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The Mysterious World of Fertilizers


Many gardeners may find choosing the right fertilizer confusing or may just simply overlook the necessity of fertilizers when considering the nutrient needs of their plants.  Luckily, a chemistry course is not required to choose or understand the importance of fertilizers when it comes to the health of our gardens. A quick look at the three main nutrients that make up fertilizers will easily guide you to the one most beneficial for your needs.

While most soils initially carry sufficient amounts of these nutrients, plants can absorb the available nutrients and take them with them to the compost pile when the season is over.  Over watering may also cause these nutrients to run off when the soil is too saturated. While the addition of compost to garden beds does provide some nutrients and enhance structure to the soil, this alone may not provide the sufficient levels of nutrients required.  As we can benefit from the addition of vitamins and supplements to our diet, so too can our plants!  Keep in mind as well, certain plants may have specific needs that these amendments cannot address.

The three main numbers (i.e. 20-10-20) listed on fertilizers respectively indicate the percentage of nitrogen, phosphorus, and potassium available in that particular fertilizer mix.  The higher the number, the greater the amount of the nutrient available.

Nitrogen. The first number listed always represents the percentage of nitrogen in the fertilizer.  Nitrogen promotes vegetative growth thereby giving you a lush green plant.  A fertilizer with a higher nitrogen content is ideal for lawns and for plants that are prized more for their vegetation than for fruits and flowering.

Phosphorus. The second number refers to the percentage of phosphorus in the fertilizer.  Phosphorus promotes root growth and aids the plant in flowering and fruiting.  Adding a fertilizer with a higher phosphorus content is beneficial to plants being newly added to your garden, as this will encourage the root growth necessary to help the plant become established.  Be aware that bare-root plants have a more reduced root system in comparison to potted plants, so using a fertilizer with a very high phosphorus percentage may be necessary.

Adding phosphorus can also be accomplished by including some bone meal in the soil around the root area when planting, as bone meal is an organic source of phosphorus.   This may appeal to gardeners concerned about using chemical fertilizers that can accumulate and run off into our waterways.  Rest assured that there is a wide variety of organic fertilizers that are available to the consumer. We at Rockcliffe Landscaping offer personalized maintenance packages that include organic fertilizers.   

Potassium.  Potassium, also known as potash, is indicated by the third number in the fertilizer mix.  Potassium is essential for the plant to perform its life processes and is therefore necessary for the overall general health of the plant.  It helps to aid in disease resistance and encourages stronger growth by aiding in cell division.  You can see why providing your plant with a source of potassium will result in an overall healthier and stronger plant.

When choosing a fertilizer, consider the need of your particular plant and then pick your fertilizer accordingly.  Keep in mind that some plants can have specific needs.  For instance, evergreens and broadleaf evergreens such as Rhododendrons and Azaleas prefer an acidic fertilizer.  Vegetables will benefit more from a fertilizer higher in phosphorus to encourage flowering and fruiting.  Knowing what you would like to accomplish with your particular plants will help you in choosing the right fertilizer.  If you are still unsure, feel free to contact us at Rockcliffe Landscaping.  As well, general all purpose fertilizers such as a 20-20-20 are usually available with the wide range of fertilizers stocked on the shelves.

Fertilizers also come available in different formats.  Fertilizers that come in a granular form tend to be slowly released over time and may only need to be applied once a year.  A water solulable fertilizer is one that you mix with water and provides more readily available nutrients.  This kind of fertilizer may need to be applied monthly from spring to early August depending on directions.

Whether you are planting a new garden or simply would like to enjoy the lush greenery and beautiful blooms of your existing garden, don’t forget to make sure that you include fertilizing regularly in your maintenance schedule to provide your plants the well needed nutrients they require to stay healthy and perform at the highest level.


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