No good to touch the green, green grass at home . . .

October 10, 2007 10:43 AM

How can I kill the grass currently growing in our backyard? We live in the Northeast, and we have a small (15' x 40'?) patch of lawn in our backyard. I'd like to kill all the grass there, and replace it with thyme as a groundcover. I've already found a source for the groundcover.

We're not so crazy about the grass. It's bermuda grass? Or whatever your garden-variety grass is, we don't care. I've hated grass lawns ever since I was tasked with mowing the lawn in the house I grew up in. Grass makes us sneeze, it makes us itch, and we don't like it.

We do like thyme as a groundcover, because it's soft, because mosquitoes don't like it, and because it'll make our yard smell yummy. We'd like to plant it next spring. (Because I'm html-challenged, I'll just offer this link for more info on thyme as groundcover: http://www.mountainvalleygrowers.com/groundcoverthymes.htm)

However, the helpful folks at Mtn. Valley tell me that "we need to kill the grass before we grow the thyme." Apparently grass is very hearty, and will likely strangle much of the thyme we plant as groundcover. My question to the green is this: how can we kill the grass currently in our backyard, but not poison the ground we'd grow the thyme out of? It seems to me that Round-Up and other herbicides would only be half-useful to us, because while it'd get rid of the grass, it'd also make it difficult for thyme to grow, no?

If you've replaced your grass with a non-grass groundcover, please post your tips here. If you've brought an organic holocaust to your own grass-infested lawn, how did you do it? All the other posts here I found have to do with maintaining or mowing grass . . . who can show me how to murdalize it??

We'd appreciate any tips you might have with when to plant groundcovers, too. Mtn Vly tells us to do it in the spring, but what says MeFi?

posted by deejay jaydee to home & garden (19 comments total)

more on thyme as a groundcover in case my attempt at posting the link isn't clear above.

(btw, mods, could we maybe get tools to embed links when we post our questions?)
posted by deejay jaydee at 10:45 AM on October 10, 2007

Get large tarps and cover the grass for a month or two. Without light it will die. In the hot sun even weed seeds will be killed, but it is probably too late in the season for that.
posted by caddis at 10:48 AM on October 10, 2007 [1 favorite]

Get a sod cutter and slice the grass and roots off the topsoil.
posted by Gungho at 10:52 AM on October 10, 2007

Caddis has what is pretty much the easiest route. It's not pretty, but it works. And starting now would put you well-placed to plant your thyme in spring.
posted by katemonster at 10:57 AM on October 10, 2007

We sheet mulch, essentially taking large cardboard boxes broken down in to their flat parts, laid over the grass, 4 inches or so of topsoil/whatever and plant the thyme.

Gets rid of the cardboard (non waxed only!) and it will kill the grass underneath. This is what we do to kill areas of the lawn the Mrs.Bot has determined are offensive.
posted by iamabot at 11:02 AM on October 10, 2007 [1 favorite]

You might not have Bermuda. If you have big sturdy runners, that's likely Bermuda. You can plant within a couple of weeks of using the RoundUp, if you have to resort to that.

The preferred method is to cover the area you wish to degrass with either lasagna layers or heavy black plastic or both, for the entire winter. If you do go RoundUp, wait a couple of weeks before you cover, otherwise you can start today. In the spring you will have an earthworm party under the plastic and the soil should be fantastic and aerated and fertilized. You should yank up the dead Bermuda runners then, in case they are only sleeping.

On preview: what they said, and also pull up the runners.
posted by Lyn Never at 11:03 AM on October 10, 2007

caddis nails it. To be cheap, you can even use black garbage bags. Just make sure you weigh the tarp/garbage bag down with rocks so it doesn't blow away. If you just cut away the grass and leave bare dirt you will have the grass and a bunch of weeds appear over the winter. Solarizing the ground with the black plastic will kill all the grass and weeds while still providing nutrients for the soil in the form of decayed grass. Good luck! I love the look of thyme but I didn't solarize my grass - it is hard to kill grass inch by inch.
posted by saucysault at 11:08 AM on October 10, 2007

Per Lyn, RoundUp becomes inactive after a few weeks. I had to kill a nunch of stuff in my backyard before I could lay sod. After a month under tarps the damn stuff was still alive, so I used RoundUp. A week later, I put down my sod.
posted by GuyZero at 11:20 AM on October 10, 2007

If you are like me and you left piles of leaves in the yard you'll find that come spring, the grass is dead underneath only you would be doing it on purpose.
posted by mmascolino at 11:23 AM on October 10, 2007

I dug under my grass a few years ago and flipped it upside down in patches. When I came back to it in the spring, the grass had died and acted as a sort of compost for the soil (I assume; everything I planted afterwards came up very well).
posted by transient at 11:46 AM on October 10, 2007

I just wanted to thank you for posting this question - I had never heard of thyme as ground cover and now I know what I want in my yard in the future!!!
posted by agregoli at 11:51 AM on October 10, 2007 [1 favorite]

Sod cutter will work, but you might also try a rototiller. Fun to use and a good workout besides?
posted by psmealey at 12:00 PM on October 10, 2007

I used black plastic bags last year to kill some grass. I layered newspaper under it. Worked fine.
posted by konolia at 12:08 PM on October 10, 2007

Roundup only works when absorbed into the plants via the leaves. You can safely plant the new plants within a couple of weeks of using Roundup. However, being in the NE, it's probably too late this year if you have bermuda grass as it should be browning out for the winter already. Bermuda as a lawn in the NE would be sort of unusual though. It's more likely you have fescue.

I wouldn't wipe out the lawn this fall either way because you'll have a muddy mess all winter for a yard. Given the smallness of your yard, I'd get the soil tested by your local extension office, rototill in the spring and amend the soil as needed based on the test results, and plant the thyme.
posted by COD at 12:16 PM on October 10, 2007

Sod cutter will work, but you might also try a rototiller. Fun to use and a good workout besides?

Not good if the grass is rhizomous, in which case you end up with little bits that resprout again. It's OK if the grass has been thoroughly killed.

Whatever method you choose to kill your lawn, deejay, you will need to wait a couple of weeks, water your dead lawn patch, and then kill any re-sprouts. I have attempted to pull weeds out of many a groundcover "lawn" that was installed without this crucial step, and it was a nightmare.
posted by oneirodynia at 12:21 PM on October 10, 2007

Nitpick: the grass won't "strangle" the thyme, it will just grow through it. Which is annoying and unsightly, but they actually will live in harmony quite nicely, as far as the plants themselves are concerned.
posted by oneirodynia at 12:24 PM on October 10, 2007

I've replaced my whole back lawn with vegetables and herbs. Sheet mulching/composting did the trick for me. I like that it conveniently decayed in place, so there was nothing I had to dig up and dispose of afterwards.

Some instructions indicate that you can put down layers of newsprint instead of cardboard over the grass. It works, but not as well as the cardboard.
posted by sculpin at 1:01 PM on October 10, 2007

Round-Up and other herbicides would only be half-useful to us, because while it'd get rid of the grass, it'd also make it difficult for thyme to grow, no?
No. Roundup (well, the modern version of it, anyway) leaves no residual once the plant has absorbed it. You have to apply it when the plant is actively growing, though, or it will most likely wash away before being absorbed. You can plant other things a couple of weeks after spraying Round Up with no problems whatsoever.

If you are coming into winter and want the lawn to be gone by spring, you should leave it as is for now to avoid your backyard turning into something resembling a mud-wrestling rink without the bikinis and spray the grass at the first sign of it starting to grow again. Let it get as long as possible first, so there is more surface area on the grass to absorb the poison. Once the grass has died, till the soil to aerate it and put the dead grass under the soil where it will rot away nicely. If it is the kind of grass with rhizomes, you will probably need to spot-spray for a while to pick off the remaining survivors (the old rule is "one yea seeding, seven years weeding", but it shouldn't take that long). As long as your Thyme grows quickly and vigorously, it will win out over the grass, as grass needs huge amounts of sunlight to grow properly.
posted by dg at 8:11 PM on October 10, 2007

If you rototill or till at all, you will be bringing up lots of weed seeds that are currently dormant, and as soon as they get light and moisture, they will sprout. Your thyme will then have a very hard time competing with all your weeds.

Use the cardboard method, and make sure everything on top is weed-free (composted cow manure, wood chips, sawdust, weed-free compost, straw [NOT hay], etc.). In the spring, sow seeds thickly and keep moist. Unfortunately, thyme has a reputation for being hard to grow from seed -- my personal experience bears this out -- so you may want to start the seed in flats indoors in late winter and plant the plugs out in the spring.
posted by acridrabbit at 8:25 PM on October 10, 2007