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How Can I Use Coffee Grounds as Fertilizer?

By Recyclebank |

Coffee grounds definitely should go back in the ground, but what about potted plants?

Dear Recyclebank,

I tried adding used coffee grounds to my house plants and had a mold issue. What did I do wrong? Also, can I use the actual coffee as fertilizer?

-Dawn R., Madison, WI


Coffee grounds are an excellent addition to compost piles and outdoor gardens, but they can be tricky when it comes to indoor container gardening. When mold appears on grounds in a compost pile, it is eventually consumed by bacteria and turned into compost — no big deal. In an indoor setting, mold is unsightly and can pose hazards to human health. Fortunately, there are a few strategies you can take to successfully add grounds to your indoor plants.

  • Reduce the amount and/or frequency of watering. A common reason for mold appearing on potted soil is excessive moisture. You may want to let the soil dry out a bit before adding grounds, especially if the grounds are already damp.
  • If applying to the surface of the soil, layer the grounds thinly. Grounds can be compacted, retaining moisture and preventing aeration. This can result in an ideal environment for mold growth.
  • Try mixing the grounds in with the top layer of soil. The variable particle size helps prevent compaction, thus improving drainage.

As for using the coffee itself as fertilizer, there seems to be little scientific evidence confirming its benefits but plenty of anecdotal evidence in the positive. Coffee is rather acidic, which can be beneficial to plants that thrive in acidic soil. However, it’s probably still a good idea to dilute any coffee you’re adding.


Oregon State University Extension Service
University of Illinois Extension


Do you add coffee grounds to the soil of your houseplants? Tell us if you’ve found success in doing so!

Share with Your Friends & Family
  • evelyn v. 19 days ago
    I started a veggie, fruit and herb garden. I have beautiful tomatoes, papaya, star fruit, spinach, scallions, mint, oregano, basil and chives. I love it.
  • evelyn v. 19 days ago
    I started a compost bin. Throw all of the coffee grinds, paper filters, leaves and fruit and vegetable scraps in. Works Great.
  • Barbara W. 25 days ago
    7 years ago, just re-dated. but hey at least we got the 5 points!
    I do the same with tea bags., I think it works.
    • Michael M. 25 days ago
      Barbra W. I know it does. I have 3 Aloe Vera plants, and an Ivey (about 15 feet long), that I put used, dried tea grounds in the soil, every other week. I also did this to several tomato plants, bell pepper plants, Jalapeno plants, and got bumper crops, of all of them.
  • Lorraine B. 25 days ago
    wow love this
  • Mark F. 25 days ago
    Coffee grounds and filters go in my compost pile
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