Coffee by-products can be used in the garden and farm as follows:
Sprinkle used grounds around plants before rain or watering, for a slow-release nitrogen.
Add to compost piles to increase nitrogen balance. Coffee filters and tea bags break down rapidly during composting.
Dilute with water for a gentle, fast-acting liquid fertiliser. Use about a half-pound can of wet grounds in a five-gallon bucket of water; let sit outdoors to achieve ambient temperature.
Mix into soil for houseplants or new vegetable beds.
Encircle the base of the plant with a coffee and eggshell barrier to repel pests.
If you are into vermi-posting, feed a little bit to your worms.