Can Coffee Grounds Be Used As Fertilizer?

Last updated on October 23rd, 2023 at 08:59 pm

You are a fragrant lover or just someone who needs a morning cup of coffee as a wake-up for an awake start to the day?

In any case, coffee brewing produces a lot of coffee grounds and you are now wondering if coffee grounds can be used as fertilizer?

Coffee grounds can be used as fertilizer for various acid-loving plants. More specifically, coffee grounds can be used both as a solid fertilizer, i.e. incorporated directly into the soil, or dissolved in water as a liquid fertilizer. On average, you can fertilize your plants with coffee grounds 4 times a year without causing over-fertilization.

Can you use coffee grounds as fertilizer?

In general, coffee grounds are very suitable as fertilizer for various plants.

However, we will look at why this is not true for all plants, fruits or vegetables in the next chapter.

First, the question arises why coffee grounds are such a good fertilizer.

This is mainly due to two factors:

Fertilizing with coffee grounds: these ingredients are beneficial.

Coffee grounds essentially contain 5 important ingredients: nitrogen, phosphorus, potassium, tannic acid and other antioxidants.

Especially nitrogen, phosphorus and potassium stimulate plant growth and strengthen cell structures.

Ingredients and effect of coffee grounds as fertilizer

If you compare the ingredients of coffee grounds with those of conventional fertilizers, such as those from Compo or Dehner, it becomes clear why coffee grounds can be so valuable.

Nitrogen, potassium and phosphorus are contained in about the same proportions in commercial fertilizers as in coffee grounds.

That’s why you should never throw coffee grounds in the residual waste, as they are much too good for that.

Coffee grounds as fertilizer improves the soil structure

Besides the great ingredients of coffee grounds, its structure is also very valuable.

Coffee grounds are inherently small and very finely ground. This loose, crumbly structure provides an ideal habitat for earthworms or other microorganisms that loosen the soil.

In addition, the granular structure of coffee grounds promotes air circulation in the soil by loosening it.

However, coffee grounds not only attract valuable soil animals, but also keep unwanted ones away.

Especially cats, snails or ants do not like the smell of coffee at all and thus stay away from the beds and flowers.

How to fertilize with coffee grounds?

Before you fertilize with coffee grounds, it is best to let them cool down. Otherwise, there is a risk that the moist coffee grounds will start to mold.

So it’s best to let the coffee grounds dry overnight in a shallow container (plate or shallow dish).

Now you can fertilize either directly or indirectly:

Direct fertilizing with coffee grounds

Direct fertilizing means that the coffee grounds are used directly on the plants.

On the one hand, you can simply take the dried, cold coffee grounds and work them flat into the soil of the respective plant.

In practical terms, this means, for example, that you take one to two handfuls of coffee grounds for your blueberry bush and work them flat into the soil below the blueberry (near the trunk).

This allows the nutrients to be absorbed directly by the roots over time.

This method is especially good for berry bushes or plants that are easily accessible.

On the other hand, you can also use lime coffee (so no coffee grounds!) for fertilizing.

This direct fertilizing method is especially helpful if you can’t reach the roots of the plants very well.

In this case you mix cold coffee and water in a 1:1 ratio and water the flowers or vegetables with it.

Here you should make sure that you do not pour over the leaves or the fruits but into the soil towards the root system.

Direct fertilization means that the coffee grounds are applied directly to the plants.

On the one hand, you can simply take the dried, cold coffee grounds and work them flat into the soil of the respective plant.

In practical terms, this means, for example, that you take one to two handfuls of coffee grounds for your blueberry bush and work them flat into the soil below the blueberry (near the trunk).

This allows the nutrients to be absorbed directly by the roots over time.

This method is especially good for berry bushes or plants that are easily accessible.

On the other hand, you can also use lime coffee (so no coffee grounds!) for fertilizing.

This direct fertilizing method is especially helpful if you can’t reach the roots of the plants very well.

In this case you mix cold coffee and water in a 1:1 ratio and water the flowers or vegetables with it.

Here you should make sure that you do not pour over the leaves or the fruits but into the soil towards the root system.

Indirect fertilizing with coffee grounds

Indirect fertilizing means not giving the coffee grounds or cold coffee directly to the plants.

That means there is an intermediate step, and that is through the compost.

So, over time, if you have too much coffee grounds to fertilize directly, just throw them in the compost.

Will that work? Well, sure! Learn more about the benefits of composting coffee here.

Can you use any type of coffee grounds for fertilizing?

Any type of coffee grounds can be used for fertilizing, meaning coffee grounds from all different types of coffee.

However, the acidity of the different types of coffee differs to some extent, and thus the effect on the soil pH when fertilizing is also different.

If you fertilize with a strongly acidic coffee grounds, the soil pH will decrease faster and further than if you use coffee grounds from a more mild coffee variety.

The acidity of coffee is a very complex issue and is influenced by different factors. In principle, however, it can be said that dark-roasted coffee (such as Lavazza* espresso) has less acidity, i.e. is milder.

Nevertheless, in practice, variations in the acidity of the coffee have such a small effect on the pH value that we can quietly neglect this factor.

So, as mentioned earlier, on the whole it doesn’t matter which coffee grounds you use for fertilizing.

How often should you fertilize with coffee grounds?

Depending on the plant, vegetable or fruit variety, you can fertilize with coffee grounds differently often.

It also matters whether you want to fertilize indoor or outdoor plants with coffee grounds.

For indoor plants it is sufficient to fertilize them 2 times a year, once in spring and once in autumn/winter.

With outdoor plants, it can get a little more complicated.

This is mainly because both the soil pH present in the garden and the pH required by the plant play a role. So depending on the combination, you can fertilize outside with coffee grounds at different rates.

If we look at all the different combinations of soil conditions and pH required by the plants (see table below), we see that on average you can fertilize your plants in the garden about 4 times a year directly with coffee grounds without any worries.