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When Should You Fertilize Your Lawn?

I had a landlord once that was a lawn fanatic. I had to keep that sucker lush, green, and growing from early spring through frost. Ordinarily that probably wouldn’t be a problem, except it was huge, it was in a desert, and there wasn’t any in-ground sprinkler systems. Because of this the soils were extremely poor as well, and I found myself constantly questioning when to apply lawn fertilizer.

Coincidentally I used to cringe at fertilizer prices for the size I had to cover, and dreaded spreading it since I also had to manage to keep both dogs and children away for the set time period. However, since owning my own property (with a healthy size, but much more manageable lawn), I’ve learned there are a few techniques you can apply to work smarter, not harder, to keep your grass lush and growing green by knowing when to fertilize a lawn.

If you take pride in your lawn, then you too know that there is certain amount of maintenance involved with lawn care, but you don’t have to break your back doing it. Read on to find the answer to how often should you fertilize your lawn.

Why Fertilize a Lawn?
fertilize-a-lawn

Fertilizer adds the essential nutrients needed to keep your grass growing. Growing grass uses up the ‘foods’ found in the soil, and if they are not replaced somehow, that food eventually runs out and your grass will begin to fade and stop growing as well.

Ideally (and in the perfect gardening world), whether you have laid sod, grass seed, or have inherited a lawn with your house- the topsoil the grass roots are growing into are at least four or more inches deep and are a healthy mix of decayed organic material and sand for good drainage. You also have the perfect amount of rain to prevent nutrient run-off, and your grass grows a uniform amount each month before needing a trim. If this is the case, then you most likely have everything you need to feed your lawn without adding fertilizer by leaving behind some grass clippings every so often during cutting.

What Type of Grass Do I Have?
magnifying-glass

Before determining when to fertilize, you need to determine what kinds of grasses you have to optimize the adding of new nutrients. Cool season and warm season grasses grow differently, take water differently, and consequently take up nutrients differently. Determine your grasses and growing seasons, and then pick your fertilizer based on needs.

When to Fertilize Cool Season Grasses

Cool season grasses, as expected, grow in cooler climates. They stay mostly green year round where they have cold winters, and cool (but not hot) summers. Growing seasons that average between 60-75 degrees that include cold winter months are ideal. Many lawn owners ask when to apply winter lawn fertilizer, but for winter lawns you will want to fertilize in fall.

These grasses include:

  • Kentucky Bluegrass
  • Fine or Tall Fescue
  • Bentgrass
  • Perennial and Annual Ryegrasses
Fertilizing cool season grasses should occur three times a year, twice in the fall, and once in the spring. Fall feeding is the most important time to fertilize, and should occur about six weeks before the first frost. Generally early to mid September is a good time to consider in order to let grass roots take in the extra nutrients as they ready to slow their growth for the winter, and again after frost, usually sometime in November to help with winter feeding. Come spring you can also spread fertilizer lightly again after the first flush of growth occurs to avoid overfeeding, which can result in excessive top growth and shallower roots. .

What type of Fertilizer to Use

Nitrogen is the most important nutrient for grasses and should be spread at a rate of one pound per 1000 square feet of lawn, so you definitely want to use a nitrogen rich fertilizer such as a quick release nitrogen variety. You’ll also want to check your pH balance (soils should be slightly acidic), as well as phosphorus and potassium levels for adequacy to determine if you need to add sulfur for pH or other nutrients. These can be tested easily using a kit you can purchase easily online and at some garden centers.

Use the following link to calculate what you will need based on soil results.

When to Fertilize Warm Season Grasses

Warm season grasses grow best when the temperatures during the growing season average between 80 to 95 degrees, and go dormant in winter, turning brown for around three to five months depending on your climate. Dormancy occurs after the first frost.

Popular warm season grasses include:

  • Bermuda
  • Buffalo
  • Bahia
  • Zoysia
  • St. Augustine
  • Centipede

Warm season grasses are, as a rule of thumb, much easier to maintain than cool season varieties. They only need a feeding once in the spring after they have come out of dormancy, but are more easily damaged by fertilizer- and so waiting to spread nutrients later is better than earlier. If you are unsure if your grass is fully out of dormancy, consider waiting until you have cut it at least three times to be safe.

However, you can also feed periodically throughout the growing season and into fall if you feel your lawn will benefit from it. Determining if your lawn needs an extra boost from multiple feedings is as simple as running a soil test to see if nutrients are lacking, or if your grass is looking less than vibrant despite applying proper watering techniques. Warmer climates tend towards a quicker growth of vegetation, meaning more nutrients are used more rapidly.

What Type of Fertilizer to Use

Like cool season grasses, warm season grasses benefit the most from nitrogen rich fertilizers. Run a soil test to determine potassium and phosphorus rates as well, and see if you have a healthy pH. Knowing this will help you calculate your lawns particular needs and which fertilizer to purchase.

Fertilizing After Seeding or Overseeding

Fertilizing seeded areas should be avoided until the grass is well established. Many fertilizers contain a herbicide that keeps seed from germinating, and you won’t be doing your new seed any favors by attempting to ‘feed’ it so early on.

Once seed has become established, fertilizing is important to help get grass the nutrients it needs to get deep healthy root. But even so, do not fertilize until at least 4 weeks after germination to ensure all seed has taken root. And be sure to use a lower nitrogen feed for the first few applications so as to not give the weeds in the area a chance to choke out your newly forming grass roots. Instead, apply a general balanced fertilizer.

new sod lawn

Fertilizing New Lawn Sod

New turf, or sod, already has a healthy root system started, and so after laying your lawn, fertilizing is an important step to take to keep it growing and becoming established in the soil beneath the initial layment. First applications should occur at 4 weeks, and again at 8 weeks after instillation dates. After that a half pound of nitrogen every 1000 feet every four weeks is suggested until roots have grown well into the topsoil.

spraying a weed killer

Fertilizing and Weed Killer

Just like all fertilizers can be different, so can weed killers, so it really is recommended to treat your lawn with both separately rather than in a combined application. However, if you want to go this route, there are a few helpful steps to take to make your application a success.

Granular combinations are more effective for both feeding and killing unwanted vegetation due to it’s times release into the soils. It washes away less easily, and gets more to the roots, where it is needed. Be sure to apply after mowing the lawn that takes the heads off of the majority of your weeds, and makes them more susceptible to uptake the poisons that will eradicate them. Also avoid watering heavily after initial spreading. Instead, sprinkle with water lightly before and after to ensure grains begin to dissolve.

Lawn Fertilizer Troubleshooting

By following the above guidelines you should be well on your way to a healthy lawn, but for further help, remember a few key things during application so you aren’t asking yourself about fertilizer amounts, weather, or if you should feed before or after mowing the lawn:

Do not over apply your fertilizer. You do not want to burn out your grass. Even a little provides new nutrients to your grasses.

manual-fertilizing

Do not apply fertilizer if rain is in the forecast. You want it to get to the roots, and not be washed away by too much water. rain-forecast

Apply fertilizers after mowing your lawn, and not before in order to allow it time to absorb before the next cutting.

lawn-mowing

Mark Your Calendars!

Keep in mind that to properly fertilize your lawn you will need to make sure you have knowledge of your grasses to get started. I always struggled with keeping my lawn looking the way I wanted until I began to follow the simple fertilizing steps outlined above. To recap, remember you need to start with knowing what type of grasses you are growing.

  • Know your grass
  • Pick your dates
  • Choose a nitrogen rich fertilizer
  • Apply correctly
  • Fertilize newly seeded lawn or sod correctly
  • Use granular weed and fertilizer combos
  • Do not over apply or overwater!

Have any helpful hints and success stories? Comment below! Any questions? Feel free to ask and we will get back to you! And, as always, please share!

About The Author

Danielle McLeod

Danielle McLeod cuts a tragic figure in the High School English classroom teaching literature by day, and moonlighting as a writer and graphic artist by night. Published in a variety of travel magazines, and now a blog, Danielle enjoys coming up with home and garden projects to complete with her two young boys. A native of Michigan, she resides in Southeastern New Mexico with her variety of horses, poultry, and variable mix of rescue dogs (there’s a cat or two in there as well). In her free time she enjoys travel, art, photography, and a good book!

1 Comment

  1. Tyler Meredith

    It’s interesting that this article mentions that all fertilizers and weed killers being different. It makes sense that some might be harsher than others while others might be more organic. It’s something to remember when looking to have the yard sprayed just to ensure I’m getting one that won’t hurt the grass’s ability to grow.

    Reply

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