House plants need the sun or artificial grow lights to provide the energy needed for photosynthesis, but for them to grow to their full potential, you will need to feed them. Like any other living organism, plants need additional nutrients to help them become healthy. You want your plants to develop proper root systems and leaves, strong stems and vibrant flowers. There are a few elements typically found in fertilizers that will act as the food to help your houseplants be all they can be.
Phosphorus - Phosphorus is another key nutrient in the healthy life of a houseplant. Plants need phosphorus, which is commonly found in fertilizers, to produce strong roots and to promote healthy flower blooms. Although there is phosphorus naturally occurring in the soil around your plants, it is primarily insoluble and is usually connected to individual soil particles. This cuts down on the amount of the nutrient the plant can absorb. Adding a plant food containing phosphorus to your houseplants will help ensure your plants get enough. Phosphorus helps your plants absorb carbon dioxide, therefore helping with photosynthesis and fruit production.
Potassium - Potassium is a plant nutrient found in fertilizers that helps the plant metabolize other nutrients into energy. Potassium helps control water absorption into plant pores and regulates the functions of plant growth. Addition of potassium to your plant's diet is also important in helping to stave off diseases and make stems strong and healthy. If your plants do not get enough potassium, you are likely to see signs of deficiency in the form of weak stems and leaves with browning edges, and the plants may be more susceptible to pest infestation and disease.
Water - Water is perhaps the most important part of your houseplant's required care. Since these plants are indoors, they do not receive the benefit of occasional rain. When the plants do not have moisture to feed on, they will dehydrate and eventually die. Houseplants should be watered regularly to prevent the bottom two-thirds of the soil they are planted in from drying out. Add enough water so that the excess begins to run out the bottom of the receptacle the plant lives in. This washes away excess salts and ensures that the bottom area of the soil around the roots has been moisturized.