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The Glasgow Botanic Gardens Official Coffee Composting Recipe
So, you want to start composting.
Great! Did you know, used coffee grounds can be a fantastic addition to your garden? They act as an organic soil super food, adding extra nutrients to your soil. But to really get the most out of using coffee grounds in the garden, they need to be incorporated into a compost mixture with other organic materials.
Why?
Because compost requires a balance of “green” and “brown” feedstock to be able to properly break down. “Green” feedstock is wet and colourful (e.g. food scraps like used coffee grounds, grass cuttings) and “brown” feedstock is dry, dead material (e.g. twigs, fallen leaves, sawdust). Together they produce a perfect mix of nitrogen (green) and carbon (brown) to make nutritious plant food.
So, why don’t you give composting a go!
This guide will teach you how to make compost using the same recipe that the Glasgow Botanic Gardens does. The recipe is designed to produce large batches of compost and is ideal for those in community gardens or individual gardeners with larger gardens. Soon, your plants could be blooming as beautifully as the ones at the Botanics.
If you’d like to create a smaller batch, you can simply reduce the ratios or let Stevie, the Botanics composting expert, tell you more in our video down below. You can also find other used coffee grounds garden solutions in the toolkit here.
The Glasgow Botanic Gardens Official Coffee
Compost Recipe
Ingredients
- Coir (coconut fibre) – 300 L / 4 bags
- Bark – 30 L / ½ barrel
- Used coffee grounds (weathered for 6 months or more) - 30 L / ½ barrel
- Loam soil – 75 L / heaped barrel
- Osmocote fertiliser – 1.75 kg / 4 lb
- Ground limestone – 0.75 kg / 30 oz
- Magnesium limestone – 0.75 kg / 30 oz (if you can’t find magnesium limestone, you can add a little more ground limestone)
Steps
- To get the most nutrients from your used coffee grounds and benefit your soil, you must allow the grounds to weather for up to 6 months. Do this by storing them outside in a bunded area, such as a plastic compost bin, to ensure your pile properly weathers and you can control any potential runoff from contaminating the ground water. It’s ok to let the rain at it.
- Turn your used coffee grounds over with a tool like a shovel to aid the weathering process. This may also be done naturally with the help of worms! Don’t worry about having to buy any – they are attracted to the caffeine.
- Once your coffee grounds are prepared, you can mix all your ingredients together, like you’re making a big cake. Do this outside on a hard surface, such as a concrete slab, and use a shovel to mix your ingredients three times.
- Once everything is thoroughly mixed, put your compost into bags. Use some to spread over your soil or pot plants, and then store the rest in the bags.
- Make sure to use this mixture sparingly with ericaceous plants (i.e. rhododendrons, azaleas, camellias, hydrangeas) – coffee is quite alkaline, and these plants require acidic conditions.
NOTE: You can also use weathered coffee grounds as mulch on top of other, pre-mixed compost.