Coffee grinds are high in nitrogen and therefore acidic on the pH scale, which is essential for plant growth. You can either sprinkle the coffee grinds directly onto the soil or add them to your compost bin, which is great to help activate the composting process.
Use with caution around alkalineloving plants, though — the last thing they need is a coffee fix. Use them freely around azaleas, rhododendrons, camellias and gardenias, though.
You can also pour cooled percolated coffee around the plants fortnightly or sprinkle left-over coffee around the base of each plant on monthly basis. Do this and your garbage bin may never see another ground again.
Coffee diluted with water, olive oil and a drop of washing liquid is also great as a foliage spray, helping to control a variety of insects while providing some good nutrients to the plants at the same time.
1 tsp coffee grounds
100ml olive oil
900ml water1 organic soap, grated
Shake well and spray as often as required to keep plants green and healthy.