Why are used coffee grounds a good fertilizer for outdoor plants?

Why are used coffee grounds a good fertilizer for outdoor plants?

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  1. You’ve gotten several vague answers. I’ll give you a more scientific answer and try to keep the science to a low level. The answer is that coffee beans, like all beans, contain some protein. Protein contains nitrogen but not in a form that plants can use. Other materials which contain protein are corn, wheat, soybean, and alfalfa. Coffee and corn have a relatively small amount of protein in them compared to the others I’ve listed, but still enough to be a viable fertilizer when used at a rate of 20 pounds (dry) per 1,000 square feet 3x per year or 1 heaping handful (wet or dry) under shrubs every month. I’ve tried drying 20 pounds of wet coffee grounds, and found it to be impractical. Even if I succeeded, the coffee absorbed humidity from the air faster than I could dry it out. With that in mind, coffee is not useful for a lawn, but works very well for individual plants like in a vegetable garden or roses, for example.
    Protein from the coffee is decomposed by microbes living in the soil. There are probably 30,000 different species of microbes in any garden. Those living at the surface decompose the coffee grounds and other microbes decompose the byproducts and dead carcasses of the surface dwellers, and so on. Eventually (usually 3 weeks) the original coffee protein will have been turned into a nitrogen type of plant food. Mother Nature has been perfecting this process for billions of years.

  2. You’ve received several good answers. I can add a little on the specifics.
    Coffee grounds do contain small amounts of three essential nutrients: nitrogen (N), phosphorus (P) and potassium (K). Those are the three numbers that you see on most commercial fertilizers. The grounds also have magnesium, calcium, iron and chromium, all micro-nutrients. Depending on your soil qualities, coffee grounds can make a noticeable difference in growth and vigor.
    You won’t get a big growth boost from the nitrogen, but if you spread your grounds in the garden on a daily basis, it adds up. Plus, you are adding organic matter that will break down, which is always helpful.
    Coffee grounds are a bit acidic, so they are not well-suited for spreading around plants that prefer alkaline soils.

  3. Coffee grounds are plant matter with nothing else in them, not counting a little water. Their texture is food for keeping soils friable, instead of compacted, which allows the plants roots to grow stronger and more easily. Plus, they’re acidic, which many plants like. I add them to the hole when I plant blueberries which makes them grow like mad. Otherwise, I add them to my compost pile.

  4. Simply sprinkle the coffee grounds into the soil and it will make great fertilizer because they contain several key nutrients required for plant growth. The coffee grounds can also help attract worms and decrease the concentrations of heavy metal in the soil.Coffee grounds are great fertilizer for hydrangeeas, rhododendros, azaleas, lily of the valley , blueberries, carrots and radishes.

  5. There are a waste that is small particulate which has been roasted and then steamed in the percolator, so they decompose rapidly.
    Pretty much any kitchen waste that is small particulate will make good soil when it decomposes, because it contains dense nutrient value. Banana skin is excellent as it contains potassium, and egg shells are also very good because they contain calcium.
    The coffee grounds are just readily available, I used to hear caffeine gives the plant a kick. But I think that’s just a funny myth to be honest.
    To make the best use of kitchen waste use a worm box and feed those worms your scraps, and old newspapers or paper will also work. The worms will digest it and make worm castings. This is far superior to any straight up grounds.
    Grinding up meat bones like chicken bone, fish bones etc if you have the facility to do so will also provide excellent feed. Clam and Oyster shells are also extremely good for soil creation, they are also good poultry feed. Essentially any kitchen / restaurants waste is a business in itself if you turn that waste to soil or other products. So many cities waste processing take this and make soils for the public from the organic waste to make it useful again.
    If you take a container and fill it half with molasses then take all your waste like fruit peels, vegetable off cuts etc (avoid straight up meat it will stink, but bones is ok) and put that in the container. Cover it for around 2–3 weeks and leave at room temp, in a dry place. You will get a very rich liquid plant food called bokashi. Dilute to one part of this molasses mix to 6 parts water and feed to your plants they will bloom very well and it’s great for producing vegetables with. You can also use bokashi as a ground amendment to start a new patch. Just pour it into the bed and mix with dung and wood chippings and mulch. Then water the bed in and you can sow a few days after. You can also add an innoculant such as mamothP or any EM.

  6. Using coffee grounds will add organic material to the soil. They will help improve drainage, aid in retaining water, and act to help aeratate your soil. They also help microorganisms which are beneficial to growth. They further help attract earthworms which are also, in general, quite beneficial.

  7. Used coffee grounds are not a particularly good fertilizer, because they are so acidic.
    However, acid-loving plant can get a lot of nutrients out of coffee grounds. We collect them from coffee houses and put them on our blueberries.

    Victor Allen’s

  8. Cofee grounds contains nitrogen phosphorus and potassium (NPk) this nutrients are very important to outdoor plants potassium and phosphorus helps in blooming nitrogen helps in keeping plant green and healthy so coffee grounds are used as good fertilizers for outdoor plants

  9. Coffee grounds are rich in nutrients and slightly acidic,
    Especially good to use spent coffee grounds for plants that prefer a slightly acid soil – blueberries black berries (most woodland berries)
    rose bushes

  10. All the organic matter is made of some or the other nutrients, when waste coffee grounds are added to soil they act as a fertilizer and improve the Texture of the soil, thus improving water retention and increasing overall productivity of the soil.
    The texture of the soil is as important as the nutrient content of it!🌴🌱🌱

  11. The main benefit of using coffee grounds as a fertilizer is that it adds organic material to the soil, which improves drainage, water retention and aeration in the soil.
    The used coffee grounds will also help micro-organisms beneficial to plant growth thrive as well as attracting earthworms.
    Fresh coffee grounds are quite acidic. Used coffee grounds are pH neutral. If you rinse your used coffee grounds, they will have a near neutral pH of 6.5 and will not affect the acid levels of the soil.


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