Whether you are aware or not, putting used coffee grounds in your garden is a highly debated topic. Some people swear by using coffee grounds for the garden in their compost, or as mulch for their gardens. Others say it’s the worst thing you can do for your plants, so which opinion is correct? How do you know if you should – or shouldn’t – put used coffee grounds in your garden? We’ve researched the pros and cons for you, and break it down below so you can make the right decision on how to use coffee grounds in the garden.
Coffee Grounds as Mulch
Using mulch in your garden can be beneficial, but many people find the cost of mulch too expensive to turn into organic matter. Straw and compost can be used as mulch, but not many people have tons of straw lying around, and compost takes months to create. So it seems as though coffee grounds would be the perfect solution for gardeners in need of mulch. However, coffee grounds can actually harm the roots of seedlings by inhibiting growth if applied to thick. Also, coffee contains caffeine, which has been found to suppress the growth of plants. Coffee grounds are tiny particles that are prone to locking together and forming clumps.
These clumps can become a barrier to water and other nutrients that the plants need to absorb. So what is the answer regarding using coffee grounds as mulch? The solution is to mix coffee grounds with other organic matter such as leafmold or compost before using it as mulch. You can also rake coffee grounds into the top layer of soil so they can’t clump together. The key is to have variable particle sizes in your soil and mulch to promote good soil structure.
Coffee Grounds as Fertilizer
Coffee grounds contain several essential nutrients such as nitrogen, potassium, and phosphorus, along with micronutrients – all of which make using coffee grounds for plant mulch a great idea. The amount of nutrients in each batch of coffee grounds varies, but ultimately, coffee grounds can be used as a slow-release fertilizer. Sprinkle coffee grounds in a thin layer onto your soil to use as a fertilizer. Also, it has been reported that worms like coffee grounds and worms are a necessary part of the ecosystem that is any garden.
Coffee Grounds in Compost
There are two types of compost material: green and brown. Coffee grounds fall into the green category since they are a green material, which means they are rich in nitrogen. Other green materials are food scraps and grass clippings. All of these green materials contain magnesium, calcium, potassium, and other trace minerals. You can throw your coffee grounds, paper filter and all, into your green compost bin, but when it comes time to put the compost in the garden, you must mix your green compost with some brown compost. Brown compost material consists of items such as newspapers and dried leaves. The general rule is to have a 4-to-1 ratio of brown to green compost material.
Coffee Grounds as a Pesticide
Many people also swear that used coffee grounds in garden beds will get rid of slugs and snails that are damaging their plants. Though the reason is not apparent, whether it is the texture of the coffee grounds that the bugs don’t like or caffeine is bad for snails and slugs, the slimy creatures tend to avoid coffee grounds at all costs. The same has been thought for ants as well, but there isn’t really any science to back this up. The only way to find out if your garden will benefit from coffee grounds as a natural pesticide is to give it a try. If it works for your garden as a barrier to pesty insects, great. However, you should prepare a backup plan to exterminate the plants’ threats if the coffee grounds don’t work.
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