the risk of overwatering.

Promotes mold growth

It’s more of a problem if you add coffee grounds to the topsoil of your houseplants. Coffee grounds are an ideal breeding ground for fungal organisms, which can lead to fungal diseases in your plants.

It’s especially disappointing when you’re trying to feed your plants and promote their health, only to give them a fungal disease that can do a lot of damage.

This problem can be reduced by ensuring that the coffee grounds are properly incorporated into the soil. Ideally, composting coffee grounds or adding coffee grounds when transplanting will reduce this risk.

fungi in coffee grounds used to fertilize houseplantsMold often grows on coffee grounds that are added to the soil surface of houseplants.

attracts pests

Although coffee grounds may deter some pests, many pests and insects are attracted to the conditions created by coffee grounds in the soil of houseplants.

This once again highlights why adding coffee grounds to the soil surface is not recommended. Using coffee grounds to make compost is by far the best option if you want to use coffee grounds to fertilize houseplants.

Coffee grounds can even inhibit the growth of certain plants.

A number of small-scale studies have shown that coffee grounds added directly to soil can inhibit plant growth, especially in seedlings and young plants. This is thought to be due to the caffeine content of the ground coffee.

There doesn’t seem to be any evidence that using coffee grounds for composting causes the same problem, so again, this seems like the best option for using coffee grounds to fertilize your houseplants.

There are much better alternatives

The bottom line is that using coffee grounds to fertilize houseplants is not ideal. There are much better natural or synthetic options for fertilizing your plants, and you’re probably better off using coffee grounds for your outdoor plants, or using that kitchen scraps in a different way.

Many people can now have their kitchen and garden waste collected separately from the rest of their waste by the municipality. This allows local communities to recycle this organic waste into compost, for use in more suitable environments.


Although you can use coffee grounds to fertilize houseplants, you should avoid the problems that come with it. For most people, I recommend using coffee grounds for your outdoor garden and using alternative options for fertilizing your indoor plants.

If you really want to stick with coffee grounds, you’re much more likely to make compost or compost tea with a positive result.

Read this article to learn more about more natural ways to fertilize your houseplants. Or check out this article to find out which fertilizer I use for almost all of my houseplants.

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