Plants derive most of their nutrition from the soil around them. However, repeat-planting sites, commercial potting soil or soil for potted plants more than a year old often need supplementation. But this does not mean that every houseplant owner or backyard gardener must purchase synthetic fertilizers. There are plenty of household items that make great homemade fertilizer as well as offer interesting ways to reuse waste products.
Coffee and coffee grounds are excellent fertilizers for nitrogen- and acid-loving plants such as azaleas, roses, jade and tomatoes. Dump room-temperature black coffee on the soil surface, similar to your standard watering procedure. The grounds can be mixed into the soil when transplanting or spread out mixed with eggshells for added potassium. They also are a good ingredient to add to homemade compost.
Fish Tank Water
Fish tank water is rich with the wastewater of fresh water fish. According to Marion Owen, co-author of Chicken Soup for the Gardner's soul, water from a freshwater tank works as fertilizer. Fish tank water may have an offensive odor if the tank has not been cleaned in a significant amount of time. If this is the case, dilute with water.
Owen also recommends using the unsalted water left over from boiled or steamed vegetables. The cooking water of spinach, broccoli and other vegetables contains nitrogen, calcium and folate, all important for green plants but are necessarily abundant in the soil.
According to Mother Earth News, a natural living magazine, the residue from empty milk containers is abundant in nitrogen, phosphorus and potassium. Prior to recycling your milk cartons, rinse the container with water and dump over plants.
Household Fertilizer Mix
Many gardeners rely on a mixture of household products such as Epsom salts and ammonia to supplement their plants' diet. Recipe Zaar, an online cooking web site and forum, lists this recipe for making homemade fertilizer: Combine 1 tsp. baking soda, 1 tsp. Epsom salt, 1 tsp. saltpeter, 1/2 tsp. ammonia and 1 gallon of water. This mixture may be applied once every four to six weeks.
Composters and rose gardeners alike can tell you about the many benefits of using eggshells in the garden. Eggshells may be crushed up into a fine powder supplement and added to the soil as a fertilizer. They are rich in potassium and calcium, which will benefit both green plants and plants that bloom.