It’s a combination of good cultural practices: watering, fertilizing, aerating and dethatching that make for a healthy lawn. “If you kind of cut corners on one or two of those, it’s going to counteract what you’re trying to do,” says Shawn Karn, agronomic manager of Nutri-Lawn Corp. in Toronto. Here are his best practices for cultivating deep, strong roots.
Dethatching
Thatch is one of the most common problems Karn sees in home lawns, and while a little bit of thatch isn’t harmful, a half-inch or more can be a serious problem. Grass roots become caught in the thatch layer and can’t get down to the soil they need. Dethatching will eliminate that barrier, allowing healthy root growth.
Aeration
Karn’s philosophy on aeration is “the more the better,” but recognizing that his customers only have so much money to spend, he promotes an annual aeration either in the spring or fall. “I always say, ‘You can’t poke enough holes in a lawn.’ If you own an aerator or had one at your disposal, you’d probably do it every month,” he says.
Aerating the soil creates a nice, easy path for roots to grow without having to push their way through the soil. “Every time we’re poking a hole, we’re creating a channel in the soil for the roots to fill that void in and grow deeper down,” Karn says.
Aeration is a great tool for lawn care operators who encounter shallow roots in a lawn. After ensuring the proper watering and fertilization, aeration and overseeding can fix the problem. And they go hand-in-hand, Karn says. “You poke a hole; the grass that’s there will kind of grow sideways and fill those holes in and if you seed at the same time, now you’ve got a place for that seed to fall down those holes and you’ve got the good, the ideal seed to soil contact as opposed to just throwing grass seed in a bunch of grass.”
Watering
Once you know your site and soil conditions, the next most important thing to look at is irrigation, Karn says. Watering deeply and infrequently is the key to deep roots. Shallow, frequent watering will produce the opposite effect.
“You’re just kind of trying to train the roots of the plant to go longer periods of time without water so they actually have to dig down and search for the water. If we’re only watering once or twice a week, the roots have to chase that water down and it encourages it to grow a lot deeper than if you were giving it water every day.”
Mowing
Karn offers the following tips on proper mowing for good root health:
- Never remove more than a third of a leaf blade at a time to keep the grass from going into shock.
- Maintain a 2 ½- to 3-inch height of cut.
- Always use a sharp mower blade.
- Mulch your clippings to reincorporate the nitrogen back into the soil.
- Change your mowing patterns to avoid tire rutting.
- Avoid mowing wet grass to make sure you’re getting a clean cut and to avoid clumps of grass clippings.