Composting Coffee Grounds

coffee grounds, compost, garden, Starbucks, free, soil, amendment

Photo: dyobmit

Jane commented a couple of times on my instant compost post, wondering about adding coffee grounds to her compost pile. (Jane, by the way, has a great movie review site – check it out!) She had heard that they are too acidic and can wreak havoc in a garden. I figure if Jane’s asking, other people may be wondering, too, so I did a little digging.

Science Daily says:

Contrary to popular belief, coffee grounds are not acidic. After brewing, the grounds are close to pH neutral, between 6.5 and 6.8.

According to the article, coffee grounds are a high nitrogen material and can be added to the compost pile in lieu of manure. In fact, one interviewee claims that he had better success adding coffee grounds to his compost than with manure. As long as you’re maintaining a fairly equal balance of carbon (straw, leaves) and nitrogen (coffee grounds, lawn clippings, kitchen waste) your compost pile will just keep on doing it’s thing. The Science Daily folks even say it’s okay to put coffee grounds directly around plants, so long as you top the grounds with a layer of leaves or straw. It’s kind of like composting in place.

Sunset Magazine commissioned a study of Starbucks coffee grounds and found that not only are coffee grounds a good nitrogen addition to compost, they can be directly worked into the soil for improved soil structure and:

Use of the coffee grounds at the specified incorporation rates (rototilled into a 6- to 8-inch depth) will substantially improve availabilities of phosphorus, potassium, magnesium and copper and will probably negate the need for chemical sources of these plant essential elements.

I’ve always added my coffee grounds to the compost pile or tossed them directly on my lawn. I am far (far!) from scientific in my methods, but I can tell you that I’ve never had a problem that I connected to coffee grounds. In fact, I think it’s a good day to swing by the local coffee shop and see if I can collect some of their waste!

 

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  • Susan W ,

    I just finished an article on soil preparation. My expert loves coffee grounds for nitrogen.

    • Kris Bordessa ,

      Susan, that’s good to hear! I love ‘em, too.

  • I used to hit up the coffee shop outside of Dave’s lab in Raleigh, NC (near NC State Univ.) for their leftover grounds. I had the most spectacular compost pile, and the most spectacular garden in NC — I’m sure due to the fantastic compost!

    One of the non-perks of a military life: moving every 2-3 years and saying goodbye to my compost pile and garden. I’m back in compost “infancy” stage here on the FL Panhandle, and it’s been a struggle with very little “brown” material to speak of. Very few leaves fall from trees here.

    But at least I know I’m not throwing those items in my landfill-bound garbage can, even if it takes forever before I can use it for my gardening.

    • Kris Bordessa ,

      I does take awhile to get a good pile cooking, doesn’t it?

  • Hey, I got my very own post here! Thanks for the great info, Kris. Will also pass the word along to my hubby, who does the bulk of the composting around here.

    • Kris Bordessa ,

      Let us know how it goes, Jane!

  • I’d never heard of any problems with coffee grounds in compost – good thing it was only a rumor, since I have a daily coffee habit and lots of grounds to get rid of!

  • Kris Bordessa ,

    Casey, me too. I find that my worms love the grounds as well.

  • Anjuli ,

    thanks for this information- I’ve been adding the coffee grinds to my flower bed and I must say I have seen great results. I get a full bag of grinds from our local Starbucks- they put out the grounds as a free giveaway for anyone who wants it- I seem to be one of the only people who grab it up each time.

    • Kris Bordessa ,

      I try to remember to ask Starbucks for their grinds. The last time I did, they were shocked – it seems nobody asks for them! A shame.

  • JoVE ,

    I’ve also heard they are good for deterring slugs. I think that’s in the “apply directly around plants” category.

    • Kris Bordessa ,

      Yes, I’ve heard that. And I just heard yesterday that they work for deterring/killing the coqui frogs that are a pest here.

  • My grandfather used coffee grounds to feed his worms when I was a child. They are very useful for that and composting.

    • Kris Bordessa ,

      My grandfather did, too. His worms were for fishing though – the composting was just what was required to make good bait!

  • Lynda Lee ,

    Kris, as a small girl growing up in the city of Denver, we had a huge yard with lots of grass. We had six kids and not a lot of money either – and one way we made a little spending money each was to “pick” nightcrawlers for the local bait shop! Our mom “fed” our lawn with the coffee grounds from her pots of coffee and both our grass and the size of the worms both prospered…and we continued to make our “penny per” for years and years! I have just planted my garden here in California and plan to use my grounds to nourish it!

  • Debra Kraus ,

    I have a friend that gets all of the coffee grounds from the local hospital’s cafeteria for her garden. They are free and her garden has thrived for years!

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