Fertilizers and plant food both do the same thing for your houseplants. Plant food is simply a more concentrated way of adding nutrients to the soil than manure or other fertilizers. Feeding your plants is necessary, but there are several ways to accomplish this.
Like other living things, house plants need food in other to grow and survive. Plants get their food from the air, in the form of gasses that enter the plant through the leaves. The most important of these is carbon dioxide. Plants also get their nutrients from the soil, in soluble minerals that are absorbed to the roots along with water. While you cannot change the gas content in the air, you can add nutrients to the soil.
Even if you start with good potting soil, eventually your plants will need plant food to supplement the minerals in the soil. Outdoors, the soil is replenished every year by decaying plants and natural fertilizers that add nutrients to the soil; indoors, your soil is isolated from these events, and it will need to be replenished by you. Use plant foods or fertilizer to increase the nutrient content of the soil, and your plants will thank you by thriving in your home. Many beginning gardeners do not understand the importance of fertilizer, and their plants will not thrive because of this oversight. Fertilizing your plants is very simple and you will be rewarded with beautiful plants.
Fertilizers and plant foods will replace mineral nutrients that the plant has drawn out of the soil. While all types of soil have hundreds of different minerals, your plants mainly need nitrogen, phosphoric acid, and potash. These three ingredients are found in animal manure and commercial plant foods. They are more concentrated in plant foods, because these have been specially formulated to replace these minerals.
Manure, including that of cows, sheep, and chickens, has been used for centuries to help plants grow. However, it can be difficult to use indoors on your house plants. It is bulky, hard to store, and of course has a smell that you probably don't want in your home. It is also difficult to use in small doses on your houseplants, because it is not as concentrated as commercial plant food. If you use manure on your houseplants, you'll need large quantities, which you must work into the soil by hand.
Many home and house plant gardeners use liquid manure as fertilizer instead. Steep a bag of cow manure in water, which will dissolve the mineral nutrients. Then, this strong water solution can be diluted to feed to your plants. However, you'll still need the space to store it, and it can take some time to make this solution. If you don't have space or time, choose a commercially prepared plant food for your houseplants. It is very concentrated, making it easy to store. Plus, it can be used in small quantities, perfect for feeding a small group of indoor plant.
