Ask a homeowner what their number one lawn concern is, and the most common response is “weeds.”
When a lawn care professional is asked what their number one lawn concern is for a client’s lawn, the most common response is “turf health.”
Both the homeowner and the lawn care professional have the same goal in mind: A thick, healthy turf.
Where do weeds come from and what is their relationship to a healthy lawn?
Developing a healthy, thick turf is 75% of battle in the fight against weeds.
Let’s start with defining a weed. A weed is anything growing where it is not wanted.
We automatically think of weeds in lawns or flower beds, but any plant in an unwanted location is a weed by definition. A weed is any unwanted, undesirable plant.
Some weeds can be pretty. Fields of henbit with their purple flowers are attractive. But, henbit growing in a Bermuda lawn is not desirable.
Spurge is a summer annual broadleaf weed that thrives in compacted dry soil. During periods of drought, it is common to find spurge growing along the edges of drives and walks where the soil is often compacted and dry.
Crabgrass is the most prolific summer annual weed. A single crabgrass plant will produce thousands of seeds. It is a weed that you are guaranteed to have in your lawn every summer if you do not apply a spring pre-emergent.
Weeds are not desirable because they compete with the desirable plant, your lawn, for resources. They steal water and nutrients. They rob the lawn of what is needed to be healthy. They interfere with the cosmetic appearance of your lawn. They spread rapidly when left unattended. And, one weed can produce thousands of seeds.
Weeds seem suddenly to appear. You can have a perfect lawn and all of the sudden it is as if weeds just magically showed up out of nowhere.
Weeds are very opportunistic. Give them a thin, bare area in a lawn and they will magically fill the void very quickly.
Weeds are the ultimate opportunist!
They grew wherever there is an opportunity!
Where do weeds come from?
Wind spreads weed seeds the most. April and May this year was one of the most consistently windy periods we have experienced. During the summer of 2020, the southern US experienced a massive Saharan dust storm. All those windy days and rare dust storms from the other side of the planet bring more than just dust. Wind distributes weed seeds from regions around the world into our lawns and landscapes. And, then on top of that there is an ordinary Oklahoma windy day scattering weed seeds from around your neighborhood or the native fields close to your home into your lawn.
Bird poop is another very common source of weed seeds. Birds’ primary food source is seeds and they are very good at depositing seeds around. Side note: Did you know the only way a seed from an Eastern Red Cedar can germinate is if it has passed through a bird. The blue-green berries (seeds) of Eastern Red Cedar attract birds, they devour them and scatter the seeds.
Rain is very good at distributing weed seeds, especially around the edges of the lawn as raindrops splash dust and weed seeds from the surrounding hard surfaces onto the lawn.
Seeds are also commonly carried onto the lawn by equipment, shoes, and pets.
This summer we have encountered a weed that we previously have not seen, marsh parsley. We have also had conversations with horticulturists about new weeds they are seeing this year. The common belief is they are a result of the excessive winds of April and May.
Environmental conditions and maintenance practices often bring about more weeds:
Seeds can also lay dormant for years and then germinate when the conditions are just right. A warmer than normal winter, a cooler than normal summer, an extended wet period, or even an extended dry period followed by heavy rain can change the environment just enough for dormant weed seeds to start growing.
Cultivating the soil in preparation for a new lawn or cultivating the soil in landscape areas can bring seeds to the surface where they will receive enough sunlight and water to germinate.
Marsh Parsley is a summer broadleaf weed that is new to our area. Most likely the consistently windy days of April and May delivered the wind seed to the area.
Pre-emergent herbicide applications with a quality product at the correct time are an important part of preventing the spread of weeds. But more importantly, is a healthy turf.
Poa Annua is the most common winter annual grassy weed. Pre-emergent herbicides help but don’t always prevent all poa annua from germinating. The best defense against poa annua is a healthy thick turf. Under trees, if you don’t have a healthy stand if fescue, most likely you will have poa annua.
Yellow rocket is a summer annual weed that was rarely seen in our area until just a few years ago. Now, it is very common in thin lawns, flower beds, and hardscape areas.
The best way to deal with weeds is to make sure your lawn has what it needs to grow and thrive:
Climate – Growing a turf best suited for the climate is important. If you are attempting to grow a type of grass that is marginal in central Oklahoma, you will most likely have a thinner turf and more weeds.
Soil – Very important to having a healthy turf. If the soil isn’t healthy, the turf will be weaker. With our tight clay soils, reduction of soil compaction through annual aeration is a big first step toward healthy soil.
Light – Attempting to grow a turf that needs at least 5 hours of direct sunlight, such as Bermuda grass, in shade will result in a thin tuft. It is important to grow the best turf for your light levels.
Water – An actively growing, healthy turf requires moisture, 1 to 1.5” of water per week during the heat of the summer. If you choose not to water and allow your lawn to go dormant during periods of drought, it doesn’t necessarily mean the lawn will die, but it often results in a thinner turf that is more prone to weed growth in the future.
Fertilizer – A thick, healthy, weed-free lawn requires a lawn that is properly fed during the growing season. If you apply pre-emergent herbicides at the right time but fail to feed your lawn, you can still expect to have weeds because of thin turf.
Mowing Frequency and Height – Lawn health is best when the lawn is mowed often enough that you are never removing more than 1/3” of the leaf blade and the lawn is mowed at the best height for the type of grass. For Bermuda in the heat of the season, 2 to 2.5” is perfect. For fescue lawns, 3 to 3.5” is ideal.
This Bermuda lawn was very weedy and thin when a regular lawn care program of well-timed weed control applications and fertilizer was started last year. After a full year, the lawn was thick and nearly weed free.
We believe at least 75% of a weed-free lawn is having a healthy, thick lawn.
Fertilizer, mowing, watering, and soil health are critical to weed control.
This summer is bringing us tough conditions. Truth is it isn’t just the drought and heat of this summer. It was a dry winter. And, before that, it was an extremely cold February. All will have an impact on the health of your lawn.
Our goal is to do all we can to help your lawn and landscape not only survive but thrive.
Our goal is to help you have a healthy lawn.
A healthy, weed-free lawn.
Lorne Hall
Hall | Stewart Lawn + Landscape
(405)367-3873