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Sunday, December 24, 2023

Coffee Grounds and Wood Ash for Soil Fertility

Coffee grounds collected from coffee-shops.
Since we began weening ourselves off the use of animal manures as a source of soil fertility, we have turned increasingly to leaves, grass-clippings, wood-ash and coffee grounds as a replacement. Here is a summary of our "Deep Mulch Method" in which we cover the topic of leaves and grass and other organic materials in our gardens.

Regarding coffee:

Coffee grounds provide generous amounts of phosphorus, potassium, magnesium, and copper. They also release nitrogen into the soil as they degrade. When we have it, we spread it about 1/4" thick on beds before we plant. We also layer it into our compost piles. Here's an informative article about using coffee grounds in the garden: The Ground to Ground Primer – Coffee Grounds for the Garden

For some reason, worms love coffee grounds! By sprinkling grounds in your garden beds, you will attract worms to come into your soil and, since coffee grounds also contain many nutrients on their own, we also recommend adding them to your greenhouse paths and compost bins. They will attract worms and speed up the process of decomposition.
We sift both our coffee grounds and wood-ashes. Here are students from Oregon State Univ. performing "service-learning" by sifting coffee grounds.

...and Wood Ash:

Wood Ashes provide all necessary nutrients for plant growth except nitrogen and sulfur.  We use ashes from our wood-stove (that heats our house). We use only newspaper to start the fires and burn pure wood. We don't burn anything with paint; no ply-wood or other man-made products so the chemicals in them don't get into our food-chain. We sift the ashes to remove any big chunks, and use a heavy-duty magnet to remove any screws or nails.  

Be very careful not to use too much! We put just the lightest dusting in our beds. Do not use wood-ash to make a potting soil. It is caustic to worms and will alkalize your soil so use only a little, and wait 7-10 days before planting seeds or seedlings. Do not use around acid-loving plants (like blueberries, or in potato-beds). Here's an article from SFGate's garden-site: About Enriching Soil With Ash, and here are 12 Uses for Fireplace Ashes That Are Suitable for Your Home (beyond its use in the garden).
Heating with wood has many benefits. Here's a wood-stove in one of our greenhouses we made from a barrel-kit.
Here's Caleb - our youngest coffee-spreader!


  1. Still loving your postings.....always informative and gives me an off-site visit to your warm hearts.....Happy New Year!!

  2. Hi,
    Awesome! Your coffee ground ideas are really awesome! Great work, thanks for sharing your amazing blog.
    Thanks. GardenHubs


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