Coffee grounds are often recommended as a cheap and environmentally friendly fertiliser for geraniums or houseplants. But is this a good idea if you are primarily thinking about abundant flowering? The experts at my-geranium.com advise against it for four reasons. 

What remains after brewing coffee actually contains some important nutrients such as nitrogen or potassium and even small amounts of sulphur, which can benefit the plants.   

However, this is not enough. Geraniums need plenty of nutrition to grow lush and bloom profusely. Geraniums fertilised exclusively with coffee grounds are highly likely to suffer from nutritional deficiencies and fall short of their vigourous flowering potential. 

Another argument put forward by proponents of fertilising with coffee grounds is the quality of the compost. Coffee grounds can indeed improve the soil structure by promoting the growth of certain microorganisms. This is true.   

In the garden, this brings long-term benefits, but on a balcony, where the compost in balcony boxes is replaced every year, this effect is not relevant. In addition, earthworms and the like play virtually no role as guarantors of active soil life on a balcony. Our advice: Buy a good growing medium instead. You can garden sustainably with peat-free potting compost. 

There is no denying that coffee grounds lower the pH value of the soil. The pH value makes the various nutrients more or less available to the plants. Blue hydrangeas, rhododendrons and redcurrants have adapted to a low pH value, i.e. acidic soil.  

However, geraniums prefer neutral soil, which is why the pH-lowering effect of the coffee grounds is counterproductive in terms of lush flowering and healthy plants. 

A common misconception is that you can simply sprinkle coffee grounds on the compost to fertilise your geraniums. But this usually only leads to mould growth and sealed soil. Water then penetrates the soil less easily.   

To use coffee grounds effectively, they must first be dried, then worked into the soil as a powder. This is difficult when you realise how densely rooted a geranium balcony box is.   

Using coffee grounds in the garden is easier. Much larger quantities can be used in flower beds than in balcony boxes. But even there, a thin layer on top of the soil is counterproductive. If you absolutely want to fertilise with coffee grounds, you should work the dried powder into loosened soil. 

Good news! Geraniums are rarely visited by pests such as aphids or snails. It’s easier for them to eat other plants. That’s why there’s no need for caffeine or coffee grounds in a flowerbox on your balcony. 

So, are you wondering how you can fertilise your geraniums, then? There are much better options than using coffee grounds as a fertiliser.   

• – With liquid flower fertiliser specially developed for geraniums or flowering plants, you can easily provide your summer flowers with all the valuable nutrients they need to bloom.   
• – Slow-release fertilisers in various forms ensure a continuous supply of nutrients for your flowers without you having to constantly top up. If you tend to forget to fertilise, they are the solution for you. In our eyes, this is the perfect fertiliser. It’s best to use one that works for 8 to 9 months.   
• – Ask in a garden centre for biological or organic flowering plant fertilisers if it’s important to you to use a natural feed made from renewable ingredients.   
• Find out everything else you need to know about Fertilising geraniums in this article. 

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