Night Owl Coffee Roasters

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Ground Rules for the Garden

Okay, you've had your coffee and it's time to clean up. What do you do with all the stuff left over from the brewing process? Coffee grounds, paper filters, that last ½ inch of cold coffee you forgot to drink... Happily, all of these things can be composted or put to use in your garden.

Coffee grounds: According to a report by Soil and Plant Laboratory of Bellevue, Washington, coffee grounds contain significant amounts of phosphorus, magnesium, potassium and copper. They will also release nitrogen into the soil as they decompose, acting as a slow-release fertilizer. The pH is slightly acidic, which can be a boon to some of the more alkaline soils. You can mix coffee grounds into mulch, or simply add them to your compost pile or worm bin and watch them vanish.

Paper filters: Compost very quickly. No need to empty the grounds out of filters before you compost, except they're not very attractive just sitting on a compost pile. I've been dumping the grounds out of mine and then shredding the filters, which seems to work pretty well. If I had an enclosed bin or a worm colony, I'd just leave them intact.

Cold coffee dregs: Pour around your slug-prone flowers and plants. Slugs are repelled by caffeine, and can be killed by it at the proper dosage. Coffee-ground mulch around plants can offer the same protection.

Coffee roasting byproducts: Chaff, the papery brown bits you might find when you grind up a lighter roast, is a thin covering on the surface of the coffee bean. It's usually blown off during the roasting process, and becomes a waste product. Chaff works nicely in a mulch, and provides many of the same benefits of coffee grounds. One thing to watch out for: in high concentrations, wet chaff can glue itself together and block water absorption in the soil. Just make sure it's mixed well with your mulch and it will be a great addition to the garden. Chaff has also been used to good effect as a chicken coop liner.

Stale beans: Dark and shiny, stale beans can look great on paths or as an accent in your garden. Their lower surface area won't impart minerals and nutrients to the soil at the same rate as grounds, but will still provide a benefit. They may also help as a slug repellent.

Some of these byproducts may be available free from your local roaster or coffee shop, and are a nice way to cut down the waste stream and help out your plants. Do you have other uses for coffee waste? Let us know in the comments or on our Facebook page.

Remember to ask any coffee-related questions you may have in the comments or via email to media(at) and we will answer them in the next blog!


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