The most feared weed... Crabgrass!


Crabgrass is so well known — it’s the most talked about and most feared of all weeds.  Most people are so captivated with the fear of having crabgrass take over their lawn that it is common for them to refer to any weed as the dreaded “Crabgrass!”

With March as the critical point in preventing crabgrass, I thought we should hold a quick educational seminar on crabgrass.

What is crabgrass?

It is a summer annual grassy weed.  This means that it dies every year and comes back from seed the next year.  Just like the name suggests, it spreads low to the ground.  It is yellowish to light green in color.  Crabgrass is a prolific grower and if left unattended will rapidly dominate turf.  It can be found in almost every turf and landscape setting during the summer months if not properly managed.

What is the crabgrass life cycle?

Crabgrass germinates every spring when soil temperatures reach 55 degrees for 2-3 consecutive days.  Typically, this occurs in central Oklahoma during the first week of March.  This year, soil temperatures are lagging with a current temperature of 50 degrees in central Oklahoma.  Last year, crabgrass germination started the last week of February.    During late spring and summer, crabgrass grows faster than turf grass and thrives under stress conditions of drought, heat. and low soil fertility — when turf is struggling.  Crabgrass dies in the fall after the first hard frost.  But before it dies, one mature crabgrass will produce thousands of seeds. 


Crabgrass seedling


Early Summer Crabgrass


Mid-Summer Crabgrass

What is the best way to control crabgrass?

Prevention is the key to crabgrass control.  A pre-emergent herbicide must be applied before soil temperatures reach the magical 55 degrees.  If Forsythia is blooming, it is a clue that crabgrass has started to germinate.  In addition to applying a pre-emergent, thick turf development is the key to reducing your exposure to crabgrass.  Sunlight is required for crabgrass to germinate and a thick turf will limit the amount of light reaching the soil surface.  A good turf maintenance program during the season consisting of regularly mowing, correct amounts of water, timely fertilizer, and annual aeration will produce a think lawn that is less susceptible to crabgrass invasion the next spring.

Will one pre-emergent application be enough?

Pre-emergent herbicides work by creating a barrier over the soil surface.  The barrier gradually weakens over the season from foot traffic, mowing and periods of heavy rain.  The edges of the lawn are the first to breakdown.  Additionally, crabgrass will continue to germinate throughout the season.  It is recommended that a second application be made in April through May for season long prevention.

If crabgrass is only a warm season weed, then what are the weeds in lawns now?

Just like crabgrass is a summer annual weed, there are also winter annual weeds.  The most popular winter annual weed is poa anna.  It is a cool season grassy weed that first germinates in early fall about the time we get our first few cool nights.  To have a clean lawn coming out of winter and going into spring, two fall pre-emergent applications need to be put on your lawn – one in early fall and one in late fall.

If you haven’t put a pre-emergent on your lawn yet this spring, is it too late?

This year, because of the cooler weather it isn’t too late.  But, you must get it done very soon!  Also, it is never too late to start preventing weeds.  Weeds are always germinating.  Even if you are late with the application, it is better than not doing it at all.  Additionally, the best pre-emergent herbicides will control annual weeds in the first stage of growth.  Always use a quality product or service for the best results.


The Best News About Crabgrass

If you are a subscriber to a Hall | Stewart Lawn Care Program, either the 7-Step Weed Control & Fertilizer or the 4-Step Weed Control Only, you have already had your 1st Pre-emergent Application to prevent crabgrass this year!

If you are not a subscriber to a Hall | Stewart Lawn Care Program, please contact us.  We want to make sure you receive timely pre-emergent herbicides to stop weeds before they start wreaking havoc on your lawn.  Preventing weeds is much easier on your lawn than trying to control them after they are up and growing.  Once weeds take root harsher products must be used that may slow turf development.

If you have questions or would like additional information about crabgrass and how to prevent it from taking over your lawn, please contact us at (405)367-3873.

Lorne Hall

Hall|Stewart Lawn + Landscape