If you are an avid coffee drinker, you probably throw away used coffee grounds from your coffee grinder every single day. But why throw them away when you can use the grounds in your garden to improve soil and plant health? Whether you’re looking to reduce waste or to make nutrient-rich compost, here are 4 ways to utilize used coffee grounds in your garden:
Used coffee grounds as a mulch
Mulching helps preserve moisture and is very beneficial for soil fertility and health. However, mulch is particularly hard to compost in large quantities, especially at a decent price. The solution? Used coffee grounds!
Ideally, you would mix the used coffee grounds with other organic matter that can be used as mulch because using coffee grounds alone around plants can affect their development. This can be due to the caffeine content in the coffee grounds, as caffeine can inhibit the growth of some plants. Also, it is important to note that some plants are more sensitive than others so it is best to experiment first.
To be safe, it is best to avoid spreading used coffee grounds directly on plants or around seeds to be sure germination and growth are not affected.
If you mix the coffee grounds with other organic matter such as leaf mould, your garden plants will be safe. Most importantly, the coffee grounds won’t stick together and won’t form a barrier that prevents water from penetrating the soil.
Many people believe coffee modifies the soil’s pH but not all coffee grounds are acidic and even if they are, the acidity is transferred to your cup of coffee during brewing so the leftover grounds are not as acidic as the fresh grounds.
Used coffee grounds as fertilizer
Used coffee grounds also make a great slow-release fertilizer. Coffee grounds contain essential nutrients, such as phosphorus, nitrogen, and potassium so they can increase soil fertility. Additionally, coffee grounds can absorb heavy metals that can contaminate your garden’s soil.
To use the coffee grounds as fertilizer, sprinkle them sporadically onto the soil. They will feed the soil with important minerals and micronutrients and attract worms that will provide a more stable soil structure.
If you prefer the process of vermicomposting, the good news is that the worms love coffee grounds so, instead of throwing away used coffee beans, you can add them to your worm bin.
Used coffee grounds in your compost
Since they are great organic material, you can use coffee grounds in your compost as well. However, despite their colour, it is important to treat coffee grounds as “green” compost matter because they are nitrogen-rich. It is important to add enough “brown” materials like dried leaves or wood clippings to balance out the compost. Brown compost materials are rich in carbon.
Adding compost to your garden can significantly help the soil and, as a result, the health of your plants. And, truth be told, compost made with coffee grounds is richer in nutrients and better quality than the compost made with just waste.
Used coffee grounds as a natural pesticide
Plants that are vulnerable to slug damage can also benefit from your used coffee grounds. Generally speaking, slugs tend to avoid crossing a barrier of coffee grounds, either because caffeine is damaging for them or because the texture of the coffee grounds is too abrasive for their soft bodies.
Caffeine is also highly toxic for insects so sprinkling coffee grounds around the garden can also deter mosquitoes and fruit flies.
Bottom line
Since coffee grounds are nutrient-rich organic matter, they are a worthwhile addition to your compost and they can improve your soil. Moreover, coffee grounds may act as a pesticide, keeping slugs and insects away from your plants and can also be used as a slow-release fertilizer or even mulch.