Indoor plants provide beauty and support environmental health. They require good care in return. "Light, water, temperature, humidity, ventilation, fertilization and soil are chief factors affecting plant growth, and any one of these factors in incorrect proportions will prevent proper plant growth indoors," according to the Texas A&M University website information on growing indoor plants. Good fertilizer is one of the most important plant needs.
All plants use light as their energy source in the photosynthesis process, which creates plant growth food and releases oxygen into the atmosphere. The photosynthesis process also helps clean household air of the chemical pollutants that are a byproduct of furniture, cleaning products and housing materials. Intensity, duration and quality of light are the determining factors for plant growth.
The roots of indoor plants are most often in the bottom two-thirds of the pot. The plant requires more water when this area is dried out. The type of potting medium influences the length of time it takes a potted plant to dry out. The test to determine if a plant needs water is to put a finger 2 inches into the soil. If it is dry, the plant needs water. For small potted plants, the test depth is 1 inch.
Good fertilizer contains all the necessary nutrients. Plants need 17 essential nutrients to thrive, according to Utah State University horticulturalist Jerry Goodspeed. "They are all important and necessary for growth and survival." Carbon, hydrogen and oxygen are supplied by water and air, but the remaining 14 must be available in the soil. Nitrogen, phosphorus and potassium are needed in the largest amounts, and they are referred to as the macronutrients. Micronutrients include boron, manganese, copper, zinc, chlorine, nickel, cobalt and molybdenum. They are also essential for plant growth and health.
Houseplants vary in their rates of need for fertilizer. Fertilizing plants every two weeks from March to September is a general rule. Reduced light and temperature in the wintertime slow plant growth and need for fertilizer. Many fertilizers contain only nitrogen, phosphorus and potassium supplements, which are indicated on the N-P-K label. Natural fertilizers contain a broad spectrum of nutrients.
Natural plant fertilizers contain all the essential minerals and nutrients that houseplants need. There are many brands to choose from, in liquid and granular formulas. Organic fertilizer is made from all natural sources such as earthworm castings, bat and seabird guano, rock phosphate, sulfate of potash magnesia (a mined natural mineral), and kelp. Organic plant fertilizer contains no chemical additives, which can burn delicate plant roots.