Are coffee grounds good for your garden? If you have been gardening for a while, you have probably heard evidence for both sides of this argument. Instead of throwing them out, maybe next time, try to use coffee grounds for something related to your garden.
There are many ways that you can include coffee grounds in your garden. If you make sure to use the correct techniques, the coffee grounds will almost certainly improve the growth of your plants.
Coffee Grounds in Compost
If you have a compost pile, your used coffee grounds could be a perfect addition. Firstly, it is an excellent way to make use of something that would otherwise end up in a landfill. Although the grounds themself are brown, they are considered ‘green’ compost material, which means that they are rich in nitrogen.
If you do this, make sure you have a 4 to 1 ratio of brown to green compost materials. Brown materials, such as coffee filters or sawdust, are rich in copper. Overall, the coffee grounds should take up 10-20% of the total compost volume.
In one study, it was shown that when 25% of the compost material was coffee grounds, the compost sustained a 140 to 160 degrees Fahrenheit temperature for up to two weeks. Another study found that the higher the percentage of coffee grounds was, the lower the greenhouse gas emissions were.
If there are worms in your compost pile, they will love it if you add coffee grounds. Just like most humans, worms enjoy the taste of the coffee. They also need to eat gritty food to help their digestive system, and coffee grounds are perfect for this task.
However, do not use too much, as it will bother them. One cup per week in your worm compost will be the right amount. However, do not put the cup in all at once; you should spread it out over the course of the week. Overall, compost that has been enriched by using coffee grounds is more abundant in nutrients than regular compost.
Using Coffee Grounds as Fertilizer
By fertilizing your plants with coffee grounds, it is adding organic materials to the soil. This has been shown to improve drainage, water retention, aeration, and soil structure, and attract micro-organisms that help plant growth. For all these benefits to happen, you must use used coffee grounds.
Fresh, unwashed grounds will lower the soil pH, as they are acidic and have a pH of about 5. Used grounds have a near-neutral pH of 6.5, which will not affect the soil in any way. However, you can use fresh grounds for acid-loving plants like azaleas, hydrangeas, blueberries, lilies, radishes, carrots, or rhododendrons.
Using fresh coffee (How long do coffee beans last?) grounds has also been found to be able to suppress weeds. If you are looking to shift the soil pH, you should bury the fresh grounds 7 to 8 inches deep in the soil.
When using leftover diluted coffee, you should work the grounds into the soil around the plant. If the grounds are laid too thick on the soil, their fine particles will lock together. This will create a barrier that resists water, and your plants will die from dehydration.
To prevent this, you can do a few things. Firstly, you can mix the grounds with compost and put the grounds around your plants. If you do not have a separate compost pile, you can rake the used coffee grounds into the soil to break up the particles. Another thing you could do is use a thin layer of grounds covered with a thick layer of organic matter.
You can also use your coffee grounds to make a liquid fertilizer. You will need to mix up 2 cups of grounds with 5 gallons of water and let it steep for a few hours or even overnight. Afterward, you can spray it on your plants to help them grow.
You should be aware that used coffee grounds contain high amounts of nitrogen, which might be too much for some plants. The nitrogen helps most plants grow larger and more robust, but it can be harmful to some plants that grow flowers or fruit. Tomatoes, however, need nitrogen to be healthy, since it helps their roots grow.
It is also beneficial to rose bushes because it loosens the soil texture and gives the roots more room to grow. Using coffee grounds has also been found to stall root growth in young plants. So, it is all about finding which of your plants react well.
Another thing you can do with this fertilizer is to use it on your lawn. You will have to modify it a little bit so that you mix 1/2 cups of coffee grounds with 5 gallons of water. After that, you should be able to spritz it all over your lawn, or just in places where the grass isn’t growing as well as you would like it to.
In addition to nitrogen, used coffee grounds also contain potassium, phosphorus, magnesium, and calcium. All of these are helpful for the plants in your garden to grow. Putting the coffee grounds in your garden does not immediately add these substances to your plants.
This is the reason that coffee grounds are suitable for use as a slow-release fertilizer. Because of this, the nutrients will continue to be released into the soil until the next time you decide to fertilize your plants. The grounds can also be mixed with eggshells to create a better fertilizer to spread around the plants in your garden.
Coffee Ground Mulch
Mulch is a layer of material that is applied to the surface of the soil. Another way of using your coffee grounds from your morning coffee is to turn it into mulch. Using the coffee grounds for this gives texture to the soil, and is excellent for sugar beet seeds, cabbage, and soybeans.
To do this best, you should put 1/2 inch of grounds over the existing soil, and put wood-chips over the grounds. Adding coffee to your garden mulch will help your plants grow to their full potential.
In addition to this, organisms will slowly break down the coffee grounds present in the mulch. This will allow the coffee grounds to slowly release the nitrogen that they carry into the new soil. Adding coffee grounds has been shown to keep slugs away from your fresh mulch. The earthworms that are part of the mulch will help combine the coffee grounds and the rest of the mulch, which will improve the soil and therefore improve the growth of your plants.
Overall, coffee grounds create a great mulch. They are more organic than some ingredients that could be present in your mulch. The earthworms will break them down, and they will decompose themselves, slowly releasing all the nutrients that they have.
You will need to combine the coffee grounds with other mulch since the grounds by themself will reduce the amount of water and air available to your plants. In addition to harming your plants, piling coffee grounds onto the soil will also cause mold. To ensure that none of these problems occur, you can mix the coffee grounds with the regular mulch. You could also put about a half-inch of the used coffee grounds over the regular organic mulch.
Using Coffee Grounds as Pesticide
While trying to grow plants, you will almost certainly want your garden to be clear of all pests. Slugs and snails are just an example of the many creatures that can wreak havoc on your plants.
By adding coffee grounds to your garden, it is shown that they will stay away. It is not clear why they tend to dislike the coffee grounds. Studies show that it is either because their skin reacts badly to the abrasive texture of the grounds or it has something to do with the caffeine present in the coffee grounds.
After spraying slugs with caffeine, most of them died. However, most used grounds do not have enough caffeine to kill the slugs, just to aggravate them.
In addition to slugs, coffee grounds in your garden also keep cats away. Many gardeners complain about cats that come, and either use the garden as a litter box or dig up their plants. By putting coffee grounds around your plants, you might prevent the cats from ruining your garden. They have been found to dislike the strong smell of coffee, and have stayed away from gardens that use coffee grounds as fertilizer.
In addition to these pests, coffee grounds have been found to keep many other things away from your plants too. Coffee grounds are anti-microbial, meaning that they will prevent things like Fusarium, Pythium, and Sclerotinia from harming your plants. It has also been found to stop E. Coli from invading your garden. Overall, these used coffee grounds are a natural way to keep away a plethora of things, also including mosquitoes, fruit flies, and beetles.
Which Plants Do and Do Not Like Coffee Grounds?
Some gardeners will say that coffee grounds should only be applied to acid-loving plants like azaleas or rhododendrons. While most used coffee grounds do not contain as much acid as fresh ones, it is still present and could potentially be harmful to your plants. If you plan to only use the coffee grounds on these types of plants, then there are many seeds that you can plant.
In vegetable gardens, you should be able to plant sweet corn, cucumbers, broccoli, beans, squash, onions, tomatoes, parsley, potatoes, peppers, radishes, basil, eggplant, and turnips. You could also plant fruits like cranberries, huckleberries, and blueberries, thimbleberries, gooseberries, and elderberries.
Using coffee grounds as fertilizer has been found to deter the growth of flowers in most flowering plants, but some thrive in a more acidic environment. These include azaleas, mountain heather, camellias, daffodils, hydrangeas, and nasturtiums.
Understanding Soil pH
The pH of your soil is vital to know when you are planning on using coffee grounds as fertilizer. Acid-loving plants will thrive in acidic soils. Any land with a pH below seven is considered acidic, and dirt with a pH above seven is described as alkaline soil. Soils with a pH of or very near 7 are neutral. A soil with a pH of 4 is ten times more acidic than dirt with a pH of 5.
Acidic soils will usually contain manganese, soluble iron, and aluminum, which is why many plants do not thrive in acidic soil. Alkaline soils contain higher concentrations of calcium and magnesium.
If you are looking to test the soil’s pH, there are ways you can do it pretty simply. There are many soil pH testing kits that you can buy at gardening stores or online. If you do not want to use a formal kit, you will need to collect samples from the different parts of your garden that you want to test and mix them together. All you need is a pH meter, and you’ll be able to check the soil’s pH around all your plants accurately.
As mentioned before, you can lower the pH of the soil (make it more acidic) by putting fresh coffee grounds 7 to 8 inches deep in the soil. There are ways to raise the pH of the soil (make it more alkaline), as well. One way to do this is to sprinkle finely ground limestone onto the soil around your plants during spring.
Another thing you can try is spread wood ash over the soil in your garden. This will raise the pH because wood ash is a good source of magnesium, calcium, aluminum, phosphorus, and potassium. Finally, you can also add dolomite to add calcium and magnesium to your soil.
Final Thoughts
In short, if you use coffee grounds you can do something good for your garden. But, you have to know what you’re doing.
Using too many coffee grounds or using them around plants that don’t work well with acidic soil will not work well. Start with small amounts of coffee grounds that you mix into your compost pile for use in your garden.
It can be of great help to determine the pH level of your soil before starting to use coffee grounds. If your dirt is already acidic then you might want to consider not to add coffee grounds in the compost bin. It will also help you understand where to use the grounds and where to hold back based on the alkalinity or acidity of your soil as well as the needs of the plants in that particular area of your garden.
A few grounds spread here and there in the garden will also help to keep slugs and snails at bay without using harsh and damaging chemicals. Follow the instructions above to mix the grounds with your organic matter and compost to create a healthy and pest-free environment for your garden!
