Myths and truths about the effect of leftover coffee grinds on plants

Myths and truths about the effect of leftover coffee grinds on plants

The idea that coffee grinds can be used as fertilizer in home gardens is increasingly widespread. And the good news is that in these organic materials so common in everyday life can bring benefits to your plants. Including increasing their production - provided that they are used appropriately and with caution. 

Coffee grinds have several applications in the plants we grow at home. If you compost, you can and should add the leftover grinds, because they are rich in carbon, help reduce the odor from the fermenting waste and also serve to aerate the compost. 

Even if you do not compost, you can still take advantage by using the coffee grinds in potted pants and flower/garden beds. If mixed with the soil, the leftover grinds help to maintain permeability, drainage of the soil and to support the microorganisms that are beneficial to the development of plants.

The use of coffee grinds is also positive in relation to microorganisms that develop from fermentation. Everything that ferments can generate positive waste for plants. Fermented coffee grinds are rich in nitrogen and help the soil's microorganisms to develop, serving as food.

For the purpose of fertilization, it is ideal to leave the leftover grinds fermenting for about 4-6 days before applying it to the pot. This way, the leftover grinds will have released more important nutrients. When applying, the grinds must be mixed with soil or other organic elements. 

You can also use coffee grinds to line pots - just distribute a little of the powder on the soil. It helps maintain moisture and protects the soil from the impact of overwatering or too much rain. 

The lining of pots and beds is very important so that other unwanted organisms do not develop. In this way, with the soil well lined, nature understands that it does not need to activate its genetic seed bank to make the land covered and protected. 

To make the lining with the leftover grinds it is very important not to compact the powder. It needs to be placed very loosely due to intrinsic oils of the grinds. If compacted, it can form an impermeable film. 

It is also necessary to be aware of the appearance of fungi. While some fungi are beneficial, the fungi that appear on top of the coffee residue can attack leaves, germinating seeds, the younger seedlings or compromise species that are already weakened due to other problems. 


Balance is key

Despite the benefits, it important to be remember that moderation is key and anything in excess can cause problems for the plants. Excessive use of grinds could cause intoxication of vegetables and soil because the plant will be receiving a high amount of some nutrients and low of others. 

The use of grinds does not work miracles, because for plants to develop in a healthy way, they must be grown in favorable environments and adapted to the needs of each species. There needs to be balance and proper conditions.

The plant needs water. This is the most important element of all. If we don't water properly, there is no point in saturating the soil with fertilizer and organic matter; the plant will not develop or will die due to lack of water. 

What about liquid coffee? Any coffee left in you cup can be used. The liquid is rich in caffeine, which is a biostimulant. Just as caffeine stimulates us, it stimulates vegetables. With caffeine, plants react by eating more and, consequently, produce more. However it is necessary that the soil is balanced, so that it seeks nutrients and finds them in the soil - otherwise, the plant will only be "more hungry." 


The biggest benefit

The biggest gain of all is the reuse and thereby reduction in waste. The benefit of reuse is that, in addition to this product being used as an additive for gardening and agriculture, providing an environmental gain, there is also an economic gain - since there is no cost of disposing the waste. 

The ideal is that we can recycle more and more of the waste we produce. 

Article translated from Gazeta do Povo. Read more at:


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