There’s a lot of talk in the houseplant world about natural remedies and pest repellents that you should be using. One that crops up a lot is using coffee grounds in and on your houseplant’s soil. You might be surprised to learn that coffee grounds can be a really beneficial tool when looking after your houseplants and is a great way to turn kitchen waste into something useful.
If you’re a coffee drinker you’ll likely be aware of what coffee grounds are but just so that we’re all on the same page, coffee grounds are what you’re left with after ground coffee beans have been extracted with water.
In this article we will be going through the different benefits coffee grounds can have for your houseplants, how to use them and all of the tips we have a long the way.
The benefits of using coffee grounds for your houseplants
It can be a great soil supplement
Coffee grounds contain an abundance of nutrients and micronutrients including potassium, calcium and magnesium. This is why it’s so beneficial to your houseplants as a way to turn waste into nutrients for your plants.
These nutrients will aid your houseplants in their development, helping them to grow bigger and stronger new leaves, stems and flowers. Without the right amount or balance of nutrients, your plant can slow down the rate of new growth as well as develop a range of issues including brown and yellow leaves.
So if you’re looking for a cheap and easy way to boost the nutrients in your houseplant’s soil, coffee grounds can be a great way to do this!
Coffee grounds can be a pest deterrent
There are mixed views on using coffee grounds as a pest deterrent as they can actually attract more pests to your plants. This is why we strongly recommend not adding a large amount of coffee grounds to the top of the pot and instead mixing it in.
When used in the right way it can be good at deterring pests from your plant which can help to stop issues such as brown and yellow spots and over time can prevent pests from killing your plant!
How to use coffee grounds for houseplants
Mixing coffee grounds into your houseplants’ soil
When you are repotting your soil anyway, it can be a really great time to add in some coffee grounds. They are a relatively slow release fertilizer which can provide nutrients to your houseplant for up to around 6 months.
How much coffee grounds you add depends on the size of the plant (and therefore the size of the pot) but we recommend for an average-sized plant around 5 heaped tablespoons.
It is also a good idea to test it out by adding only a very small amount to see how your plant reacts. You can then slowly increase the amount if it seems to be working well for that plant.
Top dressing the soil with coffee grounds
Another way of adding coffee grounds to your houseplants’ soil is by adding it as a top layer on the soil. Whilst this is a quicker and mess-free way of doing it, it’s actually less beneficial than mixing it into the soil. This is because coffee grounds are great at retaining moisture so this can create a moist layer which is the ideal spot for fungus gnats to thrive in.
Make compost with your coffee grounds
Another great way to utilize the coffee grounds for your houseplants is by making compost. Add all of your coffee grounds to a compost pile and wait for it to be ready. The benefit of composting your grounds is that it emulates the natural process of nutrition that your houseplants would use when growing in their native environment.
Another benefit of using composted coffee grounds is that the nutrient level will be more balanced from other things you have added to the compost pile. This creates a much better fertilizer for your plants compared to just using coffee grounds.
Pros of using coffee grounds as a fertilizer for your plants
It’s cheap (well, basically free)
The great thing about using your old coffee grounds is that it’s a free way of fertilizing your plants. If you’re a regular coffee drinker then this would have simply gone into the bin and by using it as a fertilizer, it means you’re getting even more value out of your coffee beans.
If you don’t regularly drink coffee, then another alternative could be asking coffee shops for their left over coffee grounds. Most of the time they are happy to give them away to you for free.
It’s environmentally friendly
Using coffee grounds in your houseplants’ soil is also a really great environmentally friendly option. You are preventing the coffee grounds from going into landfill and reducing your overall waste output.
Alongside, this you’re not buying commercially made fertilizers which can often be a lot more damaging to the environment.
Cons of using coffee grounds as a fertilizer for your plants
It retains a lot of moisture
Whilst this can be a benefit for plants that like to have moist soil, it’s often a disadvantage of adding coffee grounds into the soil for a few reasons.
Firstly, moisture can create a nice home for pests to thrive which is obviously an issue for your plant’s overall health. Fungus gnats in particular will love a moist spot but it can also be appealing to mealybugs too.
But it’s not just pests that make coffee grounds’ moisture retention an issue as root rot needs to be considered too. When coffee grounds are added to the potting mix, it means it often takes a little longer for it to fully dry out. This can cause stress to the root system and also make overwatering a lot easier and more damaging to do.
Can result in fungal growth
If you’re adding a top layer of coffee grounds to the soil then this can also be the ideal place for fungal growth to develop. This is because that layer of grounds will likely stay quite moist. You may start to notice in winter that fungus may start to appear on top of the soil as it thrives in cold, damp environments.
This can be a real issue with top dressing and is one of the reasons we recommend mixing the coffee grounds into the soil if you do choose to add them to your plants’ potting mix.
It’s not suitable for all plants
Be careful when adding coffee grounds to the soil of your houseplants because it’s not suitable for all plants. You should avoid adding it to plants that are less than 1 year old as well as seedlings and fresh cuttings.
We hope that our guide to using coffee grounds in the soil of your houseplants has been useful. Whilst there are several benefits in doing so, we don’t always recommend it as a method because there are quite a few downsides too. Yes, coffee grounds are a great natural fertilizer but in our opinion, we have had a lot of success using other methods of fertilization in comparison to coffee grounds.
If you do choose to add it to the soil, we highly recommend mixing it in rather than adding one layer at the top. This can go a long way to mitigating some of the issues with using it and allows you to reap the benefits instead.
As with any changes, it’s important that you monitor your plant’s health closely in the weeks following the addition of the coffee grounds to ensure you spot any issues early. If there are problems, replace the soil with fresh potting mix immediately.
Written by Billy Dawson