Guest Author - Wendy Lee

Nearly everyone has seen fertilizer or even used it at some point, and every kind of fertilizer has three big numbers on the front, be they 10-20-10, 5-2-7 or 20-10-30. Those three numbers represent what percentage of Nitrogen, Phosphorus, and Potassium is in that particular bag of fertilizer. Nitrogen (N); Phosphorus (P); and Potassium (K); respectively, are the main components of most all commercial fertilizers. They are commonly known as N, P, and K, as these are their symbols on the table of elements.

Each element provides a different attribute to the soil which aids the plant in growth. Also each particular element can come in a multitude of forms.

Nitrogen can be listed on an ingredients list as ammonium nitrate, urea, ammonia, or by the chemical equation of NH3 or NH4+. What it does is promotes new foliage growth, if used appropriately, new growth matures quickly and remains sturdy with dark green leaves. It is best to use a fertilizer with slow release nitrogen so as to get the maximum usage from it as nitrogen tends to leach from soil quickly. Nitrogen is also highly abused and can cause poisoning to your plants, pets and people alike so it is always highly recommended to follow the manufacturers instructions or to even use a half strength fertilizer solution to avoid issues later on. A symptom of over fertilizing or too much nitrogen in the soil is browning of leaves and wilting. Why this happens is the chemical salts suck all the moisture from the soil while being released into the air. The best way to avoid this burn is to A: always follow the manufacturer’s instructions and B: water thoroughly after a fertilizer application.

Phosphorus is represented by the middle number on the manufacturers packaging, it is responsible for root and reproductive development. If your plant isn’t flowering like it used to a lack of phosphorus may be the answer. Also, it may be useful to check out the pH of the soil too much acidity or alkalinity inhibits the release and absorption of phosphorus. Another absorption blocker is too cold of a soil temperature. As with nitrogen, a slow release fertilizer is recommended so that the plant gets the most use out of the fertilizer applied as possible.

Potassium, the third number on fertilizer packaging, may also be listed as potash which is resultant from the antiquated way it was harvested from wood ashes. Commonly associated with bananas and all kinds of healthy things, is used by plants to promote disease and cold resistance as well as helping to protect them from excessively dry conditions by preventing water loss. Fruit development benefits from potassium in the soil as well. Applications of fertilizer known ‘Super Potassium’ are used by farmers growing record sized pumpkins and other gourds.

Besides common chemical and organic fertilizers, the following can also be applied as soil additions: bone meal, dried blood, fish meal, bat guano, earthworm castings and alfalfa meal. In addition, compost or manure may be just enough of nutrient refreshment for any houseplants. A recommendation is when repotting to mix your chosen additives into the soil and top off your repotting with a layer of un-doctored soil.

On a final note ALWAYS follow the directions on the package of your fertilizer and consider using a weaker solution than recommended for the wellbeing of your houseplants as well as yourself, family, pets and the environment.