Why is a Spring Pre-Emergent So Important?

Spring Pre-Emergent.jpg

There are many reasons for weeds.  Weeds can be the result of poor growing conditions due to lack of moisture, weeds are typically worse when soil is compacted, and weeds are always more prevalent in thin turf.   

But, there is one very important thing that will make the biggest difference in the amount of weeds you have this year – the early spring pre-emergent lawn care application.

Hall | Stewart Lawn + Landscape has been actively applying the early Spring Pre-Emergent for the past few weeks.  Our goal is to make sure all of our clients have taken the necessary step to prevent weeds this year.

We get involved in a lot of conversations about weeds and wanted to share with you a few of the most common questions.

Why is the early spring pre-emergent so critical? 

Summer annual weeds come up every year.  They germinate, grow, reseed, and die all in one year.  They can be booth grassy weeds and broadleaf weeds.  A quality pre-emergent herbicide will prevent many types of weeds.  But, the most aggressive annual grassy weed is crabgrass.  If you had a single crabgrass plant in your lawn last year, or your neighbor’s lawn had crabgrass, or your neighbor’s neighbors had crabgrass, there is a real strong chance you will have crabgrass this summer if you do not apply a pre-emergent to your lawn this spring. 


Why am I so sure you will have crabgrass if you skip the early spring pre-emergent application?

A single crabgrass plant produces thousands of seeds.  Because crabgrass is so prolific, even the nicest lawn in your neighborhood last summer can be full of crabgrass this summer if a pre-emergent is not applied this year.    

Mid summer lawn that did not have any pre-emergent in the spring.  

Mid summer lawn that did not have any pre-emergent in the spring.  

Because crabgrass is fast growing and spreads quickly,  it can have a dominant presence in your lawn by May without a spring pre-emergent.

Because crabgrass is fast growing and spreads quickly, it can have a dominant presence in your lawn by May without a spring pre-emergent.

What is the best timing of the first lawn care application?

With thousands of seeds laying dormant in the soil, as soon as conditions are right, germination will begin.  Germination of crabgrass occurs typically in mid March in central Oklahoma.  The key determination is soil temperature.  When soil temperatures consistently reach 55 degrees germination occurs.  This week, soil temperatures in the Oklahoma City area are in the mid-40s.  For the best prevention of summer annual weeds, your first lawn care treatment needs to be applied by the end of February.

IMG_3337 edit.jpg

Will one pre-emergent application per year be enough?

Crabgrass is one of the first annual weeds to germination each spring, but it does not germinate all at once.  Germination of seed will continue throughout the summer.  Other summer annual grassy weeds such as, goosegrass, foxtail, and sandbur will germinate soon after crabgrass.  Knotweed and spurge are summer annual broadleaf weeds that will germinate even later.  Summer annuals germinate from mid-March through early summer.  Most pre-emergent herbicides will not provide coverage the entire summer growing season.  The herbicide creates a blanket over the soil to prevent seeds from germinating. Rain, irrigation, foot traffic, all combine to break down the herbicide.  Therefore, full summer control is only obtainable if you repeat the application again in late spring: April-May, approximately 6-12 weeks after the first application.

Does a pre-emergent need to be applied as a liquid or can it be spread as a granular?

Pre-emergent herbicides come in both forms and for the best results the product needs to be applied evenly to the lawn to create a weed barrier.  With either product, watering the product into the root zone is important.  Always follow directions.  When doing it yourself never over apply a pre-emergent as it can stunt root growth. 

Why are pre-emergent sprays green?

Actually they are not.  Some lawn care companies add dye to their herbicide to use as a marking pattern.  We are not a proponent of using a dye.  Most pre-emergent herbicides have a light coloring that aid the lawn care professional in applying the product evenly to the surface.  We find dyes messy, they give the natural landscape an artificial look, and add an unnecessary chemical to your landscape.


Most importantly, if you have not applied a pre-emergent to your lawn yet this year, please do not delay. 

If you need assistance in making sure your lawn is weed free and healthy this season, please call Hall|Stewart Lawn + Landscape at (405)367-3873.


Lorne Hall