Vermicomposting coffee grounds
Coffee grounds are an excellent and very popular addition to your Bonter vermicomposter. Worms love them, they provide valuable nutrients, and they improve the structure of the compost bin. An ideal and easy way to process this common kitchen waste and contribute to your compost.
Can coffee grounds go in your worm bin?
Yes, absolutely! Used coffee grounds are very suitable for vermicomposting. They are a good source of nitrogen (‘green’ material) and contain minerals that are useful for the compost. In addition, coffee grounds have a fine, granular structure that helps with the aeration of the compost and serve as ‘grit’ for the worms, which supports their digestion. Contrary to popular belief, used coffee grounds are relatively pH-neutral and therefore not too acidic for the worms or the composting process.
How much coffee grounds can you add?
Coffee grounds can be added regularly to your Bonter, in reasonable quantities. Like all ‘green’ (nitrogen-rich) material, it is important to maintain a good balance with sufficient ‘brown’ material (carbon-rich, such as shredded cardboard, paper, dried leaves). Do not add a thick, compact layer of coffee grounds all at once, as this can clump together, reduce aeration, and lead to anaerobic conditions. Mix it well with the waste and existing bedding in the bin. A few scoops at a time, well distributed, is fine.
What to do instead? Alternatives & waste management
Coffee grounds are so suitable and useful for the Bonter that you can almost always put them in there! Worms are happy and efficient at processing them. If for some reason you have an exceptionally large amount of coffee grounds, they can also go on a traditional compost heap. They are also a good soil improver directly in the garden (in moderation) or can be used as a scrub. Above all, ensure that coffee grounds do not end up with residual waste; it is a valuable resource for compost.
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Tips for composting coffee grounds
Always mix used coffee grounds well with the other waste and existing bedding in your Bonter. This prevents them from clumping together and hindering aeration. Add sufficient dry ‘brown’ material (such as shredded coffee filters, cardboard, or paper) to balance the moisture content and the carbon-nitrogen ratio. Bury the coffee grounds under a layer of bedding. The Bonter’s air filter helps with odours, but a well-aerated bin with the right mix of materials smells fresh and healthy.
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Frequently asked questions about vermicomposting coffee grounds
Are coffee grounds too acidic for worms?
No, used coffee grounds are relatively pH-neutral and not too acidic for compost worms. They are safe to add.
Do coffee grounds attract pests?
Do coffee grounds serve as food for worms?
Should I mix coffee grounds with other waste?
Do coffee grounds provide grit for the worms?
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