It is 8 am in the morning, you make yourself a fresh cup of coffee, and while sitting by your table you start to think: What can I do with my coffee waste? Can I use it as a fertiliser? I mean, it looks like dirt." You are not alone in this, a lot of people are writing about fertilising with coffee and there are also a lot of articles online that say you shouldn't fertilise with coffee.
So, what should you actually do? Can you use coffee waste as a fertiliser or not? We will cover this now to end it once and for all and even if you live in a metropolitan city, this information is still useful to you.
What makes coffee a good fertiliser
We can all agree that coffee is good for us, it has caffeine, minerals, vitamins and makes our lives more enjoyable. Can we say the same about coffee for the soil? It has minerals, vitamins, also nitrogen, potassium and phosphorus. It can add to the fertility of a soil in a garden, making the flowers grow more and giving precious food to the organisms living in it.
Potassium helps plants circle and move water, nutrients and carbohydrates inthe plant tissue. Phosphorus is connected with plant growth and photosynthesis. Basically, spent coffee grounds are a great ingredient to add to your garden. So why do some say you should not use it?
Why you shouldn't use coffee as fertiliser - the argument
It turns out, that even though coffee has all these great benefits, it is still not good to use as a fertiliser. As Rural Sprout points out, coffee grounds compact too quickly which means that they don't breathe to let water and air in as well as out of the soil. Strike one!
Secondly, it is also not good for earthworms. A study conducted on differences in three composting methods using coffee grounds revealed that in all three instances, there was an increase in the death-rate of earthworms. Strike two!
And thirdly, this is a big one, caffeine is not good for plants. From an evolutionary perspective, caffeine was born as mutation in plants which was copied and given on through evolution. Caffeine gave plants an edge over other plants as the fallen leaves of the plants supposedly poison the soil and repel other plants from growing on that area. These types of plants include cocoa plans, tea plants and coffee trees. Talk about being ruthless....Strike three and they are out!
Conclusion - what now?
What are the key takeaways from all we have read? Firstly, it is still good for humans to consume coffee in a reasonable dose. Secondly, it probably is not a good idea to use coffee grounds as a fertiliser, mainly due to its caffeine rich property. Thirdly, you can use coffee to kill off or inhibit the growth of plants you do not want in your garden.
And finally, though you may not be able to use coffee as a fertiliser, you can still use it in other applications, and we did a whole blog about it which you can check out here! Pro tip: point number 2 is the best by far as you can do it anywhere.