Excellent article from friend and colleague, Ron Wilson of Natorp’s Garden Outlet.
Why use coffee in the garden
If you thought coffee grounds were only for acid-loving plants oh no, it can be applied to just about anywhere and trust me, the plants and the earthworms are going to love you for it! Spent coffee grounds, if used properly (and in moderation), are an excellent way to wake up the plants in your garden. At Starbucks, coffee shops, at home, or at the coffee machine at work, spent coffee grounds are generated every day, and FREE for you to use in your garden, adding all its benefits, as well as reducing the amount of coffee waste going to landfills. And, they make the garden smell good!
Benefits of reusing Coffee Grounds:
Great source of organic matter added to the soil, whether in-ground or in containers.
Helps to improve texture, soil structure, moisture retention capabilities, and fertility of the soil.
Low source of nitrogen, as well as low levels of phosphorus, potassium, calcium, magnesium, copper and sulfur. (Carbon-Nitrogen ratio of about 20:1)
Combined with brown material (leaves, straw, etc.) they generate heat which helps speed up the composting process. Great addition to your compost pile! -Used coffee grounds (over time) may help lower the soil pH (grounds usually average around 6.2). Test the soil for proper pH levels.
Appear to suppress some common fungal rots and wilts in the soil. -Worms love coffee grounds!
Possible ways to use coffee grounds for your plants and soil:
- Add the used coffee grounds directly to the soil surface (landscape, flower and vegetable gardens) as a soil amendment, and till them in. On study suggested up to 6 pounds per 100 sq. ft.
- Sprinkle with plants and water it in. Azaleas, hollies, hydrangeas, evergreens, blueberries (acid loving plants) especially appreciate a shot of coffee grounds. But they can be used in all areas of the landscape, lawn, and garden. Rose growers have been using coffee grounds around their roses for years! Side dress plants with up to 1/2 inch of used coffee grounds; re-apply after the grounds de-compose. Or sprinkle into mulch, over the lawn, etc. Be sure to water afterward.
- Used coffee grounds have been reported to act as a natural ‘soil’ insect repellent, including slugs and ants. Some folks have also had success with coffee grounds repelling cats from the mulch beds.
- Sprinkle of few grounds around the top of the soil in your indoor plants, or mix in with the potting soil when repotting. -Add them to your compost pile (10-20% of the pile) – they help speed up the composting process. Adding them to the compost or mixing in the soil – earthworms will love you for it. And the more worms, the better your soils will be.
- Also, use them for vermicomposting (combined with other worm-feeding materials). (Paper coffee filters can be composted as well.) -Home brew liquid fertilizer, using about ½ to 1 pound of wet used grounds in 5 gallons of water. Let sit for 24 hours and apply around plants.
Plants that don’t like coffee grounds: White / red clover, alfalfa, Italian ryegrass, Chinese mustard, asparagus ferns, geraniums, and inch plants (seed included).
Even if you don’t drink coffee, take advantage of the FREE used coffee grounds at the office or local coffee shops and share them with your soil, earthworms, and plants.