Coffee grounds
Sprinkle used coffee grounds around the base of your
plants. Use a fork to stir them into the top layer of soil to add minerals and fluff. Cooled, brewed coffee (no cream, please!) also works. If you like your coffee strong, you might want to dilute it first.
Herbal and black teas
Loose tea or tea bag innards also enhance soil.
Fish tank finds
If you have a fresh water aquarium, save the water when you clean the tank and use it to water your houseplants. If it has been awhile since you last cleaned out the tank, dilute the tank water first. And watch for little fish that accidentally get tossed onto the soil!
Rice rinsings
Save the water used to rinse white, sticky rice before cooking.
Vegetable liquid
After steaming vegetables in unsalted cooking water--everything from spinach and okra, to
potatoes and carrots--pour the cooled liquid around your
plants. Yum, yum.
Fish bones
No, we're not talking whole salmon carcasses here. Just the sharp, pin bones leftover after a meal. Just poke them into the soil and they will break down easily, adding much-needed nutrients to the soil.