How to Use Coffee Grounds for a Better Garden

Before you buy expensive chemical-based fertilizers, think about fertilizing your garden with the damp grounds from your morning cup of coffee. Did you know that old coffee grounds can be mixed in with your compost or applied directly to the soil to reinvigorate your garden?

Mix into Compost

Coffee grounds are nitrogen-rich, organic plant matter, making them a 'green' composting material. As a result, they're an excellent complement to carbon-rich, 'brown' compost sources like dried leaves and paper. You can even add shredded used coffee filters as another source of carbon-rich material. Work coffee grounds into your compost just as you would any other organic material. When decomposed properly, coffee grounds can supply critical nutrients - like nitrogen, phosphorus, potassium, magnesium and copper.

Incorporate Directly into Soil

If you don't have a compost pile, you can apply dry, used coffee grounds directly into your garden soil. Always be sure to incorporate the grounds. If left to dry out on the soil's surface, they can actually repel water the same way peat moss does. And they can get moldy if dumped out in clumps on top of the soil.

  • STEP ONE: Start with acid-loving plants first. Coffee grounds are great for acid-loving plants like tomatoes, blueberries and avocados, as well as azaleas, evergreens, poinsettias and camellias. They work well with other plants too, but remember that each plant may require a different amount.
  • STEP TWO: Add grounds gradually, starting with about 1 tablespoon of grounds surrounding each plant. Lightly work them into the soil each week, taking note of how each plant reacts.
  • STEP THREE: Continue to add more grounds weekly until plant health no longer seems to be improving.
  • STEP FOUR: If needed, you can also dig damp coffee grounds into heavy alkali soil to break it down and attract earthworms, effectively improving soil aeration.

More about coffee grounds:

  • Used coffee grounds aren't as acidic as one would think. The acid in coffee is water-soluble, so most of the acid is leached out during brewing.
  • In some cases, coffee grounds have been shown to repel slugs and snails.
  • Using coffee grounds as fertilizer can also improve soil structure.
  • Coffee grounds are a great nitrogen source, with a carbon to nitrogen ratio of 20:1.
  • They've also been known to improve water retention and even increase plant yield.
  • In farming, coffee grounds have been found to produce large vegetables with resistance to insect infestations.
  • Many gardeners have found mixing coffee grounds with their carrot seeds yields a healthier crop and deters pests.


The Dirt from Troy-Bilt®, July/August 2014