Attack of the killer lawn

July 15, 2008 2:44 PM

I need advice on how to discourage grass growth without killing it outright. Any thoughts?

I have a section of my yard with very agressive lawn growth. It's a small strip in the back where apparently there is an underground spring flow path. The land has soil on it, and then about 4 or 5 feet down is bedrock, so this spring "flows" along the soil and bedrock and makes the back 10 feet or so of my yard a perpetually moist growing factory. As a result, the rest of the yard has about 3" of grass height right now, and the back bit is pushing 7". I was away this last week, so that 7" growth is from the last 14 days or so. Is there any way to "discourage" the lawn from such aggressive growth or otherwise slow it down? I don't necessarily want to kill it (though I probably wouldn't shed any tears if that came to pass accidentally), just get it more in line with the rest of the grass.

posted by barc0001 to home & garden (8 comments total)

If the strip is in a place where other plants won't look strange, I would say you should get rid of the grass and plant something that's wet-tolerant in its place. Here's one list of plants that might work, and here's another.
posted by cabingirl at 3:09 PM on July 15, 2008

If you cover it with black plastic (or really, anything that is weatherproof and sunlight won't pass through) you can effectively kill a large area of grass. I imagine that if you cycled it, you could merely stunt it's growth, but you would then have large sheets of plastic covering parts of your yard instead of lawn.

Otherwise you may want to see if you can find some other kind of ground cover that won't attain the same height. We are using clover for this in parts of my yard.

Beyond that you could get a robotic mower and just let it run.
posted by quin at 3:40 PM on July 15, 2008

I would go for an alternative ground cover, which ought to provide some good landscaping options. Or, you can dig everything up and channel that spring through a drainage ditch filled with stone, cover that with heavy permeable groundcloth, then soil and reseed grass. The surface will no longer be wet and grass will grow normally.
posted by beagle at 3:46 PM on July 15, 2008

There are plant growth regulators out there. I work in the turfgrass industry, and one I've used with great success is Primo Maxx, made by Syngenta. It's not cheap, and may be restricted use in your area. You might be able to hire a lawn service or other licensed applicator to treat the area for you.
posted by Shohn at 5:48 PM on July 15, 2008

The root of your problem is the water, not the grass. Could you improve the drainage with some tiling?

On related note, I was talking to somebody the other day who had the reverse problem - a random section of grass which was not growing well compared to the rest of the lawn. After trying various fertilizers, they finally went out to dig up the bad grass and lay new sod.

First shovelful hid something hard... a 4x8 piece of plywood the exact size of the troubled patch lay about 3" under the surface.
posted by jpdoane at 6:30 PM on July 15, 2008

I don't necessarily want to kill it (though I probably wouldn't shed any tears if that came to pass accidentally), just get it more in line with the rest of the grass.

If the water supply is significantly different, you will never succeed in matching the areas up. You might find some chemicals that stunt the growth, but you'll probably have to keep applying it, it will be hard to make sure that you add just enough but not too much, and it might spread to surrounding soil, causing bare patches in the drier area.

You'd probably save yourself bother and money if you covered it with black plastic to kill all the grass and weeds under it without leaving chemicals in your soil, and then planted something else there that you wouldn't want or have to cut. Results: attractive (and tasty?) planting + less maintenance = happier you. Make a list of fruits, veggies, and herbs you like, then find out which ones are perrennial (no replanting every year) and are suitable for wet ground. Or maybe just flowers for yourself or others?

a 4x8 piece of plywood the exact size of the troubled patch lay about 3" under the surface.

And what's under that?
posted by pracowity at 11:36 PM on July 15, 2008

I think you're looking at this the wrong way. It's not so much that you want to kill your lawn, you just want it to be less aggressive.

First, back off on whatever fertilization you're doing. Just as you should cut your feeder rate in half when you hit shade, cut it back here because the grass obviously doesn't need as much. (In fact, I wonder if half the problem isn't so much just water as it is nitrogen runoff from another lawn. You may want to look uphill and see what your neighbor is doing.)

Second, you actually run the risk of moss, algae, and a variety of grass diseases in this wettish area. The grass roots should be rotting if it's always wet. (Partly why I suspect the culprit is not an underground stream per se.) For the overall health of your lawn you may wish to channelize any surface water and perhaps even dig a dry well (anything from a casual hole filled with gravel to a concrete manhole-like structure can be used).

Third, you may want to amend the soil -- either in the fast or slow growing area. Do standard pH soil tests in both areas, sampling separately from several different points and combining into one sample for each. It's possible that your regular lawn is just too low in pH, and a layer of lime would help bring the rest of it into a more similar growth pattern. For the high pH area (presumably where the high growth is), an amendment of sulfur is recommended instead.

Fourth, you could change this to another type of planting. You could add a slower-growing grass variety when you reseed in the fall. Or a groundcover instead. Or a planting bed. (How about some hostas?) You could just overseed with some clover which will displace some of the high-growing grass (but most people consider clover an invasive semi-weed these days).

Fifth, you could try adding volume to the soil and raising it up a bit so it isn't as close to the water underneath (if that's the real problem). Sand and gravel in irregular spreading over the source of a summer will make it a little bit higher and less wet. If there is any accumulation, the gravel will displace water that could have accumulated there. You could also add clay but this is a bit less convenient (and usually people want more soil and less clay).

You could also choose to accept a bit of variety in your lawn.
posted by dhartung at 1:10 AM on July 16, 2008

I have an area near the condensation lines for my AC that is continuously moist and did what pracowity suggested; some herbs and a few pepper plants do great there now with very little maintenance. There is a severe drought where I live and watering is restricted, so I had incentive to take advantage of the moisture rather than mitigate its effects.
posted by TedW at 4:09 AM on July 16, 2008