Did you know that one of the easiest and least expensive ways to fertilize nearly all common houseplants is by using leftover coffee and coffee grounds?
It’s true! Although most gardeners have heard about the many benefits spent coffee grounds can have for their vegetable plants and flowers outdoors – as it turns out – they can also be used with big success to give indoor houseplants the power they need to thrive. And so can any leftover coffee that might be in your coffee pot too!
Coffee grounds and brewed coffee are rich in the essential nutrients that most houseplants need to grow strong and healthy. Not only do they contain trace amounts of phosphorous, magnesium, potassium and calcium – all key for plant healthy and vitality – they also contain nitrogen, which is crucial for overall plant growth.
Nitrogen actually plays a significant role for a large majority of common houseplants. For starters, it aids in the development of stems and leaves. But even more importantly, it also powers the critical process of photosynthesis, which allows plants to convert light into energy to fuel their growth.
But although coffee grounds and leftover coffee can be the perfect fertilizer for your houseplants – as you will see below, knowing how to use them in just the right way is the real key to success!
How To Use Coffee Grounds & Coffee To Fertilize Houseplants
Coffee & Acidity
One of the most common misconceptions about coffee grounds or leftover brewed coffee is that they are highly acidic and could harm plants by making the soil too acidic.
While this may be true for fresh coffee grounds, used coffee grounds are a different story. Once hot water has run through them during brewing, the acidity level drops significantly. Spent coffee grounds typically have a neutral pH of around 6.7 to 6.8, which is safe and ideal for most plants.
One thing you don’t want to do is use fresh coffee grounds for fertilizing house plants. They can and will turn the soil to a more acidic state. But spent coffee grounds and brewed coffee are a different story. Used in moderation, they are both safe and effective for fertilizing houseplants.
The Importance of Moderation – How To Use Coffee Grounds & Coffee To Fertilize Houseplants
While coffee grounds are full of nutrients, it’s important to know that too much of a good thing can be harmful.
Overloading your plants with too many coffee grounds or undiluted coffee can actually overwhelm them. When this happens, it can lead to problems such as over-fertilizing plants, or creating soil that is far too moist.
Coffee grounds retain moisture exceptionally well. While this might sound like a benefit, it can actually pose a risk to your plants. If too many coffee grounds are placed directly on the surface of the soil, they can create a layer that traps too much moisture around the roots.
This can lead to waterlogged conditions, preventing the roots from properly absorbing nutrients. When there is too much moisture, the roots can swell excessively. Unfortunately, that then causes the plant to yellow, and eventually, the roots rot away.
So what is the easiest way to avoid these issues? The answer is to create a weak fertilizing tea from the leftover grounds or coffee. This allows you to provide a gentle and controlled source of nutrients to your plants – all without the worry of overpowering plants, or water-logging your soil!
How To Make Coffee Fertilizer Tea – How To Use Coffee Grounds & Coffee To Fertilize Houseplants
Creating a coffee tea is a simple and effective way to use coffee grounds and leftover brewed coffee without risking harm to your houseplants. There are two main methods for making this fertilizer tea.
The first method involves using leftover brewed coffee. Because brewed coffee at full strength is too nutrient-rich for most houseplants, it needs to be diluted before use. Mix one part brewed coffee with four parts water to create a milder solution that won’t overwhelm plants. Always allow the solution to cool before using it to water your plants.
The second method uses spent coffee grounds. After brewing your morning coffee, save the used grounds and reuse them to make a weak second batch of coffee. Simply leave the grounds in your coffee maker and run water through them again to produce a diluted liquid.
This weaker coffee is ideal for houseplants, as it provides a gentle nutrient boost without the risk of over-fertilization. Once your coffee tea is ready, use it to water your houseplants every seven to ten days.
This frequency provides a steady supply of nutrients without overloading the plants. Avoid using coffee tea more often than this, as excessive fertilization can harm your plants instead of helping them.
Using The Grounds Of Coffee To Fertilize Houseplants
You can also use the grounds directly in the soil with most common houseplants. But it should be done so very lightly and only at a frequency of once every month or two. For this, simply mix one teaspoon of grounds into the soil for every 2 quarts of soil in your pot.
When fertilizing with this method, it is best to mix in the grounds in the first inch or so of soil to help it blend in.
Houseplants You Can Fertilize With Coffee – And A Few You Shouldn’t
So which houseplants are good with coffee fertilizing? Acid loving plants such as African violets, Christmas cactus, Jade plants, Philodendrons and ferns all do well with coffee fertilizing. Spider plants, pothos and peace lilies along with most herbs also do very well with coffee power.
Some houseplants are sensitive to the excess moisture and nutrients that coffee grounds can introduce. These plants include snake plants, aloe vera and succulents or true cacti plants. With these houseplants, coffee is not the answer.
For these, use a succulent liquid fertilizer for best results. Affiliate Product Link: Succulent Plant Food for Succulents, Cactus, Jade and Aloe, Liquid Houseplant Fertilizer.
What About Flavored Coffee? How To Use Coffee Grounds & Coffee To Fertilize Houseplants
It is important to note that not all coffee is suitable for fertilizing houseplants. While plain coffee grounds are generally safe to use, flavored or artificially enhanced coffees can contain chemicals and additives that may be harmful to plants.
Similarly, decaffeinated coffee can pose risks due to the chemicals sometimes used in the de-decaffeinating process. Unless the packaging specifies that the coffee is naturally decaffeinated, it’s best to avoid using it on your plants.
Stick with plain coffee and simple blends made from different bean varieties. These are safe and provide the same benefits without any potential risks from artificial additives. By choosing the right type of coffee, you can ensure that your houseplants receive only the nutrients they need.
Reusing Spent Coffee Grounds
Even after brewing coffee tea, the used grounds still have value. While some of their nutrients have been extracted, they retain enough to be a valuable addition to your compost pile. Adding spent coffee grounds to your compost can enrich the organic matter, making it a great resource for your outdoor garden.
So what if you don’t happen to be a coffee drinker? Well, you can always use banana peels to power your plants too! For more on that, see our article: How To Use Banana Peels To Fertilize Your Houseplants – For Free!
Simple Garden Life
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Simple Garden Life is a website dedicated to keeping gardening fun, simple and enjoyable! We publish two new articles each week along with a new garden podcast episode every two weeks. This article may contain affiliate links.