I've visited a site where a raised bed was ruined by too much coffee grounds. Like most kitchen waste, it is a fine amendment for the garden, but like anything else, coffee grounds can be overdone.” Contrary to popular belief, it's a myth that coffee grounds are acidic and will lower the pH of the soil.
She recommends that grounds make up no more than 15 to 20% of the total compost volume. Because they are acidic, coffee grounds make good acid mulch. Of course, too much of anything is just too much, so apply coffee grounds in limited amounts. Kit recommends a layer no thicker than half an inch.
Coffee grounds are highly acidic, they note, so they should be reserved for acid-loving plants like azaleas and blueberries. And if your soil is already high in nitrogen, the extra boost from coffee grounds could stunt the growth of fruits and flowers.
In most cases, the grounds are too acidic to be used directly on soil, even for acid-loving plants like blueberries, azaleas and hollies. Coffee grounds inhibit the growth of some plants, including geranium, asparagus fern, Chinese mustard and Italian ryegrass.
Another way to recycle leftover used coffee grounds is sprinkling them on top of your potting soil. If you plan to test out this method, do so sparingly. Avoid creating a thick layer. Used (and fresh) grounds can lock together and create a barrier to water penetration and air circulation.
How Often Should You Add Coffee Grounds to Plants? You can fertilize houseplants an average of 7 to 10 days in a row, but no more, as there is a risk of over-acidification of the soil. A cup of ground coffee should be added to the compost once a week.
It's okay to water plants with leftover coffee or to add coffee grounds to the compost pile but learning when and why to use coffee in the garden will protect your plants. Only use black, unflavored coffee with this method to offer plants a source of nitrogen which can fertilize certain indoor and outdoor plants.
Compost coffee grounds for a vegetable garden instead of using them directly. Remember, coffee grounds are not good for tomatoes or seedlings. Get a soil test, especially if your plants are not thriving or you want to change the acidity of the soil.
A: Most insects do not like the strong smell of coffee or the other essential oils you may add to your mixture or spray solution. By spreading coffee grounds throughout your yard, you are helping to fight off other bugs and pests!
Coffee Grounds to Deter Pests
Coffee grounds are commonly used to keep animals including slugs, snails, rabbits and fire ants from eating plants in the garden, and to keep cats from treating garden beds like litter boxes.
Coffee's bitter compounds are responsible for its repelling effects. These compounds make the coffee unpalatable to rats and mice. They will avoid areas where there is the use of coffee grounds.
Fresh grounds, and caffeine in general, have allelopathic properties. This can stunt plant growth and do more harm than good. Some people suggest using decaf grounds, both for new and used grounds.
The smell of coffee is repulsive to many bugs and will keep them away from treated areas. Coffee grounds can be used fresh or used, but unused coffee grounds are more effective at repelling pests. The smell of burnt coffee is also effective at repelling pests.
Coffee grounds take three to four months or more to decompose, depending on the soil microbial activity and health. The more microbial activity of the soil, the more quickly coffee grounds decompose.
A general guideline is called the "Golden Ratio" - one to two tablespoons of ground coffee for every six ounces of water. This can be adjusted to suit individual taste preferences. Check the cup lines or indicators on your specific brewer to see how they actually measure.
While it's true that your coffee will taste stronger if you add more grounds, it may also begin to taste bitter. So, the best way to get a good strong cup of coffee is to focus on a good dark roast. You'll also want to use the right grind.
Roaches are repelled by ground coffee. In fact, putting some ground coffee down in the corners or windowsills of your kitchen can actually help keep them insects away.
Coffee Grounds
Not only do coffee grounds smell good, but they also work wonders when it comes to warding off unwelcome guests such as spiders. Simply sprinkle some used coffee grounds near entry points and other problem spots throughout the house for extra protection.
Fact: Fruit flies are attracted to and feed on decaying fruits and vegetables, drinks (including beer and wine), spills, coffee grounds, drains, trash cans, dirty mops, towels, damp clothing, moist pet food and indoor houseplants. If it's damp and remotely edible, fruit flies and their larvae will use it.
Coffee grounds contain around 2% nitrogen as well as varying amounts of phosphorus and potassium which are all very important for the growth of tomato plants.
Dr. Chalker-Scott recommends against using pure coffee grounds as mulch. Instead, try using a thin layer (no more than half an inch) of coffee grounds and cover with a thicker (four inches) layer of coarse organic mulch like wood chips.
Which plants shouldn't you try this with? Don't add eggshell fertilizer to plants that prefer acidic soil, like blueberries. Ericaceous plants such as mountain laurel, pieris and azaleas also fall into that category. In extreme cases, low acidity for plants could impact their overall health and/or the resulting crop.
The green fungus called Trichoderma, is very beneficial to the soil. The blue-green fungus is moderately beneficial. At any rate, moldy coffee is good to use directly in the garden, on your houseplants, or in the compost pile.
The shells also contain other minerals that help plants grow, including potassium, phosphorus, and magnesium. Eggshells are, therefore, an effective and inexpensive fertilizer for outdoor garden soil and houseplants.
Eggshell Benefits
As it happens, eggshells can provide all the calcium carbonate the soil needs, which helps to lower the soil's pH level and make it more alkaline as opposed to acidic. This is incredibly beneficial for plant growth because many plants prefer to grow in soil that has low acidity.