1. Home
  2. Advice
  3. Gardening A-Z
  4. Fertilizer Basics
  • Fertilizer Basics

    What is a Fertilizer?

    Fertilizer is a substance added to the soil to improve its fertility. Many elements contribute to a soil's fertility. There are three major elements which are needed by plants: Nitrogen (N), Phosphorus (P), and Potassium (K). These elements are needed in large quantities and are not readily available in most soils. There are also thirteen minor elements which can be found in varying degrees in fertilizer: Zinc, Manganese, Boron, Iron, Sulfur, Copper, Magnesium, Molybdenum, and Chlorine. These elements are not less important than major elements; they are simply not needed in such an abundance.

    The right fertilizer analysis in the soil is important for several reasons. First, a healthy plant fights insect and fungus damage much better than an unhealthy one. Second, proper fertilization promotes more consistent plant growth and bloom development. Third, it encourages better root development.

    How Much Fertilizer Do I Need?

    The amount of fertilizer needed depends on the current analysis of your soil. It is advisable to obtain a soil test kit. You can get a soil test kit at your neighborhood Armstrong Garden Center and then send the completed test to your local county extension office to get the results.


    What Do the Numbers on the Fertilizer Mean?

    There are three numbers listed on each bag of fertilizer. These are literal percentages of N-P-K that are in that bag of fertilizer. For instance, if the numbers read 31- 3-10, 31% of the bag is Nitrogen, 3% is Phosphorus, and 10% is Potassium. The numbers will always be printed in the same order: N-P-K. Very often, the numbers do not add up to 100%. If this is the case, other minor elements and fillers can also be included in the bag.


    What Do Each Of the Major Element Do?


    1. Promotes vigorous blade, leaf and stem growth.
    2. Encourages dark green color.
    3. Assists in chlorophyll production.
    4. Improves overall plant health, quality, and density.
    5. Aids in tolerance to heat, cold, and drought stress.



    1. Promotes early plant development.
    2. Hastens plant maturity.
    3. Promotes bloom and root development.



    1. Improves tolerance to drought, disease and heat.
    2. Increases winter hardiness.
    3. Aids in water uptake.
    4. Enhances overall health and vigor.


    What Effect Does Lime have on Fertilizer?

    Just because fertilizer is in the soil doesn't mean that the plant is able to use it. When a soil's pH is too low (below 6.0) or too high (above 7.0), it can severely limit the plant's ability to take in the fertilizer's nutrients. Forty pounds of lime per 1,000 square feet annually is generally recommended.

    See more articles about: Gardening for Beginners, Garden Care