Chrissie Segars, Ph.D.-Turfgrass specialist and professor at Texas A&M AgriLife Extension in Dallas
Our recent how-to on why soil structure and soil texture are important to a thick, healthy lawn [you can read that story here] introduced some lawn care basics. That was just the start. One reader, David Pavlik, who does lawn installations and mowing and maintenance, suggested we give answers to often-asked questions about things like mowing height, aerating, dethatching, fertilizing, and whether to bag your clippings.
So, we turned to Chrissie Segars, a Ph.D. turfgrass specialist and professor at Texas A&M AgriLife Extension in Dallas. Chrissie specializes in educating communities on all things lawn care and best practices for the environment, backed up by scientific research.
What advice does Chrissie give to any homeowner who wants to create or maintain a lawn they’ll be proud of?
“The first thing we tell them is that what they might need to do is take a step back,” Chrissie says. “It’s human nature to want to care for things and a lot of times we see folks just doing too much: over-watering, over-fertilizing, over-applying chemicals. So, a lot of times we just try to talk to them about what kind of things they’re currently doing and see if they have a current management plan.”
Starting from Square One
“We need to meet every homeowner where they are. The first thing to do is an assessment of our lawn; figureout where we’re at and what our goals are.
“Somebody that is just starting out fresh, establishment is going to be their number one means of success. So, an appropriate beginning: having appropriate soil, bringing in the appropriate amendments, appropriate dirt work, and then bringing in grass – whether it’s seed or sod. Get those things established and that’s going tolead to a lot of success.”
If you’ve got an established lawn
If you’ve already got a grass and you ask, ‘What can I do to my lawn where it’s at?’, we need to assess what you’ve got going on: do you have a bad weed population? What percent of weed population do you have?”
Chrissie cautions that if, say, half your lawn is covered in weeds, you need an action plan before you attemptto kill those weeds.
“You don’t want to kill all the weeds and then have nothing on the ground because it’s not the appropriate time to put something down. It’s a lot of just understanding how the plant grows.”
“Spring is a key time for warm-season grasses, in terms of management,” Chrissie says, “doing those practices that can actually help a lawn recover, like aerifying, dethatching, those types of things because our warm-season grasses have spent the winter asleep.”
Spring isn’t the only time of year to focus on lawn management. There are management practices you’ll wantto do at different times of the year.
[Click here to read a Q&A transcript for more lawn care basics from lawn care expert Chrissie Segars]
“The spring and early summer is where we are recommending for you to do your most stressful types of practices – like dethatching or aerating – because it’s going to give your grass time to recover. We wouldn’t want to do that kind of stuff in the fall because it’s not going to have time to recover before the winter.”
Mowing height
Proper mowing height depends on what kind of grass you have.
“Bermuda grass, you can technically mow lower than a grass like St. Augustine,” Chrissie says.
On a common Bermuda grass, the recommend mowing height is 1.5-3 inches. For St. Augustine, 2-4 inches isthe recommendation.
“The lower you mow, the more often you are committing to mow,” Chrissie advises. “Use the one-third rule. That helps explain the frequency you want to mow your grass. Let’s say you’re mowing St Augustine at two inches. You want to stop from removing more than one- third of the leaf height, so we would want to mow it when the grass gets to no taller than three inches.”
You’ll know you’ve moved your grass too low when you notice discoloration.
“You may be injuring the grass to the point of no return,” Chrissie says. “That’s what we want to avoid.”
Rule of thumb: “We tell folks to set your mower at either the highest height it will go or one step below.
To aerate or not to aerate
“We do recommend aerification, especially if you have compacted soils, new lawns with limited organic matter,or lawns that are heavily or even moderately used,” Chrissie says.
Aerate in the spring, once the grass is greened up, but before it gets too hot out. “When it gets to 90-95degrees, grasses are not growing very well at that point.
“Aerification can release soil compaction. It can create opportunities for air movement and water movementdown in the soil.”
Not every soil is conducive to aerification.
“If the soil is really rocky, aerification is just not possible,” Chrissie says. “So you want to know your soil andknow if aerification is even going to help.”
What is thatch and when is it time to dethatch
“Thatch is an intermingling layer of stuff in dead material that has built up between your soil and between your grass,” Chrissie explains. “If you have an excess of thatch, you might walk out on your lawn and it might feel bouncy, like you’re walking on a mattress or small trampoline; you get a cushy feeling on your lawn.”
“What thatch can do…once it gets to a half inch or an inch, it can start impeding infiltration of water, even fertilizer, and it can harbor insects and diseases in that layer. So, we want to remove it.”
What type of grass do you have in your yard? Your independent dealer can help you with the right equipment you’ll need to remove thatch from various species. Chrissie says that dethatching doesn’t have to be doneevery year.
“It depends on how you use your lawn. If you’re establishing from ground zero, then I would say maybe 1–3-year mark and depending on the status of your grass when you got it: how healthy it was, how ‘thatchy’ it was.That is a goal that we would look at.”
“The important thing is…to get that material off your lawn. You don’t want to mow it or blow it back onto yourlawn.”
Bag clippings or leave them on your lawn?
When you cut grass at regular intervals at an appropriate mowing height, Chrissie says they have found that returning clippings back into the grass increases nitrogen by 50%. “So, we can cut down on our fertility if weare mowing regularly and we are returning our clippings.”
When should you bag?
A lot of people say, ‘I have a lot of weeds out there and I’m trying to get rid of them,’ but they may be too mature and it might not be the appropriate time to spray a herbicide,” Chrissie cautions. “That’s when you’ll want to be bagging your clippings and removing them because as soon as our weeds start flowering, any reproductive structure they put out, that gives them a chance to spread those weeds seeds.”
Fertilizer
“In general, we do recommend for grasses to have a certain amount of fertilizer for them to be at their best.”
“We typically recommend to make that first fertilizer application – and we give two options for the homeowner to follow – one is that you wait until 4-6 weeks after your last historic frost in your area. For example: let’s say we could have a frost around Easter, so around the first or second week of April. We’ll want to wait at least four weeks after that because that ensures we’re not going to have another frost; we didn’t wake our grass up tooearly.”
“The other thing we tell folks is to wait until your lawn has been mowed at least twice. So, if you are mowing your grass and you’re getting clippings off of it, that means the soil temperatures are warming up enough for that grass to grow; we typically start seeing root activity again from warm-season grasses when the soil is 50-55 degrees.”
For the last fertilizer application of the season, flip it around.
“It should be 4-6 weeks before the first average frost in your area. So, say you traditionally get a frost somewhere around November 1-15. We should stop our nitrogen fertilizer application 4-6 weeks before that time frame to give our grass time to uptake our last bit of nitrogen and conserve it for the winter when it goesinto dormancy.”
“If we make our fertilizer application too late, especially when the soil temperature is below 50-55 degrees, wesee our root activity pretty much stop at that point, so if we’re putting nitrogen or another type of fertilizer down, we will see a lot of that lost to the environment because the roots are just not active and are not taking it up.”
[What are some mistakes and myths about proper lawn care? Click here to find out what lawn care expertChrissie Segars says]
Stating the obvious, Chrissie recommends that you think about these basics to lawn care, rather than doingnothing more than mowing.
“A healthier lawn, at least, has some kind of basic management on it,” Chrissie says. “Whether or not you do one fertilizer application a year, your grass is likely going to look a lot better if you do just one to two fertilizerapplications a year, rather than zero.”