Whether you make your cup of coffee daily or you have noticed your local coffee house has started to put out bags of used coffee, you may be wondering about composting with coffee grounds. Are coffee grounds as fertilizer a good idea? How do coffee grounds used for gardens help or hurt? Keep reading to learn more about coffee grounds and gardening.
Composting Coffee Grounds
Composting with coffee is a great way to make use of something that would otherwise end up taking up space in a landfill. Composting coffee grounds helps to add nitrogen to your compost pile.
Composting coffee grounds is as easy as throwing the used coffee grounds onto your compost pile. Used coffee filters can be composted as well.
If you will be adding used coffee grounds to your compost pile, keep in mind that they are considered green compost material and will need to be balanced with the addition of some brown compost material.
Coffee Grounds as Fertilizer
Used coffee grounds for gardening does not end with compost. Many people choose to place coffee grounds straight onto the soil and use it as a fertilizer. The thing to keep in mind is while coffee grounds add nitrogen to your compost, they will not immediately add nitrogen to your soil.
The benefit of using coffee grounds as a fertilizer is that it adds organic material to the soil, which improves drainage, water retention, and aeration in the soil. The used coffee grounds will also help microorganisms beneficial to plant growth thrive as well as attract earthworms.
Many people feel that coffee grounds lower the pH (or raise the acid level) of soil, which is good for acid loving plants. This is only true for unwashed coffee grounds though. Fresh coffee grounds are acidic. Used coffee grounds are neutral. If you rinse your used coffee grounds, they will have a near neutral pH of 6.5 and will not affect the acid levels of the soil.
To use coffee grounds as fertilizer, work the coffee grounds into the soil around your plants. Leftover diluted coffee works well like this too.
Other Uses for Used Coffee Grounds in Gardens
Coffee grounds can also be used in your garden for other things.
- Many gardeners like to use used coffee grounds as a mulch for their plants.
- Other uses for coffee grounds include using it to keep slugs and snails away from plants. The theory is that the caffeine in the coffee grounds negatively affects these pests and so they avoid soil where the coffee grounds are found.
- Some people also claim that coffee grounds on the soil is a cat repellent and will keep cats from using your flower and veggie beds as a litter box.
- You can use coffee grounds as worm food too if you do vermicomposting with a worm bin. Worms are very fond of coffee grounds.
Using Fresh Coffee Grounds
We get lots of questions about using fresh coffee grounds in the garden. While it’s not always recommended, it shouldn’t be a problem in some situations.
- For instance, you can sprinkle fresh coffee grounds around acid-loving plants like azaleas, hydrangeas, blueberries, and lilies. Many vegetables like slightly acidic soil, but tomatoes typically don’t respond well to the addition of coffee grounds. Root crops, like radishes and carrots, on the other hand, respond favorably — especially when mixed with the soil at planting time.
- The use of fresh coffee grounds are thought to suppress weeds too, having some allelopathic properties, of which adversely affects tomato plants. Another reason why it should be used with care. That being said, some fungal pathogens may be suppressed as well.
- Sprinkling dry, fresh grounds around plants (and on top of soil) helps deter some pests same as with used coffee grounds. While it doesn’t fully eliminate them, it does seem to help with keeping cats, rabbits, and slugs at bay, minimizing their damage in the garden. As previously mentioned, this is thought to be due to the caffeine content.
- In lieu of the caffeine found in fresh, unbrewed coffee grounds, which can have an adverse effect on plants, you may want to used decaffeinated coffee or only apply fresh grounds minimally to avoid any issues.
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Coffee grounds and gardening go together naturally. Whether you are composting with coffee grounds or using used coffee grounds around the yard, you will find that coffee can give your garden as much of a pick me up as it does for you.