Waste not, want not! Coffee grounds as a garden fertiliser

Waste not, want not! Coffee grounds as a garden fertiliser

We produce our coffee extract from real coffee beans and filtered water – nothing else. Using 100% Arabica beans gives you the most authentic and best tasting coffee going around – but it does leave us with leftover coffee grounds. We hate waste, so we started exploring different ways in which we could make use of our spent coffee grounds.

Here are some facts!

  1. The use of coffee grounds in garden soil will improve the soil’s structure straight away! It will also continue to improve the soil over time. Coffee grounds can make up 35% of the total soil volume but any more than this and you may start to lose the benefits.
  2. When coffee grounds are added to soil, the availability of phosphorus, potassium, magnesium and copper are substantially improved. These elements are vital to soil and plant health.
  3. Nearly all potassium and all magnesium from the coffee grounds are in the available form. This means that immediate availability improvements for these two elements will take place when the coffee grounds are blended with mineral soils. About half of the copper and calcium are in their immediately available forms.
  4. The addition of coffee grounds to soil eliminates the need to add supplements of the elements above (which are often costly!).
  5. Over the long term the coffee grounds will act like a slow-release fertiliser providing long-term nitrogen input which can then be utilised by plants.
  6. The acidity of the coffee grounds as well as the ions in sodium and chloride were found to be low enough that they did not have any negative impact on plants.

NPK Values

Nitrogen, phosphorus and potassium are the main ingredients in most fertilisers and are the macro-nutrients used by plants.

  • Nitrogen (N) – is largely responsible for the growth of leaves on the plant.
  • Phosphorus (P) – is largely responsible for root growth and flower and fruit development.
  • Potassium (K) – helps the overall functions of the plant perform correctly.

All three of these elements are found in spent coffee grounds in good quantities:

N: 2.28%

P: 0.06%

K: 0.6%

The next time you make your morning brew, instead of throwing your coffee grounds in the bin or flushing them down the sink, add them to your compost bin, or mix them into your garden soil. Make sure you’re not adding too much though, as you don’t want the acidity of the grounds to harm your plants.



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