Grounds in the Garden

Add Coffee Grounds to Your Compost

Adding coffee grounds to your garden and compost is a quick, easy way to add nutrients and organic matter to your soil.

Coffee grounds ready for composting

Coffee grounds can be a source of nitrogen. Sunset Magazine did an analysis years ago and found that the nutrient ratio was the following:

Nitrogen: 2.28 percent
Phosphorus: 0.06 percent
Potassium: 0.6 percent

You can add grounds directly to the soil by digging them into six inches of soil. You can also sprinkle them on top of soil as long as you are careful not to form a thick crust.  Or, put grounds into your compost bin – they’ll heat everything up in no time!

Benefits of Coffee Grounds*
  • Coffee grounds contain the three major nutrients—nitrogen, phosphorus, & potassium.
  • Grounds also contribute important micronutrients—magnesium, copper, and calcium— not typically found in synthetic fertilizers.
  • Coffee grounds won’t burn plants, pollute groundwater, or kill soil organisms that are part of a healthy ecosystem.
  • Adding grounds (up to 25% the volume of your soil) will improve soil structure in the short and long term.
  • Only a small percent of the nitrogen found in coffee grounds can be used by plants immediately. Over time, microorganisms break down the organic matter, converting suspended nitrogen into a useable form. This creates a steady, slow release fertilizer that plants love.
  • Coffee grounds neutralize odor, discourage visits from mischievous cats, and repel garden pests such as ants, snails, and slugs.
  • Grounds have a slightly acidic pH (6.2-6.8), which many plants appreciate in Austin’s alkaline soil.
  • With a carbon to nitrogen ratio of 24:1, grounds are compostable without any other additives.

This fact sheet examines the science behind the use of coffee grounds in gardens and landscapes and provides recommendations for home gardeners to use coffee grounds appropriately.

Oregon State University Extension studies coffee grounds for use in the home garden. Here is their post about how to add coffee grounds appropriately:

*Sunset Magazine: The Starbucks coffee compost test (, accessed 03/31/21). Research conducted by Soil and Plant Laboratory Inc., Bellevue, WA.

Additional Resources for Soils and Composting

Soils and Composting for Austin
The Real Dirt on Austin Area Soils
Compost Brings Life
Don’t Bag it, Compost it!
Leaf Management Plan

Print Friendly, PDF & Email

Comments are closed.