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.
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.
Add grounds to your compost pile, layering one part leaves to one part fresh grass clippings to one part coffee grounds, by volume. Turn once a week. This will be ready in three to six months.
In short, the answer to “Can you put coffee grounds in compost?” is yes. Not only can you add coffee grounds to any composting setup, but you should. Coffee grounds are beneficial for your soil, and they're one of the easiest food wastes to compost.
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.
'Your roses, azaleas, lilies, and hollies because they are acid-loving plants that will thrive best in the acidic characteristic of coffee grounds,' he adds.
There are a select few plants that can benefit from fresh grounds—including acidity-loving Hydrangeas, Rhododendrons, Azaleas, Lily of the Valley, blueberries, carrots, and radishes—but generally, most common houseplants will prefer low to no acidity.
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.
You may find that adding coffee grounds helps: the additional heat helps break down intermediate components created by the composting process more quickly.
Coffee grounds have a relatively high nitrogen content, similar to vegetable scraps, so they are generally categorized like food scraps for compost recipe building. They help generate heat to speed up the decomposition process.
Let's just start out by saying: putting egg shells in your compost is okay; they are a rich source of calcium and other essential nutrients that plants need.
Coffee Grounds as Fertilizer
Add coffee grounds directly to your garden soil in your garden by raking them into the top couple inches of soil or simply sprinkling the grounds on top. In smaller amounts, especially when mixed with dry materials, coffee grounds will give up their nitrogen.
Banana peels are a great ingredient for your compost or worm farm, adding lots of nutrients to the organic recycling process.
When composting, she recommends that gardeners add no more than 20% of their total compost volume in coffee grounds. Levels as high as 30%, she suggests, can be “detrimental.”
Coffee is bad for plants for the same reason most people love drinking it - because of the caffeine. It means coffee is allelopathic - reducing the growth of other nearby plants that compete for minerals or water.
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. By mixing some coffee grounds into the soil below your tomato plants you're introducing these nutrients that the plants need to thrive.
Some materials compost more easily than others. Materials such as wood and leaves are high in lignin, which is difficult to compost, especially when this material is large in size. Other materials, such as grass clippings and shredded paper, compost a lot faster.
Peas and beans are the two most common crops used to replenish the nitrogen content of the soil.
Composting tea bags is an environmentally-friendly practice that all tea drinkers should consider incorporating in their daily routines. Tea is a natural, organic material that's rich in nutrients, and it's easy to add to a compost pile.
You can also put cardboard egg cartons in a compost pile. They break down quickly and will help create rich fertilizer for your garden. You can also compost the egg shells!
Brown Materials
Eggshells (minimal impact): They take a long time to break down, but they provide calcium and are a good addition to compost piles. Hay (15 to 30:1): All types of spoiled hay make an excellent addition to compost piles. Leaves (50 to 80:1): Dead or dry are considered brown materials.
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.
Roses do like coffee grounds, but too much too close can give them a nasty nitrogen burn and can kill your roses. Never sprinkle coffee grounds right next to the plant.