Fertilizer Vs Plant Food

In the manual I wrote "How to be Successful with Houseplants From the Plant's Perspective" I wrote an entire section about the use of fertilizers. So many times I have read the term "feed your plants", but is that what you are really doing? I must make the distinction between plant food and fertilizer because the plant actually makes all its own food through photosynthesis. The process involves taking water, carbon dioxide and sunlight to make carbohydrates that actually feed the cells to give them the energy to perform all the daily functions that go on inside a plant. Fertilizers are the nutrients that the plant needs to build those cells. They are the building blocks the plants use to grow. And there lies the difference.

There are two types of packaged fertilizers, chemical and organic, They can be in either granular or liquid form.
Chemicals are mixed in labs from different chemical ingredients to make the analysis you see on the packages (IE: 15-30-15). the numbers on the label of chemical fertilizers are usually much higher than on the organic packages. Organic have the word FERTILIZER somewhere on the label, while PLANT FOOD appears on chemical containers. The organics are taken from natural ingredients and mixed together but still retain their natural states. Chemical fertilizers are designed to be instantly ready for a plant to take up as soon as it is mixed with water. Organic fertilizers are slow-releasing and take time before they are available to the plant. These are safer to use because they will not burn roots if given as directed.

I make the distinction because plants do not need to be given those packaged "plant foods" as often as the manufactures would like you to believe. In fact, giving the plant those chemicals at the wrong time can be very harmful to the plant and even cause plant death. These chemicals found in the "plant foods" are designed to break down quickly as soon as they are mixed with water, but if the plant is not in an active growing mode or is in shock, they will sit in the soil and burn delicate feeding roots. Because organics take time to break down, they will not burn roots unless given in extremely high concentrations.

So what is the real difference as a plant sees it? The nutrients found in fertilizers are the nutrients that the plant takes from the soil. They consist of nitrogen, the first number on the label, phosphorus, the middle number, and potassium, the last number and the trace elements necessary for cell development. We also need trace elements to sustain a healthy body. The carbohydrates the plant makes from light, water and carbon dioxide, are sugars and starches that give the plant energy. This is, of course, a very simplified version as to the metabolism of a plant, but it will give you an idea as to how the plant uses the environment to sustain itself.

Plants actually make all their own food; carbohydrates through photosynthesis, and the minerals it needs to build with by recycling all the parts it looses as the plant grows. All that fall from the plant are broken down into the basic nutrients again in order to provide those building blocks for future growth. After all, no one goes out and feed the forests, and they have been growing longer than we have been on the planet. This is ideal in the outdoors but it is not usually allowed for our houseplant to recycle what falls into the soil. And there is a very good reason for this. That material is broken down by insects, bacteria and fungus, which are not good for a potted plant. These insects and fungus can harm a plant growing inside and can cause diseases that will kill the it. So we need to replace the nutrients the plants use by watering in fertilizers on occasion.

The proper times to use fertilizers depends entirely upon the plants. As I stated, if a plant is in shock, it will be busy repairing that which caused the shock, such as repairing root systems that were disturbed when transplanted, and those roots will not take up any nutrients until they are healed. You can tell when a plant is out of shock when you see new growth. The plant then is in its growing mode and will make use of the nutrients in the soil. In the Northern Hemisphere, the active growing period is Spring through Fall, and as the days become shorter, the amount of growth slows to match the decrease in light. Even though houseplants have a fairly consistent environment, the growth rate slows the same as any plants outside. Even in the subtropical areas, such as Florida and California, this rate slows as the days become shorter. The shorter days are a resting time for most plants. It is only in the topic zones around the equator where the day length never changes and the growth rate stays the same all year.

As we see more new growth, we can add fertilizers in very small amounts as often as every time we water, to once a month at double the strength. I usually use an organic fertilizer every time I water my houseplants during the spring through fall. This forces the most growth in the shortest amount of time. I use a very weak solution and water two to three times a week, depending upon each plant. I never fertilizer during the months of November thought February. This is the dead of winter, and the plants do not need the nutrients during this time. If you you have given fertilizers to your plants all summer, there is enough nutrients in the soil to maintain the plants until the new growth season begins.

In the next article, I will explain how plants use these nutrients to grow its different parts, and how to use fertilizers to direct the growth of your plants, inside and out.