Plant food provides essential nutrients for plant growth. It is manufactured in liquid, pellet, granular and composted forms. The plant food formulas most beneficial to plant growth also feed and nurture the soil. Natural plant foods support and stimulate the biological activity in soil which in turn, feeds plants. Healthy plants grow best in nutrient-rich soil fed by plant food formulas that contain a variety of natural substances.
"Twenty nutrients have been identified which plants require for proper growth and function," according to the Cornell University Extension website. Air and water supply oxygen and hydrogen and the remaining 17 must be supplied by soil. Nitrogen, phosphorus and potassium are needed in the largest amounts. The most beneficial plant food formulas are ones that supply the 17 essential nutrients in the balance needed by particular plants. Roses have different nutritional needs than vegetables and fruit trees.
Many plant food formulas focus on supplying the macronutrients nitrogen, phosphorus and potassium. The remaining 11 nutrients (micronutrients) are needed in trace amounts but they are as necessary as macronutrients. Plant food formulas high in nitrogen stimulate plant growth but do not support healthy soil functioning. High nitrogen content plant food formulas are associated with the nitrogen- overload that causes global pollution, according to the World Resources Institute on excessive use of fertilizer in commercial agriculture.
Calcium, magnesium, sulfur, iron, manganese, zink, copper, boron, molybdenum and chlorine are essential micronutrients found in balanced plant food formulas. Nitrogen needs calcium from soil for its function as a protein synthesizer. Boron aids in the production of sugar and starch in vegetables and fruit. Copper is a catalyst for enzyme and chlorophyll synthesis. Micronutrients are created by the natural biological activity in soil.
Plant food formulas are derived from natural sources such as kelp powder, animal manure, rock powders, fish powder and fish meal, feather meal, bone meal, cottonseed meal, alfalfa meal, blood meal, bat guano and corn gluten meal, according to the Colorado State University Extension website. The fertilizer and plant food industry is not regulated by the USDA National Organic Program but many organic producers used the Organic Materials Review Institute to certify their products.
Plant foods such as liquid fish fertilizer and organic fertilizer pellet formulas are useful in the home garden in spring as the growing season gets started. Backyard compost made from grass clippings, yard clippings, leaves, newspaper and kitchen scraps provides a natural plant food formula of balanced essential nutrients. Backyard compost is made in three to six months in compost bins that help retain the heat necessary for rapid decomposition.