You don’t have to be a coffee drinker to enjoy the benefits of using the grounds in your garden. Many local coffee shops will sell or give away used coffee grounds just for gardeners’ use. Used coffee grounds contain nitrogen, potassium, and phosphorus, which are good nutrients for your soil. Plus, it feels good to reuse something that would otherwise just sit in a landfill.
Think of the grounds as a periodic fertilizer. You can take the grounds and simply sprinkle them directly onto the soil. Then disperse them using a rake or lightly work them into the soil enough so that the grounds won’t harden on top and not seep through. Make sure you don’t rinse the grounds first. You want fresh, unwashed coffee grounds to get the right effect. You can also make a liquid to pour into the soil. A good ratio is about two cups of coffee grounds with five gallons of water, let it sit overnight, then pour away this liquid black gold.
Do All Plants Like Coffee Grounds?
Because coffee is acidic, you’ll want to use the grounds for acid-loving plants in particular. The grounds will lower the pH level of your soil, which causes it to be more acidic. (Read our other blog here for more information on pH levels.) Plants and flowers such as azaleas, roses, hollies, hydrangeas, and lilies will thrive with coffee grounds. However, tomatoes or rhododendrons may be a little more sensitive to the acidic nature and develop brown leaf tips if they come in contact with the grounds. Avoid applying grounds when your plants are still seeds, as it can affect germination. Give them some time to grow for a bit first. Coffee grounds can also be good for grass. It helps grass look greener and grow longer, which is certainly a priority here in Utah. Experts suggest you take some caution with using grounds. Too much and you can actually burn your plants. Using the ratio above (two cups of grounds to five gallons of water) should protect your plants from too much nitrogen.
Deter Bad Bugs
Many gardeners use coffee grounds as a natural bug repellant. They will help keep slugs and snails away because of the abrasive nature of the grounds. However, they will help attract earthworms, which are beneficial to your plants. The earthworm is the single most beneficial organism for soil health. They decompose organic matter, increase soil aeration and infiltration, and encourage water movement and nutrient cycling. Worms love coffee grounds, so welcome them by using them wherever applicable.
If you don’t have coffee grounds in your house, visit some local coffee shops and you’ll likely see some bags for sell at a bargain. If you don’t, simply ask the barista. Many shops love sharing their grounds with the community because they understand the many benefits. If you want to get started using grounds in your garden but you’re still nervous about adding too much nitrogen, come in and talk to one of our specialists to get advice for your particular garden situation.