5 Ways To Use Coffee Grounds In The Garden

At a certain point I might as well admit that we drink a rather obscene amount of coffee. It’s almost all frugal, brew-at-home type coffee, but still: that stuff ads up.

Luckily, the grounds are almost as valuable as the liquid coffee, and we save them for use in the garden, thereby getting the most bang for our fair-trade-coffee-buck.

5 Ways To Use Coffee Grounds In The Garden

These are my five favorite ways to use coffee grounds in the garden.

Sheet Mulch

The majority of our grounds get dumped out, directly on the soil, as sheet mulch around around our berries and fruit trees. The common assumption is that coffee grounds are acidic, but tests on the pH of grounds have shown results from mildly acid to mildly alkaline, and research indicates that the pH of the grounds tends towards neutral as it decomposes. I use coffee grounds as a mulch around blueberries, fruit trees, currants and cane fruit, all with good result.

When you mulch with coffee grounds, don’t pile it on. That’s a sure-fire way to get moldy mulch. A good half-inch thick layer atop your normal organic mulch in any one spot will do nicely. It will break down relatively quickly as worms and soil microbes go to work, and when it does you can add more. Coffee works like any other organic mulch, with a few added advantages discussed below.

Side-dressing for Heavy Feeders

You probably know that the main nitrogen component in DIY organic fertilizers, like Steve Solomon’s famous mix, is seedmeal. Well, if you think about it, a coffee bean is a processed seed. As you’d expect, coffee grounds are high in nitrogen, at about 10%. Depending on the exact beans and extraction process, “the carbon to nitrogen ratio of coffee grounds can be as low as 11:1, an ideal ratio for plant and soil nutrition,” according to WSU extension.

With nitrogen levels like that, pure coffee grounds make an excellent side-dressing for leafy greens and hungry fruiting veg, like tomatoes and squash, early in their growth. I particularly like side dressing spinach with used coffee grounds.

Natural Slug Deterrent

Slugs get the heebie-jeebies crawling over coffee grounds. I think it scratches their slimy underbellies in an unpleasant way. Do you have some veg, like Napa Cabbage, that seems like a total slug magnet? Try banding coffee grounds in a uniform circle around the plant as a seedling, and keep the band topped up. It helps. I’m not giving away my Sluggo just yet, but it helps.

Vermicomposting

I know some people say that you shouldn’t feed worms coffee grounds, but I have Seattle worms. They’re all holding teeny Starbucks cups and wearing fleece vests as they crawl around their worm bin, talking about Python hacks and when they’ll finally be able to get up to the mountains to go snowboarding.

Coffee grounds aren’t the only thing I put in my worm bin, of course, but mixed in as part of a balanced diet of cardboard, shredded paper, kitchen scraps, banana peels and the like, the worms seem to process coffee grounds without any issue.

Suppression of Fungal Diseases

Decomposing coffee grounds have their own fungal and mold colonies and those fungal colonies tend to fight off other fungal colonies. If this seems weird, just remember that the antibiotic penicillin was developed from a mold. The world of teeny, tiny things is fighting for space and resources just as fiercely as the world of big, visible things, and you can use that to your advantage.

The natural mold and fungus colonies on coffee “appear to suppress some common fungal rots and wilts, including Fusarium, Pythium, and Sclerotinia species,” according to research. It’s hard to quantify exactly how this all plays out in the big outside world with millions of variables, but incorporating coffee grounds into your compost may help to prevent build-up of nasty verticulum and fusarium wilt inoculates. I figure it’s worth a shot. If I have coffee grounds on hand, I will throw a handful of grounds into the transplant hole for tomatoes, peppers or eggplant, since these plants tend to be susceptable to various wilts.

How do you use coffee grounds in your garden?

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Comments

  1. “How do you use coffee grounds in your garden?”

    Pretty unsophisticated, but everyday we have a big bucket that we use for scraps. Grounds go directly in there along with everything else. We cook at home almost 100% of our meals, so I estimate we generate a solid pound of compostable “waste” per day.

    Depending on the overall content, I rotate this stuff into a variety of piles, and the special stuff goes to the chickens. My wife is Venezuelan. She has trained the chickens to come running at her sight or sound. On Sundays, I usually wake up to a loud “Muchachas!!” and they all come running as fast as you’ve ever seen a chicken run.

    I keep the grounds away from the chickens. Don’t know why — just doesn’t seem like a good idea.

    Anyway, good post. I’ve been thinking about harvesting the grounds in my office. There’s plenty of good compostable material getting thrown away.

    Thanks!
    pat

    • Hi Pat, thanks for stopping by! :)

      • phyllis waczkowski says:

        I put coffee grounds on my roses they love it !!! Thanks for the tip on other things !!

      • Just wondering if coffee grounds are good for house plants and grass? If it’s good for the grass I hope it’s not as good for the weeds! Also are the critters attracted to it..ants, earwigs, spiders…..?

    • My chickens do the same thing! I just have to be by the window or door and suddenly all the girls are headed my way, full speed ahead. Love it!

      We keep a compost bucket by the backyard to dump the smaller counter compost container in. When it starts getting full, out I go to add it to the pile. I tend to keep the coffee/grounds separate so I can add them direct to a garden bed, but most of them end up in the compost pile.

  2. Ha! I scater the stuff around but we consume a LOT of coffee. I am pretty certain that my compost is as much as 20% coffee grounds AND the fliters (the unbleached kind).

  3. I have a worm bin and feed a LOT of coffee ground to my worms. The instructions that came with the bin said it’s like ice cream to them… a treat. They devour them. (I have red wigglers)
    I also found a lot of worms in my wine barrel planters.. so I saved some coffee grounds for those worms too.
    I just harvested 1/2 of a 5 gal. bucket of castings.. I like keeping my worms fired up with plenty of coffee grounds.
    I haven’t found it to be great for slugs.. but I keep trying!
    Good post. :)

  4. I’m so excited to use the coffee grounds on my fruit trees. Can they be used on every fruit tree? I use them on my blueberry bushes, my honeysuckle vine (it’s leafing out in a very dark green this year), my garlic and rhodies. I use them on my houseplants..my aloe plant and my money tree plant. I actually planted some hollyhock seeds I accidentally dropped in the sink directly into the coffee ground mulch in the money tree plant, and they are growing happily. :) Coffee is wonderful, and

  5. Huh. I never thought of coffee grounds as a seed meal, but you’re right. They are, aren’t they? Our coffee grounds — we don’t generate that many — go into the compost bin with everything else, but now I’m thinking they might be more useful as a side-dressing fertilizer during the growing season.

    Since you mentioned him, I just finished Solomon’s book The Intelligent Gardner. It was… interesting. Gardening does seem to generate Personalities, doesn’t it?

  6. Janet in Seattle says:

    Thank you for the encouraging posts about feeding coffee grounds to composter worms! We have red wigglers, too. (I call ours the Paris Commune.) I’ve been wondering about ways to best use the coffee chaff and old roasted beans when I roast coffee at home, but have been reluctant to feed these to the worms because I fell for the vermicultural propaganda. Not any more! We also have a very divaesque gardenia that’s temporarily indoors for the winter; I may give her and the lavender shrubs some grounds, too.

  7. I just throw coffee grounds in the compost bin. With its nitrogen content it’s a good “green” (even though it’s brown) for helping to break down my “browns”.

    One caution – keep an eye out for dogs after you’ve spread the grounds. I don’t know if coffee grounds would be all that appealing to a dog, but many will eat anything that’s not nailed down and with the high caffeine content in coffee, a dog could get into serious trouble. Dogs can’t process caffeine well at all – many have died from eating a relatively small amount of dark chocolate (semi-sweet chocolate chips, baker’s chocolate, etc.) which contains a similar chemical compound. Cocoa shell mulch can also cause problems. It makes sense that there’d be a similar risk from coffee grounds as well.

    • Hey, Kathy have you heard about chickens eating grounds?

      • Do not fed the grounds to the chickens! They will over eat them readily. The oxalic acid in coffee grounds is extremely high. It will bind with the minerals and prevent the Chickens from absorbing them. Resulting in soft shell eggs which will eventually become life threatening to the chickens as their bodies become depleted .

  8. Thanks for these great tips. I am new to gardening & havent used my coffee grounds yet. On a side note, I suspect my Australian worms are nowhere near as cool as Seattle worms ;-)

  9. Thanks for the info! Here, in the snowless months they go on the blueberry beds. In the winter they go straight to the compost.

  10. Thanks for the idea! I will definitely start saving my coffee grounds for my minuscule Michigan garden. Can they be saved (without getting moldy) for the Spring/Summer when I’ll need them, or should I just toss them out on the soil all Winter?

  11. We drink enough coffee every day here to generate a tidy mound of grounds, but it just goes into the sheet compost layers for now. I’ve found a few nightcrawlers along with lots of red wigglers in the clumps of grounds and cardboard. Hopefully, there won’t be a new round of anti-coffee research articles, as we see the next flurry of scare pieces about alcohol now. I’d really like to compost the junk-science and political-correctness articles!

    • Homebrew Husband says:

      Fortunately I thik we’re in the middle of a wave of just the opposite sentiment – the health benefits of coffee (especially for women) seem to be getting the popular-press science reporting focus these days!

  12. I sprinkle used grounds and sometimes fresh ones (from old beans) all around my yard and garden and even on my deck. It is supposed to be a cat deterrent, and seems to be working. The benefits to the grass and soil is a bonus.

    I read a posting some where that it could be toxic to dogs if they were interested in them. My dog isn’t. Maybe because he gets a real treat when he howls as I grind the beans to make the brew!

  13. Omg, are you serious? Coffee grounds will (help) keep a cat at bay?? I am total cat person but my neighbors cat has a big ol bullseye on its back! It’s will def help remove the target. I’m a gardener before cat person & this cat keeps getting into my pots. Thanx for the 411!!

    • I have 2 loveable, non-rehomeable special needs kitties. I love that they prefer to use the great outdoors as their litter box, until this spring when I found kitty rocca in my raised beds where I wintered over my beets and carrots. Utterly disgusted! Good luck with Bullseye!

  14. Excellent post. Thank you.
    I learned a bit of new info here.
    We save all of our coffee grounds and collect from a couple of our favourite cafes. We have a large compost pile that much of our coffee goes to. We spread it very thin (unnoticeable) on the lawn and through our bushes and flower beds. Great to know it can be a slug deterrent as well.

    FYI: There are many coffee shops that are not saving coffee grounds for composting. Much of this magical material is hitting the land fill. I suggest to everyone to inquire with your local coffee place spot and see what they are doing. Even if you have no use for the coffee, share the info with a local gardening group to set something up.

    • I scored almost 50 pounds of coffee grounds from a few of the chain coffee shops all within 2 miles from my house. 50 pounds of “roasted gold” in one night, I am dancing around like I lost my mind! The weirdest things make a gardener happy, like spotting a garbage bag of leaves setting on a curb, or a big box from someone’s new fridge… Happy Spring to you!

  15. The funny thing about this post is that I clicked on it from another site, and poof there you are! Love it when you stuff get’s “re shared”. Anyway, I will be using more of our coffee grounds this year for sure! I read somewhere, that coffee is good to spray on slugs. I somewhere is a big place, so I will see if I can find it!

  16. Wence Dusek says:

    I knew there was a reason I wanted to separate the grounds from the rest of our compost. Now I know.

    I also remember my granny using these around her indoor plants as a mold and insect deterrent. She also soaked tobacco in water and sprayed it on her plants to keep aphids away. She would buy cigars just to take them apart and soak them. One went a long way. Anyone knows about this?

    • Yes, that’s a traditional organic insecticide recipe that is coming back in popularity. Nicotine is wicked toxic. http://www.sciencedaily.com/releases/2010/10/101027124734.htm

      • Wence Dusek says:

        Thanks Erica. That’s a great link. I just wonder if you my vegetables would contain nicotine with that.

      • Are there any risks with this? Isn’t there a tobacco mosaic virus that can spread to some other crops just from growing tobacco plants too close to them? or does the processing of the leaves kill that off?

        • it only affects tomatoes. DO NOT use a tobacco based spray on tomatoes!!! or even handle your tomato plants after smoking, without washing first. anything else, you can use tobacco-based sprays on – most flowers, except roses, love it!

    • I love the idea of buying the cigars to get the tobacco for an insecticide. Wonder if that’s cheaper than chewing tobacco…

      • Wence Dusek says:

        No idea but These days I would look for the most organic version. A tobacco product with the least additives. Will have to look into it. Living in North Carolina though, I can probably just take a drive in the country some day a pick a fresh leaf or two right of the field somewhere.

      • Oh! Don’t use chewing tobacco… I think it has other stuff in it. Cigars are nothing but tobacco leaf pretty much, so would be much safer than many other forms of tobacco.

    • Maybe the bagged, aka” roll your own” tobacco? I don’t know if they add as much weird stuff as the “mainstream” cigs… I noticed that cigars often smell like mildew to me…

  17. Love the picture of the Seattle worms. Great tip about adding grounds to tomato holes. I did have mold in the greenhouse and was not able to remove the dead plants last year. Any evil micto organism that preys on tomatoes has been able to overwinter.

  18. Simple and super garden tip.. Thanks for sharing this post..

  19. You’ve inspired me! Normally, the grounds go straight into the compost pail. As I’m preparing our beds for spring planting, though, I’m thinking I need to mix some of these grounds right in!

  20. I have found that coffee grounds also produce worms. I also mix felt from dryer in with coffee grinds. It breaks down the felt when mixed with the grinds . I tend to put seeds in with them and wala a new plant:O)

    • karen halvorsen says:

      dryer lint is radioactive as is all dust which collects on electronics-don’t let your cat or other pets lay on it as they will ingest it when they groom themselves.

  21. I’ve always composted my coffee grounds, and also put them directly on the beds near the kitchen in the winter time. Another unusual way I used them is I dried them out then used them as a small indoor sand box for my toddler. The dark brown grounds inside a plastic box made a unique play area for mini trucks and cars. A good winter activity for a change.

  22. Your articles are so thoughtful! Has anyone seen this? http://extension.oregonstate.edu/lane/sites/default/files/CoffeeGrdTrial.pdf uncomposted coffee grounds didn’t do much for the bean plants in this study. Sunset did a report on them too… http://www.sunset.com/garden/earth-friendly/starbucks-coffee-compost-test-00400000016986/ and indicate that the nitrogen in used coffee grounds is unavailable to plants until it is broken down by microbial activity. I’ve found that scattering grounds on grasses improves tilth and doesn’t seem to turn the grass blades yellow or otherwise burn them if you don’t lay it on thick. If you fumble the container, a rake works well to spread out the mound. Two inches or thicker will develop a stink if the environment is moist; be considerate of any nearby neighbors. Avoid problems by mixing well in your compost pile, not leaving clumps, and going thin on uncomposted grounds used as dressing.

  23. Stirred oyster mushroom spawn into coffee grounds, put in a plastic bucket with holes drilled into the sides and bottom….and in short order, the mushrooms DID start popping out.

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  26. Janet Bowen says:

    I am brand new to this website, thanks to my friend who loved your blog called The Terrible Tragedy of the Healthy Eater. That was fabulous-had me in stitches! I am also semi new to gardening here in Alaska-we just built a nice hoop house in the back yard. So by side dressing with coffee grounds, you mean basically sprinkling the grounds directly around each young plant? Are there any plants you would not want to do this to?

  27. lola josey says:

    Moat coffee houses stack large bags of grounds by the doors for gardeners to pick up…there are many other uses as well. The waste associated with K cups makes me crazy….I am pulling the top off, scooping the grounds out (and into the soil!) adding potting soil to the cup (leave filter in). They are perfect size to test seeds…lined up on a windowsill tray or any tray from grocer that is plastic and narrow…drainage hole is already there but you could add another or two

  28. lola josey says:

    Presently am working with billions of seedlings..if you cover them with nylon tulle it keeps bugs off and there is no necessity to use chemicals….once you start using chemicals, conditions are set to have to use more and more so it’s easier to never start.
    My favorite short term plant marker is a 5″ cut length of venetian blind…lean towards tiles for more permanent but lacking a forrestry pen, use acrylic paint for plant names…holds up for years with no fading.

  29. Hi Erica! We met at the MMM meeting in Seattle this Spring. I just googled “coffee ground uses” for my garden here in my new home in Australia, and was very happy to find your blog as #1 in the list. When we met, I told you I really wanted to garden more, but that I travel every June, July and August (which you whole heartedly supported over staying home!). Since then, I’ve decided to take a year off and am now living abroad AND gardening :) Best of both worlds, at last. I’m really looking forward to following your blog (and working on my own brand new one) and getting some good gardening tips while maintaining my Mustachianism. Thank you!

  30. Carolyn Cavender says:

    I’ve also had lots of success putting coffee grounds around Rose bushes about twice monthly too. They seem to help the buds open up better and prettier too. Also I noticed that new shoots appear afterward too.

  31. Chrisitna Rozema says:

    I use them as a top dressing on a Meyer lemon and a lime tree that I have. They seem to like it but I am really excited reading about all the other uses….now I have a reason to save all the grounds we produce! Thanks….

  32. shylarose says:

    Has anyone tried coffee grounds to keep rabbits out of the garden? The only thing I have left is tomatoes. Rabbits haven’t bothered them!

  33. Russ Denton says:

    Two cups of coffee a day gives me a half litre of grounds a fortnight; a banana every day, I chop the skin and fill a bowl a fortnight. Then I mix them together: coffee for nitrogen, bananas for potassium! I put it neat around specific plants, roses, hibiscus,lilies etc, or add some potting compost and spread the mix around for a general fertilizer . And the veg love it too! And the worms!

  34. I wrote about coffee grounds a couple of years ago on my site. I was worried that they were too acidic since I read both discussion (yea and nay.) I ended up interviewing one of the scientists at Rodale Institute for the article. He concluded exactly what you said.

    I also use the coffee on my roses as well but not too much.

    I didn’t want to link the article in your comments since I didn’t know your comment policy. The Rodale scientist was fascinating and gave me some good pointers about using coffee grounds. Let me if it is okay. You are welcome to go to my site and link up your article with mine in the comments.

  35. Roxanne Churchill says:

    Very interesting

  36. Veronica Hunt says:

    Banana skins are wonderful for roses.jut lay them at the bottom of your rose bush.

  37. Love this site!!!

  38. I literally belly laughed when I read the “Vermicomposting” paragraph. The visual was brilliant! HAHAHAHA!

  39. You had me at “Seattle worms.” Go Hawks!

  40. We only use about 5 to 10 Tablespoons of fresh grounds per day so I place the used grounds into an old coffee can and then when it is full I place them around all of our plants and trees. Sometimes I will work them into the soil and other times I just spread them around on the top. I like to work them into the soil in the flower garden areas. I’m 72 and I learned this trick from my Mother when I was growing up.

  41. My experience is that some retail stores such as Starbucks and Caribou are happy to give away their grounds. Non-chain retailers in the coffee busy may also appreciate their waste to be given to industrious gardeners.

  42. Angel Keplinger says:

    I am starting my first garden this year can I use the coffee grounds in it when I start. And any other good hint would be so helpful. Thank you and bless all

  43. Definitely believe that which you stated. Your favorite justification seemed to be on the internet the simplest thing to be aware of. I say to you, I definitely get irked while people think about worries that they just don’t know about. You managed to hit the nail upon the top and defined out the whole thing without having side-effects , people can take a signal. Will likely be back to get more. Thanks

Trackbacks

  1. [...] micro greens and then Actual Greens. I’m thinking I may top up the soil a little with some used coffee grounds, as I hear that’s helpful for leafy greens. I’m hoping (valiently?) to see some sprouts [...]

  2. [...] On her blog, Erica listed 5 of her favorite ways she used coffee grounds in her garden. [...]

  3. [...] Coffee Grounds by Northwest Edible Living [...]

  4. [...] 5 Ways To Use Coffee Grounds In The Garden [...]

  5. [...] To see supporting articles, please click here and here. [...]

  6. [...] February 18, 2013 by Erica · 60 Comments [...]

  7. […] …No more coffee grounds in the garbage – no, no, no. Erica, the Seattle chef turned gardener on NWedible.com, says that coffee grounds act like any other organic mulch – band – it has other advantages as well – like suppressing  fungal disease and detering slugs,  ( Five Ways to Use Coffee Grounds in the Garden). […]

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