What Does Nitrogen Do For Grass? Promote Fast Growth & Green Foliage

By Brian Mounts | Aug 06, 2020
What Does Nitrogen Do For Grass

You’ve probably heard many times over that nitrogen is good for your lawn and that a healthy lawn needs to be fed regular doses of nitrogen throughout the year to stay healthy… but do you know why?

Most bags of fertilizer, both synthetics and organics prominently display their nitrogen contents and in most cases the nitrogen content is the highest percentage nutrient in almost all bags of fertilizer because grass can’t grow without it.

Nitrogen is the single most important nutrient to add to a lawn. Nitrogen allows grass to grow new green foliage above the soil level which is then used by the plant to photosynthesize, generating energy for sustained root growth and disease prevention. Nitrogen fertilizers can be fast release or slow release, synthetic or organic, and in all cases too much nitrogen applied all at once can kill the grass.

Although it’s widely known that nitrogen is good for your grass and that it can help the grass grow faster there’s plenty of confusion out there as to how exactly how nitrogen actually is used by your turf. It can also be a challenge to understand how much nitrogen you need to add to your lawn throughout a growing season and which fertilizer will works best for you and your lawn.

In this article I will shed some light on all of these grey areas and then some.

For instance, do you know how to spot when your grass is getting too little (or too much) nitrogen? Most people only vaguely know that their lawn needs some form of nitrogen, without knowing exactly how much or at what intervals. Once you start looking at it all in math terms it gets a lot easier.

This article should help clear those issues up. Keep reading for a little info on what nitrogen does and how it works, as well as how to make sure your lawn is getting enough on a through fertilizer choice and the frequency with which you administer it.

How Does Nitrogen Work & How Does Grass Use Nitrogen

Nitrogen is an essential nutrient for all plants, not just grasses. The nutrient is responsible not only for the beautiful green color that you see in plant stems and leaves but also for growth itself. It’s an essential element of chlorophyll, the green pigment plants use to produce energy and feed themselves. Without nitrogen, plants can’t produce enough chlorophyll, which means they won’t grow tall and strong. They’ll be weak and brittle, have undersized fruit/seeds, a disproportionate amount of root to stem, or have a color that looks off.

In a lawn this means that the grass blades will be shorter, narrow, dull in color, and susceptible to disease, drought, and heat stress.

This is the main reason why you read descriptive words like “nitrogen-rich fertilizer” being used a lot in the lawn and garden isle — nitrogen is necessary for growth and good color in your lawn. Not having enough of it will lead to a sad-looking lawn.

Less obviously nitrogen is important to a plant’s metabolic processes. Not having enough of it available will inhibit the plant’s chances to grow and to recover from diseases and/or injury.

You can think of nitrogen for plants the same way you think of vitamins in humans.

For example, magnesium is a vital electrolyte our body needs for the most basic metabolic functions. It’s responsibly for building bones and maintaining a healthy skeletal system, but it’s also a necessary human nutrient in terms of regulating muscle contractions. Basically, it just does a lot. As such, a magnesium deficiency might lead to a variety of different symptoms: muscle cramps and pains, fatigue, weak bones and more.

Nitrogen is exactly the same.

Grass and other plants take in nitrogen from the soil when it’s in non-gaseous forms like nitrate or ammonium. In some cases some nitrogen can even be absorbed by the plant during rainfall!

Once nitrogen enters the grass system it is then used for a wide variety of basic processes, like making proteins for energy or creating the DNA and RNA cells need to replicate. And because nitrogen is an essential component of chlorophyll, plants literally need it to feed themselves.

The good news is, nitrogen isn’t hard to find. It’s abundant in both the earth’s atmosphere and the soil surrounding your grass. In fact, there’s about four times as much nitrogen in the air you breathe everyday than there is oxygen.

So why do you need nitrogen fertilizers, if nitrogen is so abundant in the atmosphere?

You need to add nitrogen directly to the soil because plants can’t actually absorb most of the nitrogen found in the atmosphere, which is in gaseous form. Some possibly but not enough.

Nitrogen needs to go through a process called “fixation” and be converted into a form that plants can actually use and that’s where fertilizers come into play.

Grasses and other forms of plants use their roots to absorb nitrogen and other nutrients in from the soil, which means if your soil is low in available nitrogen then you have to add it. Fertilizers allow you to add more nitrogen to the soil for the plant to use and you get to choose whether or not that nitrogen added is readily available or slowly released for sustained feeding. Your chosen fertilization practices give you control over the nutrition your grass needs, which in turn helps the grass to grow.

If you want a green, lush, disease-free lawn, then using a nitrogen fertilizer isn’t just an optional addition to watering your plants; it’s actually necessary. No matter how much sun or water your plants get, without using a fertilizer there may just not be enough available nitrogen for them to grow healthily.

The trick now is to decide which type of nitrogen based fertilizers to use, when to apply them, and in what quantities. Let’s go into those topics next.

Nitrogen Deficiencies Can Be Identified By Color

Because nitrogen is essential to the vibrant color you associate with healthy lawns then you should use the color of your lawn as a queue to know when it could use a feeding. When your lawn has an adequate amount of nitrogen, it will look lush and green. The color will also be consistent throughout the area, without any particularly yellow or orange looking patches scattered around.

Most lawns coming out of winter, especially int he cool season grass zones, will see a rapid green-up in the early spring complete with a strong growth. This time of the year few lawns truly need nitrogen, enough has been stored in the dormant grass over winter to thrive during this part of the year.

Nitrogen Helps Grass Grow Faster

As previously mentioned, nitrogen is also necessary for growth so you should assume lawns that have stunted growth may be lacking some nutrients like nitrogen unless other environmental factors are to blame.

Grasses that are fed with the proper amount of nitrogen will grow fairly quickly complete with wide healthy blades. In the Spring a Fall lawns like this will need to be mowed 1-2 times per week and possibly only once during the hottest parts of summer.

Exactly how quickly your lawn grows (needs to be cut) will depend on a variety of other factors as well, such as climate and elevation, but nitrogen is a crucial component and when the growth slows down it may be a sign that it’s time to feed it.

Nitrogen Helps Lawns Thicken Up

Finally, nitrogen is also necessary for your lawn’s appearance of fullness or lushness. Without nitrogen grass can show stunted growth in blade density and/or thickness. Bunch type grasses may not be as dense as they would be otherwise while creeping grasses may not fill surfaces evenly and fully.

With enough nitrogen, the grass will appear tall and thick, and individual blades will look they way they should. Most people find balance by feeding lawns slow-release nitrogen based fertilizers at regular intervals throughout the growing season.

Common application dates for organic fertilizers closely follow the major holidays in the United States. Memorial Day, July Fourth, and Labor Day are common fertilization dates that allow a lawn to stay healthy all season without ever showing the signs of nitrogen deficiency.

See my full grass growing guide here for more helpful tips – no opt-in needed.

What Does Nitrogen Deficiency Look Like?

The fact is grass needs nitrogen — and quite a lot of it. If your lawn isn’t getting enough nitrogen, then you’ll definitely know, as the signs are completely visible to the naked eye.

Nitrogen-deficient grass will have an off color; it’ll look pale yellow-green or orange/brown rather than the usual dark green. Also, because nitrogen is so important for plant growth, your grass will likely be shorter or more stunted than usual; you may find you haven’t had to cut it as frequently as you normally do. If you examine individual blades of grass, they may have an unusual shape and may even curl in on themselves.

Finally, your lawn as a whole may be patchier and less even/lush than is usual.

In fact in some cases moss growth in the lawn may also indicate your nitrogen levels may be imbalanced with the other micro and macro nutrients. Too much nitrogen paired with excessive watering can cause moss.

You can learn more about these other micro and macro nutrients on the following pages:

What Does Phosphorus Do For Grass?
What Does Potassium Do For Grass?
What Does Humic Acid Do For Grass?
What Does Lime Do For Grass?

Is There Such A Thing As Too Much Nitrogen?

Unfortunately, it actually is possible to give your grass more nitrogen than is healthy for it. In many cases it’s easy to make this mistake with fast-release nitrogen sources or for applications in drought and heat stressed lawns. This may also be more of an issue for synthetic nitrogen fertilizers rather than organic varieties.

Over-application of nitrogen can “burn” your lawn, producing spots or streaks of brown, dying grass. This burning of the lawn is also commonly found in lawns that dogs spend considerable time it due to the urea content of their urine. It is basically a concentrated nitrogen source than can burn dead spots into the lawn wherever the dog goes pee.

How To Not Burn Your Lawn With Nitrogen

To avoid burning your lawn don’t apply fertilizers more frequently than necessary and make sure you always water your lawn gently after you apply it. Most fertilizers should be watered in deeply.

Also, even if it doesn’t look like the fertilizer you currently use is having any effect on your grass, don’t rush to try out a new one until the next scheduled fertilization cycle; overlapping fertilizers is another great way to accidentally burn your grass.

If you apply granular fertilizes make sure to calibrate your spreader before you fill it up and start walking because if your drop spreader or broadcast spreader is applying too much then you’ll probably get burn lines in the lawn.

Best practice for spreaders is to apply in a checkerboard pattern applying half of your product in one direction and the other half in the other direction.

If your lawn does end up getting burned by nitrogen, the first step is to water it deeply and monitor the effects. If you notice new grass growing underneath any dead spots, then you can simply continue to water and weed as you regularly would. On the other hand, if you realize that certain dead spots are not recovering on their own quickly then you may have to reseed the area.

How Do I Find The Right Nitrogen-Based Fertilizer For Me?

When choosing a fertilizer for your grass, reading the label (and not just the marketing headline on the front of the bag!) is incredibly important. The N-P-K numbers on each bag of fertilizer show you the percentage of each macro nutrient in the bag.

“N” stands for nitrogen and it is usually the largest number on the bag. If it say 10 then that means 10% of the bag of nitrogen. If the bag weighs 40-lbs then that means 4-lbs of the bag is nitrogen.

For slow release organic fertilizers a good rule of thumb is to put down roughly 3/4 of a pound of nitrogen onto every 1000 square feet of lawn space. You’ll have to measure your lawn and do the match to find out what is right for you. This is a good example to cover here too because it shows that just because a bag of fertilizer has a high nitrogen count doesn’t mean it’s the right one for your lawn.

As a purchaser you should make sure that any fertilizer you opt for has higher nitrogen content than the other essential nutrients that plants needs, like phosphorus or potassium but in some cases you may want a quick release product over a slow-release product.

Bags of fertilizer always have the three percentages listed relatively prominently on the label (N for Nitrogen, P for Phosphorus and K for Potassium). For starter fertilizers used on newly seeded zones or on fresh sod you may want to choose a product with higher phosphorus content to help establish deeper roots. After all, it’s hard to push leaf blade growth from nitrogen when the root zone of the plant isn’t fully developed yet.

Another consideration is how quickly the nitrogen gets released into the soil.

Bags of fertilizer that say “slow release” are pretty self-explanatory; the nitrogen simply gets released more slowly over time into the soil. If you buy slow-release fertilizer, you can expect to need to reapply it once every two months or so rather than once per month, depending on your climate and watering/cutting schedule.

Quick release fertilizers may need to be applied more frequently but in smaller portion sizes.

Finally, the last big thing to consider is whether or not your chosen fertilizer comes in granule or liquid form. Granule fertilizer is likely easier to spread if you’re a homeowner, if you don’t have specialized equipment or if you don’t use fertilizer very often. It’s also usually cheaper than liquid alternatives.

That said, pros may want to take a look at liquid fertilizers, as they can generally be spread more evenly and plants can also more readily absorb them because they’re in liquid form.

Here’s another post on the site dedicated solely to this decision: Granular vs Liquid Lawn Fertilizers

Wrapping Things Up

Nitrogen is totally essential for grass in any form! It’s a necessary nutrient for plant life and that’s especially true for your lawn. Without an adequate amount your grass won’t grow healthily or consistently. Even though our earth’s atmosphere is rich in nitrogen, plants can’t readily absorb it in its gaseous form; they only get it from the soil so make sure to feed your soil.

That’s why it’s so essential to fertilize your lawn with nitrogen-rich fertilizer; if you want the textbook green lawn with a white picket fence, fertilizer is a necessary component to building healthy soil.