The words plant food and fertilizer are synonymous. The only difference is that plant food is in concentrated form. Your houseplants, lawn, landscape and garden need to have some kind of food for energy to live and grow.

They get food from the air (CO2) and from minerals in the soil. Their foliage takes in the CO2, and the roots absorb the water and minerals. We cannot give the plant extra CO2, but extra minerals can be added to the soil of your houseplants.

Even if you have very rich soil, eventually the plant will use all of the nutrients and you will have to add fertilizer. In the wild, every year the soil gets naturally fertilized with decaying vegetable and organic matter, shifting topsoil, etc. You potting soil cannot get these things naturally, so you will have to feed the plants yourself.

Fertilizers or plant foods put the nutrients back into the soil that have been used up. Nitrogen, phosphoric acid, and potassium are the three main nutrients that are needed for feeding you plants. These minerals are found in manure and in commercial plant foods and fertilizers.

Organic Fertilizers and Manure

Manure has been used for thousands of years to fertilize crops for farmers. The negative aspects of using fertilizer are it's weight, smell, and it is difficult to store and not one I would use as my primary fertilizer for house plants. Also, for fertilizing your houseplants, you need mix large quantities of it into the soil by hand to make it effective.

Instead you can use liquid manure. This is basically cow manure mixed with water. The water absorbs the nutrients from the manure, and you can then dilute the resulting solution with more water and feed your plants with it. Space is still a problem for this. You can't store the manure in your home. You will need a barn or cellar to make this mixture. The easiest way to feed your plants is simply to buy pre-made plant food from the store.