Sasha CampbellIf you enjoy organic gardening, used coffee grounds can benefit your garden in many ways. You can add them to compost, use them around certain plants, and more.
How to Use Coffee Grounds in the Garden
Below, we will expand on the most common uses for coffee grounds in the garden.
1. Add to Compost
By composting coffee grounds, you’re in effect adding nitrogen to the compost [1]. It works well with other organic materials to make rich, healthy compost.
To compost coffee grounds, add them to your compost bin and mix them well. Used coffee grounds are a “green” compost material because they are rich in nitrogen.
Mix them with plenty of “brown” materials, such as dried leaves, straw, or shredded paper. Try not to let coffee grounds make up more than about one-fifth of your compost pile.
Coffee filters can also be composted, and it might be a good idea to ask the local coffee shop or café for any leftovers.
2. Fertilize with Coffee Grounds
Used coffee grounds add small amounts of nutrients to the soil over time [2]. They work best when mixed into compost or lightly worked into the soil.
To use coffee grounds as fertilizer, sprinkle them lightly over the soil around the base of the plant and leave them in place. Avoid spreading them in thick layers, as they can form a crust that prevents water from reaching the soil.
You can also make homemade coffee grounds tea for your plants. Just add two cups of used coffee grounds to five gallons of water. Then, let it steep overnight.
Use the strained liquid to water plants as a mild soil booster. However, do not use it every time you water your plants.
3. Repel Slugs and Snails
Some gardeners use coffee grounds around plants to discourage slugs and snails. While the grounds themselves may provide only limited protection, caffeine has been shown to affect these pests.
To use coffee grounds as a slug repellent, sprinkle some on the soil around the affected plants.
You can also make a caffeine spray for slugs and snails from freshly brewed coffee. Combine one part brewed coffee with nine parts water [3]. Spray it directly on the pests and plant foliage.
4. Cat Repellent
Coffee grounds may help deter cats, as many dislike the smell of coffee [4].
Therefore, sprinkling fresh, wet coffee grounds in the areas cats use as litter trays may deter them. You can also sprinkle some around the borders of your garden.
Some gardeners also use coffee grounds to try to discourage rabbits and squirrels, although results vary.
5. Grow Mushrooms
Another way to use coffee grounds for gardening is to grow mushrooms.
Growing mushrooms can be tricky. However, oyster mushrooms grow well on coffee grounds [5].
Used coffee grounds have nitrogen and nutrients such as potassium, magnesium, iron, and phosphorus. Moreover, they are partially sterilized in the brewing process.
6. Add to Your Worm Bin
Unlike cats, slugs, and snails, worms love coffee grounds.
Earthworms enjoy small amounts of used coffee grounds mixed into their bedding. Many gardeners believe the gritty texture helps worms digest food.
Therefore, add some used coffee grounds to your worm bin. However, avoid adding too many at once because they can make the bin too acidic.
7. Use as a Mulch
Composted coffee grounds make a better mulch than fresh grounds.
Spread a thin layer around plants or mix them with other mulch materials, such as leaves or wood chips. Avoid using thick layers because they can become compacted and keep water from reaching the soil.
Acid-loving plants can benefit from compost containing coffee grounds, as it adds organic matter and nutrients. However, used coffee grounds do not greatly lower soil pH.
8. Repel Ants
Some gardeners use coffee grounds to help discourage ants rather than kill them. They believe ants avoid the smell of coffee grounds, although scientific evidence is limited.
To give it a try, sprinkle coffee grounds into ant nests and around doorways.
Plants That May Benefit from Composted Coffee Grounds
These plants may benefit from compost that contains coffee grounds or from small amounts of composted coffee grounds mixed into the soil.
Some fruit trees and vegetables that may benefit from compost containing coffee grounds include:
- Blueberries
- Carrots
- Elderberries
- Peppers
- Cucumbers
- Tomatoes
- Sweet potatoes
- Radishes
Other plants that benefit from coffee grounds include flowers and shrubs such as zinnias, camellias, azaleas, rhododendrons, and hydrangeas.
Some houseplants and other potted plants may also benefit from compost containing coffee grounds.
Takeaway
Used coffee grounds can be a helpful addition to your garden when used properly. They work best in compost or in small amounts mixed into the soil.
Instead of throwing them away, reuse them to naturally improve your garden.
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