All About Fertilizer – Why, When & How

We know that fertilizer is one way to get and maintain a healthy, green lawn, but there is a little bit of science involved when dealing with which fertilizer is best for your lawn, how to apply it and the best time of year at which to fertilize.

Why Does Fertilizer Help My Lawn?
Lawns need three elements to grow healthy and strong – Nitrogen (N), Phosphorus (P) and Potassium (K), which are found in the soil of your yard. Unfortunately, through various reasons, these nutrients disappear from your soil, leaving brown or dead grass, patchy spots. Nitrogen gives grass its deep green colour and aids in lawn density by fully developing the grass blades. Phosphorus helps the root system to grow thick and branch out, and potassium gives grass its strength, enabling it to withstand high traffic, harsh winters and dry summers.
Fertilizer helps to restore the nutrients to your soil. A good general fertilizer will be listed as 20-5-10 on the bag, which means it is 20% nitrogen, 5% phosphorus & potassium. The numbers on a bag of fertilizer will always be in the N-P-K order. 

Inorganic fertilizer is most common in garden stores. It is made up of chemicals to give a quick release of nutrients to the grass. Water needs to be added so the nutrients will be absorbed into the soil before burning the grass. There is a greater chance for environmental pollution with fertilizer run-off, but it is less expensive than organic fertilizer.

Organic fertilizer is often made of animal manure and has a slow release of nutrients because it has low water solubility. However, it has a low risk of leaf burn and has less impact on the environment.

Best Time of Year for Fertilizer Application
While most lawns will need multiple applications of fertilizer, especially nitrogen since it dissipates the most quickly, it should be applied in late fall, while the grass is still green, but it’s gone dormant. The quick-release of an inorganic fertilizer promotes thick root growth in the fall and spring and will give you an early spring green-up.

Applying Fertilizer & Irrigation
Regardless of what type of spreader you use, even application is key. With a drop-spreader it’s recommended that you create a header row at the top and bottom of the lawn, then go back and forth, with a slight overlap of each row. The header row gives you a spot to turn around, just remember to shut the spreader off, otherwise you will over-fertilize.

Watering after fertilization is imperative and having an in-ground irrigation system can help with consistent water distribution. The water dissolves the fertilizer into the soil before it has a chance to sit on and burn the grass blades, so watering should be done less than 24 hours after fertilizing. A sprinkler system will cut down on how long you will have to water since your whole yard will be done at once.