Nutsedge News

Nutsedge: The Superweed


The best way to describe nutsedge is “superweed.” Unlike other broadleaf weeds, this sedge has a robust root system made of nut-like tubers called nutlets. The nutlet stores a high amount of energy for the nutsedge to use in its lifecycle. With their grass-like leaves, sedges can be difficult to distinguish within the lawn at the beginning of the growing season. In the hot, humid, sunny days of summer, however, it grows faster than most grasses and even begins to flower. It is easy to distinguish only a few days after mowing by the lighter green leaves shooting up quicker and taller than the grass surrounding it.

Because of its reliance on heat and light, nutsedge does not do well in shady areas. Nutsedge thrives particularly well in wet soil and will invade areas where it didn’t grow in the past because of the amount of moisture retained in the soil. Increased soil moisture could be from poor drainage, too much rain or irrigation, or even water run-off from a leaking hose. If any of these things can be modified, that might help. Otherwise, a fall aeration may be necessary to relieve soil compaction, which will aid in better overall drainage.


How to Treat It

In the lawn and landscape industry, nutsedge continues to be an issue we tackle head-on. Unlike annual grassy weeds like crabgrass, we have no pre-emergent herbicides that allow us to treat the sedge before it sprouts. Instead, we can only treat nutsedge post-emergently while we can see it. Because of the stored energy in the “superweed” nutlets, it is not uncommon for nutsedge to recover after we treat it and reappear after only a couple of weeks. Even hand-pulling is only partially effective unless you remove the entire root system.

It often takes several herbicide applications entirely control this tenacious weed until it dies off in the cooler fall temperatures. Even then, there still might be enough stored energy in the roots for it to return the next year. While we are happy to treat the nutsedge when we find it in the yard, or when we receive a service request, there may be circumstances where further treatment is no longer advisable. If herbicide could burn the lawn due to heat or drought, we recommend postponing chemical treatment to prevent damage.


For your reference, consider reviewing the links below for additional information:

Mowing Tips: The No 1 Thing for Lawn Health

Mowing Tips for a Healthy Lawn

Mowing at 3-4 inches is important for health

Proper mowing is the most important cultural practice you can do for a healthy lawn. It is important to state that mowing isn’t necessarily something we have to do to keep the lawn healthy. In reality, the natural growth habit of tall fescue is for it to grow several feet tall. We force it to be 3 to 4 inches high because we want that manicured look and because of all the other benefits we receive from a well-manicured lawn, including pest control. With that said, it stands to reason that there are certain things we have to do to minimize the damage we cause when we mow. Here are some mowing tips and “must do’s” when maintaining lawn during the growing season.


Never mow more than 1/3 of the grass blade at one timeMowing frequency-Never let the lawn get too tall. You should maintain your cool season lawn at a 3-4” height. Never remove more than 1/3 of the blade at any one mowing. If you are mowing at 3 ½” you should mow when the lawn is no taller than 4 ½”. Taking less off at one time is always better.

This is a picture of a lawnmower race.

Confirm the height you are mowing. Mow a small patch and use a ruler to measure the height of the mown area. Do not rely on the settings on your equipment. (Ask us for a free mower measure to stop the guessing!)

Never mow during the heat of the day, especially on windy days. Mowing during the heat of the day can severely dehydrate the grass, and it will turn brown.

Use a mulching blade to return nutrients back to the soil when you mow.

Return your clippings. Grass clippings are 80% water and break down readily when they contact the soil. Use a mulching mower blade to cut the clippings into tiny pieces that will return to the soil. If you bag, you are taking away the very nutrients your lawn needs to grow.

Maintain a sharp mower blade. A dull mower blade will shred the tips of the grass blade giving the lawn a whitish look.

Check that the blades are installed properly. You would not believe how many mowers we find with the blades installed upside down.

Be careful when using a large garden tractor if the soil is wet. Lighter, walk-behind machines are preferred during the summer months. Walk across the lawn to judge the saturation of the soil before you mow. If in doubt, wait another day or until the lawn dries out some.

Be careful not to trim to short with a string trimmer.

String Trimmers. Most people think that the edge is supposed to be very short or even scalped, and the result is often a bare area which will fill in with weeds and crabgrass. Always be aware of what you are doing with the string trimmer. Do not trim too short.

How Does Lawn Striping Work? The stripes that you see on a lawn or athletic field are caused by light reflecting off the blades of the grass. They are created by bending the grass blades in different directions. When the blades are bent away from you, they appear to be lighter in color. When they are bent toward you, the shadow creates a darker hue.

Mow in opposite directions to create an attractive striping pattern.


Too Late for Crabgrass? When is the best time to treat?

The best way to control crabgrass is to kill it before it grows with a pre-emergent herbicide, but when is it too late to treat? Unfortunately, there’s no single definitive answer to this question. The short answer is to apply it before the crabgrass has a chance to germinate. The longer answer is that it depends on the weather and which pre-emergent is being used. Pre-emergent herbicides work by creating a chemical barrier that kills the crabgrass when it germinates. Some pre-emergent products provide some post-emergent control as well. Determining when a seed germinates depends on many variables in the environment. For crabgrass, the biggest variable is temperature. Crabgrass only germinates at sustained soil temperatures above 57°F at a one-inch depth. The best way to track the soil temperature is with growing degree days (GDD). Because it is tough to track soil temperatures without specialized equipment, we can use air temperature. Air temperatures will usually need to be at around 50°F for 200 degree days for germination.

200 days! That sure seems like a long time! That’s a common misconception that sometimes even confuses our office staff, but GDD isn’t just based on a calendar. GDD is based on a formula calculated by monitoring the median temperature. When the median temperature (High plus low divided by 2) for a day is above the range needed for germination, the number of degrees above that point is added to the GDD. For example, if the air temperature is at 52°F one day, 53°F the next day, and 49°F the day after that we have 5 GDD for that time period (there’s no such thing as negative degree days because plants can’t un-grow). It’s important to remember that areas in full sun or next to pavement will be warmer, and areas in the shade will be cooler than the average, so you have to take that into account with your own lawn.

Crabgrass Growing Degree Days Formula
(GDD Formula1)

All this math is a major pain just to find out if it’s too late to apply your pre-emergent crabgrass control. The rule of thumb that many landscape professionals used to go by was when the forsythia starts blooming. These days we have meteorologists help us out. To track the GDD yourself go to and follow these steps2:

  1. Enter your zip code (not all locations are included, check nearest weather station to your site) and hit enter
  2. Click the “custom” tab/button below the date
  3. Enter the start date below the word “from” (ex. Jan. 1) and the end date below the word “to” (current date)
  4. Hit the get “history” button
  5. Read your growing degree days (base 50) in the ‘Sum’ column (=Cummulatlive DD to date for the year)

Of course, the easiest way to make sure your pre-emergent crabgrass control gets applied on time is to call MRW Lawns at 301-870-3411 and let us take the work and worry out of having a real wonderful lawn.




P.S. If the growing degree days are over 200 in your area, don’t panic! There are post-emergent products that can help control crabgrass, even when fully grown; and in the worst-case scenario, crabgrass is an annual weed, so you’ll get another crack at it next year!

Should I seed my lawn this spring?

We get questions about spring lawn seeding every year. Many people, especially grass seed producers, recommend it, but it may not be the best option. While we can aerate and overseed in the spring, we recommend waiting until the fall for two main reasons. First, the weather in the spring and summer is challenging to seed and new grass. The spring weather can be unpredictably warm or cold, and grass seed needs soil temperatures for germination that are far from guaranteed. Additionally, the grass is in the early stages of growth during the heat of the summer, leaving it susceptible to disease and heat and drought stress. For these reasons, spring lawn seeding is less successful than fall seedings. The second reason is weeds, namely crabgrass. Crabgrass is the most important weed to control throughout the lifetime of the lawn, especially in the first few years of treatment. Because of this, our first application of the year includes a pre-emergent crabgrass control which stops the crabgrass seeds from sprouting by creating a protective barrier of herbicide that kills the crabgrass before it can reach the surface of the soil. It also prevents desirable turfgrass from sprouting, making seeding and crabgrass control almost mutually-exclusive. (more…)


The weather man is calling for BEAUTIFUL WEATHER! over the next several days. Sunny skies with no rain in sight for the near future. While you are making your plans to take advantage of the sunny skies, don’t forget to give the lawn some attention. It will need some water from you. Go to our website and review how to best take care of the lawn as the soil water bank starts to dry up. (more…)

Just in Time for Christmas! MRW Lawns Gift Cards Available!

When your friends and family ask you what you want for Christmas, tell them to buy you the Gift of GREEN this holiday season! MRW Lawns, Inc. is now offering gift cards. With an MRW Lawns, Inc. gift Heart of Grasscard, you can purchase valuable services like lawn fertilization, weed control and pest control for the outside of your home. This gift card can be used for existing services as well as new services. Regular treatments are a sure way to create a beautiful usable outside space for entertaining friends and family on those long holiday weekends or anytime. They help create a safe environment for the kids and the family pets, free of weeds and harmful insects. (more…)

It’s a Beautiful Day!

It’s a beautiful day here at MRW Lawns, Inc. The low humidity and nice temperatures allow for some good drying after the torrential storms on Saturday. Enjoy it while it lasts, and be sure not to let the lawn get too tall. Now, it is important not to mow when the soil saturated, but try not to let it get too tall, and mow it twice if you have to to remove excess growth (for example; the lawn gets to 7″ and you want to mow it to 3″). (more…)