Applying fertilizer in the summer

Applying fertilizer in the summer

There are four questions to ask before applying fertilizer in the summer months.

  • What is the climate of this area?
  • What type of grass the lawn is?
  • What type of fertilizer is being used?
  • What are the expectations of how the lawn should look?



Every area of the country has a different type of climate. In Illinois, we have very hot, humid and dry summers but also have very cold and sometimes snowy winters and temperatures that fluctuate from day to day. This climate takes a toll on the grass and can make it difficult to grow if not the proper type for this area. In Illinois, a cool-season grass is the most common such as fescue.

Grass Type

There are two different types of grasses: cool-season and warm-season. Cool-season grasses such as fescue are able to better withstand changing temperatures as well high drought tolerance and disease tolerance. Other examples of cool-season grasses include bluegrass and rye grass. These grasses are typically a thin or thick blade grass, depending on the variety planted.  Cool-season grasses green-up and grow in the spring and the fall. In the summer and winter they lay dormant. During the summer months, cool-season grasses do not want or need a nitrogen-rich fertilizer. Applying such fertilizer may result in more stress or even burn to your lawn.

Warm-season grasses such as Bermuda and Zoysia grasses green up and thrive during the summer months. Bermuda and zoysia are both creeping grasses, which will spread throughout the lawn, that look almost like small vines. The leaves of Bermuda and zoysia brown out in a fall and will green up late spring or early summer. It is right before or during this “green up” that fertilizer is needed.

Fertilizer Type

There are two types of fertilizer: synthetic and organic. Synthetic fertilizer is a man-made product that gives the lawn a quick boost by releasing nutrients into the soil almost instantly. The ingredients of this fertilizer consist of 3 components; Nitrogen (N) supports the health of stems and leaves; Phosphate (P) promotes a healthy root system; Potassium (K) helps maintain a water balance. A label for synthetic fertilizer will have numbers associated for each nutrient, called the NPK value. Other ingredients may exist in fertilizer as well such as Magnesium, Calcium, and Sulphur. Synthetic Fertilizers are typically slow release or fast release and the two forms are used in combination with each other throughout different seasons each year. Synthetic fertilizer does have benefits and disadvantages. Since synthetic fertilizer is man-made rather than naturally occurring, it can be harmful to children, pets, and the environment. Synthetic fertilizer, however, does allow for that quick “green up” that most people are looking for and makes it a primary choice for those that maintain a lawn care regime. Another reason why it is a top choice, is that man-made products can be produced quickly, allowing for lower pricing than an organic program.

For cool season grasses, synthetic fertilizer will not be applied during the summer months. Synthetic fertilizer that has not been watered into the lawn completely will cause stress to the lawn and often times result in fertilizer burn to the lawn.

Organic fertilizer is a natural source of fertilization. These fertilizers are processed from natural sources such as manure, compost, fish meal and more. Organic fertilizer also follows the NPK rating system. While organic fertilizer is a more natural and a little safer of an approach than synthetic fertilizer, it does miss some benefits that synthetic can offer. Organic fertilizer is considered to be more of a soil conditioner, rather than a grass fertilizer. The course to condition the soil is a long process that may not prompt a quick green up in the spring and fall (for fescue grasses) because it does not give off that “quick boost” that synthetic fertilizer does. While many may not worry about a speedy green up and would like to take advantages of the safer alternative of using organic, the price is typically more expensive than a traditional synthetic program.

No matter the grass type, organic fertilizer can be applied during the summer months, as it will not stress or burn the lawn. This is sometimes considered an option to give the lawn the best of both worlds and allow for the green up most like to see but allowing for soil conditioning each year.


Based on expectations, the right lawn care program can be selected fairly easily. When choosing the right program, there are a couple of things to consider such as green up time or a more corrective approach.

Want a bright green lawn this spring and fall, quickly? Synthetic fertilizer is the option to choose. Some would consider a synthetic approach to be a quick fix for the lawn. It will get it healthy and green fairly quickly. Synthetic fertilizers start at the leaves and stems of the plant and work their way down.

Would you rather have the ‘root’ of the problem tended to and allow the lawn to green up naturally over time? Organic fertilizer would be the right option. Organic fertilizers are more of an over-time fix because they start with the soil. Over time, a conditioned soil will result in healthy and green lawn.

Sum it up

To sum it up, the grass type and the climate you live in are two of the main factors to take into account when considering whether or not to apply fertilizer during the summer months. Regardless of any factors, synthetic fertilizer should never be applied during the summer to a dry lawn as this will promote burning.

It is always a good idea to consult with a lawn care professional and ask any questions you may have. Look around, ask friends or family, and research companies on the Better Business Bureau to find a company that you can trust.

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