7) Whey
After making cheese, don’t toss the whey! Whey contains milk solid and nutrients that make it a great fertilizer for your fruits and vegetables. Because whey is slightly acidic, it is especially good for acid-loving plants like blueberries, rhubarb, and some vegetables.
To use whey as a fertilizer, you will want to dilute it with water first. I have seen many recommendations on water to whey ratios, ranging from 1:1 to 2 cups whey to 2 gallons of water. When I use whey, I generally go with a 1:2 ratio – one part whey, two parts water.