Beginner Gardening Guide to N-P-K

Beginner gardening Organic organic gardening

Ready to venture into the world of fertilizers? You will need to have an understanding of what the numbers on the front of the fertilizer bag mean.  When you walk into the aisle with fertilizers, you will see three numbers separated by hyphens on the bag.  These numbers represent the three primary macronutrients, Nitrogen, Phosphorus, and Potassium.  What is a macronutrient?  Macronutrients are the essential nutrients necessary in large amounts for growth and development.  Each one of these plays a different but vital role in plant nutrition.  Careful when using fertilizers because applying too much can lead to overfertilization, which will create a whole new set of problems for you to deal with.  If you step in without having any correct knowledge and adequately equipped, you could end up doing more harm than good. 


Nitrogen, the first of the three numbers is the macronutrient responsible for lush green and leafy growth.  An excess can overstimulate the plant.  It is best applied as a slow-release fertilizer before planting.  This way, the plant can take up what it needs.  Careful because nitrogen is highly mobile and can easily be leached from the soil. Nitrogen is vital to composting because they are green material.  When it comes to composting, they kickstart everything.  Organic forms of nitrogen include, but are not limited to, Cottonseed meal, Bat guano, soybean meal, blood meal, and fish and crab meal.


Phosphorus, the second number, is responsible for fruiting, flowering, and strength of tissue wall.  Slow growth, deformed leaves, and a sudden drop of leaves are usually a sign of this problem.  Careful when applying products high in phosphorus because it is extremely slow to breakdown.  An excess can cause nutrient lockout in plants.  Bone meal and alfalfa meal are just a couple of products high in phosphorus.  Excess phosphorus can stop the plant from being able to uptake minerals.  Also, excess phosphorus will kill the mycorrhizal-forming fungi, which is the opposite of what we are trying to accomplish.


Potassium is the third and final number, and it is related to plants health and immunity and root development. This nutrient plays a vital role in fruit/ flower color and flavor. Potassium deficiencies are extremely rare, because if you are adding compost to your garden bed, then there should be adequate potassium in the soil.  You can find potassium in greensand, guano, and kelp meal.

 What you find out after gardening for a while is that maybe you should pay less attention to fertilizers and more time focusing on building health, and diverse soil life.  Focus on ensuring all parts of the soil food web are functioning correctly. A healthy soil food web will, in turn, make sure that your garden is producing at the ultimate level.  Feed the soil, and in turn, the soil will feed the plants.  Fertilizer usually solely focuses on feeding the plant.   While fertilizer is not always the answer if the plant is lacking or underperforming, in the right instances, this addition can help take you over the top. Still, it can also mask issues that need correcting for the long term success of your garden.

Either way, make sure you are paying attention to the health of the soil microbes and the other food web members.  If you are digging a hole in your garden, you should run into many earthworms.  The more you see, the better.  Worms are at the top of the soil food web.  If you see a healthy amount, that means that everything further down the food web is functioning correctly. 

Armed with this knowledge, you are ready to get started going down the fertilizer aisle.


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