Use Your Old Coffee Grounds in the Garden. Camellias, hydrangeas, and roses are all nitrogen loving plants so the coffee grounds help. The grounds are also a great deterrent for slugs and snails around hostas and other plants that the pests love.
Dont throw out the water your boil your eggs in. This water contains tons of calcium that your plants will love. Just let the water cool and dump it on your plants. I also save my egg shells, rinse them out real well, smash them up then mix them with dirt
14 Common Plant Diseases: How to Identify & Treat Them