Ella Takalainen //
// 29.4.2019

How To Make Your Garden Flourish With The Power Of Coffee

We have had some experiments regarding used coffee grounds. There was a project in Baltics where it was converted into electricity and of course there are all the face masks and scrubs lots of ladies out there have tried out.  But electricity isn’t something I can personally make at home and with my coffee consumption I wouldn’t have no face left if I would use it all for scrubs :D It got me thinking about what else could I do with my coffee leftovers and decided to dig little deeper into the compound itself and to find out if I could use it in some gardening project.

Because it seems there was quite a little research about the subject I had to ask counseling from a gardening pro and that’s where Esamatti Laakso from Plantanet stepped in for helping me. We made a plan to start our coffee related experiments with a simple mock up. As my plan was to make a mini garden to grow some veggies and herbs outdoors we also had to consider coffee grounds could be something that pests and animals would like to eat as well, so that had to be tested as well. I really would not like generate a huge pest problem by accident!!

coffee solves problems

Practically I had two options to choose from: I could use the coffee as cover for my plants or to mix it into the soil I would be using for my plants. The cover is mostly visual thing (also might help the plants to preserve moisture better) but it had to be tested. After a week my coffee cover started to look quite unpleasant and moldy. So I decided coffee wouldn’t work as a cover for my plants. This was a bummer because I was hoping to add some coffee on top the soil and coffee mixture as a cover to protect my plants but also as a visual coffee like feeling. 

Esamatti told me to check the NPK-values in the plants and then start experimenting with different amounts of coffee grounds of mixed into the soil. NPK- values are something that is stated in the soil bags and it refers to the nitrogen (N), phosphorus (P), potassium (K). There are substances that are present in the soil already. The NPK- value is something that has to be matched with the plant used in the soil. Meaning there are different soils and certain plant flourish in different soils. I decided to use barley seeds as they would grow fast so I wouldn’t have to wait for the results for long and the NPK match was good. The NPK values for coffee seemed to be very low so I needed a soil with high NPK figures.

PH values should be about 7 in the mixture of coffee and soil used in the tests. The Soil I used was 6,5 pH, so just a bit acid to start with. Because coffee brings lots of acidity to my soil I needed to look for plants that would love the acid soil. After little Googling it turns out there is lots of these little acidity lovers. For example potatoes, bell peppers, parsley, blueberries, carrots and many others.  


But before being able to start actual growing I had to first try what kind of coffee to soil ratio would be good for growing. I did very simple test where I mixed different amounts of coffee to regular sowing soil. I used more or less 70 % coffee for first mixture, 30 % for the second and just the soil for comparison. I watered the mixtures and covered them with a plastic film with few holes on top. Surprisingly the seeds germinated really fast and first it seemed like they didn’t like the coffee mixtures at all. But luckily after few days the situation evened out and after a week the score was almost identical for both the 30 % soil mixture and the pure soil with no coffee in it. 


I also tried if coffee would interest some pests by laid used grounds outdoor and waited. But it seemed like ants, bugs or anybody didn’t really care. It’s not super scientifical but it was enough for me to believe that my coffee experiments wouldn’t bring a huge pest problem to my plantation.  Because that would really suck all the joy out of gardening.

After about a week my home experiment was done and as anyone can see from the picture under it seems the grass I was using did quite well in the 30 % mixture but the 70 % was too much for the little guys. So the conclusion is that I definitely want to try gardening in bigger scale with more plant variants, especially the acidity loving plants mentioned above. 


I can most definitely recommend adding some coffee grounds into your garden especially when growing vegetables. And personally I'm sure to try this out in bigger scale asap. Maybe even a coffee tree in the coffee soil, it sure would be nice cycle of life.