Houseplants, or potted plants, sometimes lack essential nutrients due to the nature of being potted. The soil in a pot has a finite amount of nutrients to start with, and the houseplant uses up those nutrients fairly quickly. Any nutrients not used are often flushed unknowingly out of the soil with frequent watering. Unless the lost nutrients are replaced, the houseplant may suffer. Using Knox unflavored gelatin, you can replace the nitrogen plants require for good foliar growth.
Gelatin is a pure protein processed into a powder and then packaged for sale. The gelatin manufactured by Knox is typically used in cooking as a thickening agent for desserts and gravies. When dissolved in water and allowed to chill, the gelatin "sets" liquids which can then be eaten as desserts. As a protein, gelatin is rich in organic nitrogen and much safer in the home than inorganic nitrogen, which is chemically produced. Chemically manufactured nitrogen is easy to overuse on plants and can burn them, causing damage and even plant loss; it is also unsafe for human consumption and must be kept out of the reach of children and pets.
An impressive 80 percent of the earth's atmosphere is made up of nitrogen. It is essential for both plant and animal growth, contributing to tissue development in plants on a cellular level. Without nitrogen, plants' older leaves lose their vibrant green coloring, becoming sickly yellow.
Feed plants with Knox gelatin once a month to keep their nitrogen levels up. Dissolve a pouch of gelatin in 1/4 cup of cool to room-temperature tap water in a 1-quart pitcher, allowing a minute or two for the gelatin to soften. Add in an additional 1 cup of cold water and stir until the gelatin is fully dissolved. Top off the pitcher with cold water, stirring as you go. You may also use flavored gelatin desserts as long as they contain sugar and no artificial sweeteners. It is recommended that these be sprinkled onto the soil using a salt shaker.
It is not recommended that you use Knox or any other type of gelatin on flowering plants, such as African violets. Nitrogen encourages green growth but discourages blooming. Overusing it on florals may minimize their bloom time.