Learn why cutting your grass super short is not a way to get around lawn maintenance, and can in fact be detrimental. Get tips on the ideal grass length for summer, how much and how often to water your lawn, and why the most efficient way to mow a lawn is in a circle.
LESLIE: Well, if you think the best way to save time and energy when cutting the grass  is to set your mower as low as possible so you don’t have to mow that often, you might be surprised to find out that that can actually end up being more work in the long run.
TOM: That’s right. There’s a method to cutting grass that, if followed, can really improve both the look and the health of your lawn. And here to give us some tips is a guy who has spent many years behind a lawnmower  and a hedger and a trimmer and a chainsaw and just about any other landscape tool you could name: Roger Cook , the landscaping contractor on TV’s This Old House .
ROGER: Thanks for having me.
TOM: So, most people don’t really give much thought to cutting the grass. And as Leslie said, they figure the shorter they cut it, the easier it’s going to be to maintain that lawn. Not true, though, huh?
ROGER: Not true at all. The shorter you cut the lawn, the more chance it has of getting scalped or getting weeds that come into the soil.
TOM: And so that’s just not going to help the health of the lawn, it’s not going to help the appearance of the lawn and it’s going to ultimately be more work. Because not only do you have to get that grass to grow again, you’ve got to get rid of all the weeds that you allowed to get in between all that grass.
ROGER: Right. And it’s amazing to know that the longer a grass is, it creates a little bit of shade and it actually stops the weeds  from coming in. And it also transitions during the year.
I don’t cut the lawn short in the spring but I cut them at a medium-low height.
ROGER: And then, in the summer, I actually cut them higher. When they’re cut high, it shades the root system and helps it from drying out all the time.
There’s also a correlation between how deep the roots grow with how long the leaf of the grass is.
TOM: That’s funny because you never think of grass as a shade plant, right? But it really does shade itself.
ROGER: And cool it off.
TOM: And cool it off, yeah.
So, what about whether you’re cutting it by hand, say, with a push mower  or you’re using a gas mower? Does it make a difference?
ROGER: It’s the right tool for the right spot. The whole trick to mowing a lawn is to cut out where you stop and make a corner and come back.
So if you’re using a big rider mower on a little area, that’s all you’re going to do is stop and turn, stop and turn. And if you’re using a little mower on a big area, it’s just going to take you forever to make the passes. So finding the right tool for the right job is important.
LESLIE: Now, is there a benefit to waiting X amount of hours after watering? Or do you not mow on days that you water? Is there any science to that?
ROGER: Well, it’s common sense more than science. You wouldn’t – believe it or not, but you can actually wear down tracks in the grass if you water it when it’s wet or you do the same pattern over and over. That can really become a problem.
What we do is we change the pattern every week. Usually, we’ll go the long way, the next week we’ll go the short way, then we’ll cut it at a 45 and then a 45 the opposite so we don’t get any compaction of the soil.
TOM: So how do you get the beautiful, crisscross diamond pattern that you see in the ballfields?
ROGER: Oh, they drag something behind the mower.
TOM: Oh, is that right?
ROGER: Yeah. It pulls …
LESLIE: Oh, really?
TOM: I didn’t know that.
ROGER: Yeah, it pulls all the grass in one direction and that’s what gives it the look. And then they can come by at different angles and change the direction going the opposite way.
TOM: That’s the same way the space aliens make crop circles, right?
ROGER: Yeah. Yeah, no. But if your lawn allows it, the best way to cut a lawn is in a circle.
ROGER: Because if you start in the center and work out, you’re not making any corners, you’re not stopping. It’s the most efficient way of …
LESLIE: You’re going to be really dizzy but …
ROGER: That’s OK. It’ll look good. That’s all that matters. Dizzy? Nah, we can handle dizzy.
TOM: We’re talking to Roger Cook. He’s the landscaping contractor on TV’s This Old House.
Now, let’s talk about clippings. What’s your advice on clippings? Do you leave the clippings? Do you collect the clippings? Do you need a mulching mower to leave the clippings?
ROGER: I would love for everyone to leave the clippings on the lawn but there are times when you can’t: when it’s too wet or the grass is actually so long that when you cut, it leaves it on the top of the lawn.
TOM: Right. OK.
ROGER: It’s very important that if you’re going to try to leave clippings, you have to use a mulching blade on your mower. If you just mow your lawn with a regular blade, you’re going to leave clumps and those clumps are going to kill the lawn.
If you can’t leave it on the lawn, which is – I would love everyone to do. If you collect it and put it into the compost pile , well, that’s the second-best thing you can do.
LESLIE: Now, what about watering? How much water does the lawn  really need and what’s the best way to gauge that?
ROGER: There’s so many different factors – sunny, shady, type of lawn, type of soil – that you have to feel your grass out a little bit. The basic rule of thumb is 1 inch of water per week. And what I tell everyone is I like to break that up into two doses. Really, water it so that the water goes down deep into the soil.
The other thing is that if you water every day, the root system will become lazy and just stay in the top. So if something happens and you don’t water it, it’ll dry out very, very quickly.
TOM: Good advice. Roger Cook, the landscaping contractor on TV’s This Old House, thanks so much for stopping by The Money Pit.
ROGER: My pleasure. Thanks for having me.
LESLIE: Catch the current season of This Old House and Ask This Old House on PBS. For local listings and step-by-step videos of many common home improvement projects, visit ThisOldHouse.com .
TOM: And Ask This Old House is proudly brought to you by Mitsubishi Electric Cooling & Heating. Live better. Go to MitsubishiComfort.com.