Are you wondering if it’s safe to use coffee grounds in your garden? You have to know how to use them properly!
When I began gardening, I had NO idea there would be controversy over different topics, and whether or not you should put coffee grounds in garden beds is a BIG one. Some gardeners say it helps their plants, while others say it is a TERRIBLE idea.
I’m of the mind that, typically, things are true from both sides. I’ve always sprinkled coffee grounds in my garden beds and never had a problem, but I wanted to investigate whether or not I should keep doing so.
I’m glad I did; I learned a lot, and I’m sharing that with you here!
Are Coffee Grounds Safe for Your Garden?
Yes, coffee grounds ARE safe for your garden if used properly. Even if you use them improperly, chances are they won’t kill your plants, but it could inhibit their growth slightly. That’s obviously not something you want to do.
Coffee grounds have nutrients that are valuable in your garden or compost pile. They’re a source of NPK – nitrogen, phosphorus, and potassium – three of the most important nutrients for garden beds. Assuming you use them in the proper ways, that means coffee grounds could help your plants grow to their maximum potential!
How to Use Coffee Grounds in Garden?
If you decide you want to use coffee grounds in your garden beds, you want to do so in the appropriate ways.
Coffee Grounds in Garden as a Mulch
One way you can use coffee grounds in garden beds is as a mulch, but the reality is that this can be a quite an expensive way to suppress weeds. However, many coffee shops will save grinds for you for free if you tell them you need it for your garden – they’re going to toss them anyway.
However, the question is – are grounds a safe mulch?
Some evidence suggests that applying thick layers of coffee grounds harm the roots of your plants by reducing and blocking growth. Coffee contains caffeine – that’s why we drink it! – and caffeine reduces plant growth.
Another problem is that grounds will clump together, potentially blocking water and nutrients from absorbing into the ground.
What’s the solution?
You can still use coffee grounds as part of your organic mulch, but I suggest mixing it with other materials. Mix it with your grass clippings, leaf mold, or compost. Another idea is to simply mix the coffee grounds into the top layer of your soil.
Also, avoid using excess amounts. Small amounts of coffee grounds as mulch won’t harm your plants, but if you use inches of it, it’s going to do more harm than good.
Coffee Grounds as a Fertilizer
When you’re researching ways to use coffee grounds in garden, you will come across suggestions to use it as a fertilizer. Some suggest to use coffee grounds right on the soil since they are a source of nitrogen.
However, they won’t immediately add nitrogen, so keep that in mind. They are a source of other essential nutrients like potassium and phosphorus, but it acts like a slow release fertilizer.
Using coffee grounds as a fertilizer has some benefits. It will increase the organic materials in the soil, improving the overall drainage in the soil and the aeration in the soil. Used coffee grounds aide microorganisms to help plants thrive by attracting earthworms.
All you have to do is sprinkle coffee grounds in a thin layer to use as a fertilizer, but you want to use too much because it will clump together.
However, are coffee grounds a safe fertilizer for your garden?
Yes and no.
Some gardeners suggest that coffee grounds may lower the pH balance, raising the acidity level of the soil. If you apply the grounds to acid loving plants, then that’s ok, but not all plants love acid.
Is there a solution?
The truth is that only fresh, unused coffee grounds are acidic. As long as you are using used coffee grounds in your garden, they have a neutral pH range. Typically, used coffee grounds have a near neutral pH range around 6.5.
Coffee Grounds in Your Compost
One of the best ways to use coffee grounds in garden is to compost them. Why not compost something that is going to end up in the landfill anyway?
When you add coffee grounds into your compost, you add extra nitrogen; it’s considered a green material. Tossing coffee grounds into a compost pile is no big deal, especially since coffee filters are compostable as well.
The only thing you should truly keep in mind is that these materials have to be balanced with brown – carbon – compost materials.
Coffee Grounds in Garden as a Pesticide & Other Unwanted Visitors
Do you have unwanted visitors to your garden?
Some gardeners say that coffee grounds can be used to keep away a number of pests and other garden visitors. The theory is that putting the ground around your plants will keep away slugs and snails because caffeine will negatively affect the pests. Others say that coffee grounds deter cats from your vegetable gardens.
Others say the same thing for ants, even though there isn’t a lot of hard evidence to support this way of deterring ants in the garden.
In general, you may find that coffee grounds works as a natural pesticide, but be ready with a different plan if they fail.
Feed Your Worms Coffee Grounds
If you have a vermicompost in your house, you can feed worms the coffee grounds. Worms actually love the grounds, and worm composting is one of the easiest options, even for apartment dwellers.
However, when using coffee grounds to feed your worms, be sure not to give them too many at once. They should receive one cup per week if you have a small worm bin. If you have extra grounds, applying the grounds to your garden soil will attract more earthworms.
Can Coffee Grounds Acidify Your Soil?
Not really, not unless you use a lot of fresh unused coffee grounds in your garden.
Fresh grounds are acidic, but most gardeners are going to brew their morning cup of Joe before spreading them around the plants. The acid in coffee beans is water-soluble, so at the end, they are more neutral than anything.
So, if you want to use coffee grounds to add acid to your soil, that’s not going to happen.
What Plants like Unused Coffee Grounds?
As I mentioned, unused coffee grounds are more acidic than used ones. So, if you plan to dump out a few good containers of Folgers, pick plants that like extra acid, such as:
The truth is you can use coffee grounds in your garden as a fertilizer, an organic mulch, or in your compost piles. However, be sure to avoid using too much and always pick used – not fresh – coffee grounds.
Do you use coffee grounds in the garden? Let me know in the comments!