Seventeen elements are essential for plant growth. Plants use more nitrogen, phosphorous and potassium than other elements, but growth is limited when a plant lacks any one element. Other essential elements include calcium, magnesium, iron, carbon, hydrogen, oxygen, manganese, copper, boron, zinc, molybdenum, sulfur, chlorine and nickel.
Plants that grow rapidly use these elements more quickly than slow-growing plants. Potting soils generally lack nutrients essential for plant growth, but a regular fertilization program will compensate for this nutrient deficiency. Many strengths and forms of fertilizer are available including granular, liquid and slow- or quick-release. For best results, look for fertilizer made specifically for the particular kinds of houseplants you have. Or, you can use a general all-purpose, complete fertilizer. Fertilization rates and frequency of application vary by manufacturer, as well as season. Always follow label instructions. Using slow-release fertilizers will help plants remain healthy.
Over-fertilization may be a problem and lead to excess salt buildup. In addition, excess salts may build up causing a white crust to appear on the potting soil or the pot. Leach the potting soil in the container several times with clear water to help alleviate this problem.