Some people may be concerned about the acidity of coffee affecting their soil pH balance, but unlike brewed coffee which is acidic, used coffee grounds are nearly neutral in pH (~6.9 pH). It appears that the brewing process strips away the acidity of the coffee grounds. Therefore, adding small quantities of used grounds to your soil should not dramatically change your soil's pH level.
My friend tells me her worms love this stuff so if you have a worm compost bin feed your worms your wet or dry used coffee grounds. I do not have a worm compost bin so I spread the dried used coffee grounds on the soil and work the grounds slightly beneath the surface. The plants will still get the nutrients, and the stowaway worms in my pots can enjoy a snack too.
I seldom drink coffee, but my coffee-loving friends are more than happy to give me their used coffee grounds. I have so much of it now that I give away extra used coffee grounds to other garden enthusiasts who have larger outdoor gardens.
Sources of Used Coffee Grounds:
- Your Home
- Your Office - Place a bag or jar beside the coffee machine and ask your co-workers to dump the used coffee grounds in the container.
- Friends or Neighbors
- Coffee Shops (See Starbucks as an Example)
- Starbucks gives away free used coffee grounds to its customers and local parks as a soil amendment through a program called "Grounds for Your Garden." To find out more about this program, visit Starbuck's website and look under about us > social responsibility > environmental affairs > store initiatives.