Are coffee grounds good for your worm farm and compost?

Do you have leftover coffee grounds being tipped into the bin each day? What if we told you that they could go straight into your worm farm and compost bin! We were recently asked by a client if they could use their leftover coffee grounds in their worm farm, so we thought we’d share.

Coffee Grounds In Worm Farms

Coffee grounds are highly suitable for worm farms by providing a natural pesticide to ward off pests such as snails, slugs and ants. Since worms have no teeth, the fine particle size of the grounds helps make it easier to consume and provides a gritty substance in their guts which helps them grind and break down food.

Coffee grounds have about the same amount of nitrogen as grass clippings, therefore they heat up quickly when added into organic matter. Therefore, you should only add coffee grounds in moderation to help avoid killing your worms. The temperature can be reduced by adding carbon (shredded cardboard, newspaper, dried mulched straw or leaves) and improving the air ventilation.

Due to their slight acidity, coffee grounds should only be 25-50% of a worms diet. It’s a good idea to start adding small amounts in the beginning to see if your worms like them or not. It’s also important to make sure that the grounds are always moist, not dry before adding to the bin.

Coffee Grounds In Compost

Coffee grounds are too acidic on their own to be used straight on the garden, but once mixed with other organic matter such as manures, or organic garden waste, they make a great compost mix.

Simply add the coffee grounds into your compost bin, keeping in mind they are a green material and will need to be balanced with some additional brown compost material such as dry leaves, wood chips, sawdust or newspaper. As a rule of thumb, a good mix of brown and green materials should consist of a ratio of 4:1 browns (carbon) to greens (nitrogen).

The nitrogen in coffee grounds is crucial for providing energy to the bacteria in soil. This bacteria transforms organic matter into compost that plants can then use for nutrition.

In addition to the coffee grounds, paper coffee filters can be added to the compost bin as a source of carbon. Simply tear them into small pieces to speed up the decomposition process.