Lawn Maintenance Basics: Fertilizing

The simplest way to describe fertilizer is as food. Just like we reach for veggies and fruits when we feel we are lacking energy, grass needs nutrients to look at its best. However, just like too much food can be bad for you, too much fertilizer can harm the grass as well.

Fertilizing can be a daunting task without taking the time to study the subject. Between determining what fertilizer is best, how much to apply, when to apply it, calibrating your tools, and making sure that you don’t harm the environment, it is enough to make your head spin. There is no way to summarize everything you need to know about fertilizing in this post, but we will give you enough knowledge to point you in the right direction of things you certainly need to research further.

How to Know when Grass Needs Fertilizing

The best way to determine what nutrients your lawn needs is with a soil test, your UGA Cooperative Extension office can help you with that or you can call us, and we can take your samples and process them for you.

Besides doing a soil test there are other symptoms to look for. Your grass will show you when it needs some food. The most evident sign of your lawn needing fertilizer will be a change in color. A deficiency of any of the macronutrients (nitrogen, phosporus, potassium, calcium, magnesium, and sulfur) needed for the grass to maintain its vigor will result in a change in color or some sort of distortion of the leaves. You will need to know how to look at the grass blades to determine which macronutrient is deficient.

For example, nitrogen deficiency will look like general yellowing of the leaves along with patchy or slow growth, but with phosporus deficiency the grass looks dark green in color that progresses to a purplish to reddish purple color.  It takes experience to recognize macronutrient deficiencies therefore we highly recommend conducting a soil test. Easy peasy!

The main reason to fertilize is to maintain a healthy lawn so you don’t have to deal with diseases, pests, weeds, and water runoff. In addition, a healthy lawn will have strong roots and it will also better tolerate stresses such as heat, drought, and cold snaps.

What is a Fertilizer

Fertilizers contain three main macronutrients needed by your lawn to grow: Nitrogen (N), Phosporus (P), and Potassium (K). Most fertilizers will have a 3 number ratio on the label. These numbers are the percentages of nitrogen (N), phosphorus (P), and potassium (K), or N-P-K ratio of the fertilizer.

It is important to choose a fertilizer with a high level of nitrogen as nitrogen promotes healthy leaf growth by encouraging the production of chlorophyll, which is a chemical vital to photosynthesis. Chlorophyll means green lawn. Although your lawn doesn’t need as much phosporus and potassium as it needs nitrogen, it is important to refer to your soil test to select the best N-P-K ratio for your needs.

Another factor to consider when selecting a fertilizer is the season in which you are applying the fertilizer. In general, use a higher nitrogen fertilizer in the spring and for the fall, it is best to use a potassium-rich fertilizer to prepare the lawn before winter arrives.

Types of Fertilizers

Fertilizers can be categorized as organic or synthetic depending on what they are made from. They both have advantages and disadvantages to include cost. Choosing one is going to depend on the requirements of your lawn along with how much you are willing to invest in it.

Another way of categorizing a fertilizer lies on its formula, soluble, granular, or slow release. Again, each of them has their own benefits. Which to use will vary from person to person as you will need to consider, the immediate need of the lawn, the time you have to dedicate to applying the fertilizer along with the method of applying it, and the cost among other very individual needs. For example, if you know you are going to be out on vacation and won’t be available to apply another round of fertilizer, slow release would probably be the best way to go. Whichever you decide to use, be careful with fertilizers with higher concentrations of nitrogen as it is easier to burn the lawn with those.

How Much Fertilizer to Apply

Refer to your soil test. In general, all lawns need fertilizer during active growth. Lawns should be fertilized at least 4 times a year with 1 lb. of nitrogen per 1,000 sq. ft. at each application.

Both cool-season and warm-season grasses require 4 to 6 pounds of actual nitrogen per year. This amount is usually divided into 4 applications of 0.5 to 1 pound of actual nitrogen per 1,000 sq. ft. per application. Do not apply more than 1 pound of nitrogen per 1,000 sq. ft. in a single application or you take the chances of damaging your lawn. Application rates will vary depending upon the formulation and type of fertilizer selected and on the turf species.

We cannot stress enough how important it is to read the label to determine the amount of each nutrient (N-P-K). These numbers are important because it determines the percent of nitrogen that specific fertilizer contains and therefore the amount of actual product you will need. If you use a high percentage nitrogen fertilizer, then you will need less actual fertilizer product to supply that one pound compared to a fertilizer with lower percent nitrogen. A bit of math is going to be required to calculate the amount needed and don’t forget to measure the square footage of your lawn before you head to the store.

Do not over apply, besides damaging your lawn, that product ends in our water sources. Nobody wants to pollute our environment.

When to Fertilize

Preferably after you have aerated your lawn so the fertilizer will get down to the grass roots.

The optimum time to fertilize is going to depend on your type of grass. For cool season grasses it is best to fertilize prior to the seasons when the grass has vigorous growth. Fall and spring are the best seasons to fertilize cool season grasses. Do not fertilize cool season grasses in the summer, the heat of the summer can damage the turf.

Warm season grasses should be fertilized from spring through the summer. The first application should be made in the spring when the grass is 50% green. Unlike cool season grasses, do not fertilize late in the fall. Applying fertilizer in the fall encourages the grass to keep growing and you want it to go dormant, so the next frost won’t damage it.

How to Apply Fertilizer

How you apply your fertilizer is going to depend on the type of fertilizer selected. It doesn’t matter which tool you use to apply it, a hose, or a type of spreader, you will still need to calibrate the tool to apply the product in a uniform way. Make sure your application rate is consistent to avoid burnt or super green patches.

If you selected a granular type of fertilizer and have never used a spreader, it is best to practice on the street with a sheet of plastic to determine the swath width. Use the right-angle method or the half-width method of application to ensure uniform distribution of the product.

Tip: Remove leaves from your lawn prior to applying your fertilizer. You don’t want all that precious product to go to waste.

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