The Common Mistake To Avoid When Using Coffee Grounds As Fertilizer In The Garden

One unexpected use for coffee grounds around your home that actually makes a huge difference is to add them to your garden soil. It makes total sense, considering they're a material you have available for free that contains soil-healthy nitrogen, and this way you're keeping them out of the landfill. However, be warned: simply throwing a load of coffee grounds onto the ground and calling it a day isn't always the best thing to do, not from your plants' perspective anyway.

The one thing you should never do with coffee grounds in your garden is pile them on top of the soil like a thick mulch. Piled on thick, coffee grounds will clump together to form a dense layer that doesn't allow water through, so your plants will seem happy at first, but slowly their roots will begin gasping for water. In large enough amounts, coffee grounds could stunt the growth of your plants. And fresh grounds are an even bigger no-no, as they are too high in acidity and caffeine, kind of like giving your plants a caffeine overdose. 

Don't give up on reusing coffee grounds yet; they can be useful in the garden, you just need to know how to use them. They're kind of like a seasoning for your soil, so you want to sprinkle them on or rake them in as opposed to simply dumping a pile of them around your plants as-is. It takes a bit more effort this way, but the results will pay off.

To really get the benefits of coffee grounds, you want to blend them into the soil or into your compost, not blanket them on top of the soil. It is recommended to use about 20% coffee grounds in your compost mix, ideally balanced out with some carbon-rich materials like dried leaves or straw. From there, coffee grounds act as a "green" material that contributes nitrogen to the compost, a key plant nutrient. The finished compost will feed the microbes that are essential to soil health. And according to research, coffee grounds may also help suppress certain fungal diseases, which is a great bonus.

You can also use them as part of a mulch blend, in small amounts. Simply mix them in with other mulch materials like bark, and your plants can get a slow trickle of the coffee grounds' nutrients. Or sprinkle a very thin layer around acid-loving plants, something to consider if you're caring for blueberry plants, azaleas, or rhododendrons. However, while coffee grounds are acidic, used grounds are closer to pH neutral, so don't fully rely on them to acidify soil. Finally, an essential step is to use the brewed coffee grounds once they've dried out, not grounds that have just been brewed and are still loaded with water. Coffee grounds, reused with consideration, can help build soil structure and feed helpful microbes, but they need to be used properly in order to reap the benefits.