Concrete mulch.

October 24, 2009 1:54 PM

Is using a concrete slab with holes for plantings the best weed prevention in my backyard garden?

My backyard has turned into a jungle of weeds and tree saplings and I want to make it civilized again. An area about 10'x30' needs to be tamed. I garden in Boston. I want to plant butterfly bushes in that space. Mulch, weed barrier fabric and constant weeding don't really work. I thought a concrete patio with round openings formed into it would minimize weeding. Any suggestion for other material that would be as effective?

posted by boby to home & garden (14 answers total)

Some weeds will break through concrete eventually, and then you'll really be in a mess. Until that point, it will be effective, though.

The problem is going to be clearing out the weeds before laying the concrete. If you can do that thoroughly, you'll be well away, especially if you plant the bushes in tubs. If you have tree saplings, though, this is going to a big big job.

Get some goats in to eat everything. And then some pigs to dig the roots up. It sounds unconventional, but it works. A bit more info. They'll take out all of the greenery quite effectively, leaving you free to lay your concrete on the sub base.
posted by Solomon at 2:35 PM on October 24, 2009

Well, yes, pouring a concrete slab will certainly minimize weeding, but it may not be the best approach. In addition to concrete work being expensive, it may be something that requires permits and such in your area and it creates a pretty permanent patio in what is currently green yard.

My best advice is to talk to some gardeners who know your area and its environment well -- not the people at Home Depot or whatever. There is probably a good variety of low-growing native or well adapted plants you could use w/ the butterfly bushes that will outcompete most weeds. My best experiences (in Texas, so YMMV of course) have involved playing around with combinations of tough, drought-resistant natives and some decomposed granite paths (which provide excellent weed blockage here).

I too hate to weed....
posted by pantarei70 at 2:35 PM on October 24, 2009

Do you, by any chance, have something like Japanese knotweed back there? I've done a lot of yard- and vacant lot-reclaiming (I worked for a community gardening nonprofit), and a combination of mulch and some kind of barrier handles almost anything. We would just lay down overlapping, wet cardboard boxes beneath 6-8 inches of wood chip mulch, and it worked like a charm.

Also, concrete is one of the most garden-preventing-est, hardest to remove, most irritating things to find in a spot where you want to put a garden, and in Boston, you'll need to put a few inches of gravel beneath it and run rebar/reinforcing wire through it to keep it from cracking up. You'll almost literally be setting your garden layout in stone, and it will be a headache if you ever want something different, or of the next occupant of your house wants something different.

Oh, and of you do have Japanese knotweed, concrete is probably a good option, but get ready for the fight of your life. If your patio ever does crack, it'll just shoulder its way right up through it.
posted by pullayup at 2:43 PM on October 24, 2009

You might check out the Master Urban Gardener program (MUG). They train volunteers to provide advice to urban gardeners like yourself.
posted by JackFlash at 2:45 PM on October 24, 2009

No.
posted by torquemaniac at 3:02 PM on October 24, 2009

We had weeds having weeds in grass that we wanted to convert to a flower bed. We covered over it with black plastic garbage bags, weighted it down, and let a full summer of sun and heat burn them. The following year, we dug, planted, and put a good couple of inches of fine bark mulch on the soil, pulling baby weeds asap if they dared come up. So far, it's worked. I'm in Toronto, so I imagine the zone is a bit colder than yours. BTW, this won't work if the weeds you have spread by runners. The only thing that worked for me when my mum's yard was invaded was to dig a trench, put in a 1' plastic barrier, cover the soil with black plastic garbage bags, then mulch over. Even then, some of the runners managed to make it 6+' to the nearest clear spot.
posted by x46 at 3:03 PM on October 24, 2009

I've heard good things about Lee Reich (lives and farms in the Hudson Valley), and his book Weedless Gardening. Might be worth seeing if the library has a copy... I believe his approach uses a combination of lots (lots!) of compost & mulch, similar to sheet mulching.

Just out of curiousity - what kind of weeds are you up against?
posted by pilibeen at 3:20 PM on October 24, 2009

Maple seedlings, morning glory vines, dandelions and others.
posted by boby at 4:33 PM on October 24, 2009

Dude, just weed. I live in Boston, I garden in Boston; paving over a 10'x30' yard to get rid of maple seedlings is ridiculous.

A couple of hours every other week is more than enough time to manage it. Plant some groundcovers under the buddleias, mulch if you want, and every time you swing by the yard pull out a couple of weeds. It's not worth the expense, trouble, and - frankly - the ugliness, of paving over your yard.
posted by lydhre at 5:31 PM on October 24, 2009

How much will all of the work to tear up your back yard and pour the concrete cost, including the hours of labor? Compare that with the cost of hiring someone to come out to your yard once a month during the growing season and weed for a couple of hours. If you have neighbors with kids, it may take 10-20 years before the concrete ends up being cheaper, and you can have a nice yard in the process.
posted by markblasco at 5:42 PM on October 24, 2009

Like markblasco says, I think you may be drastically underestimating the cost of concrete done right. If you're wanting to use it as a patio, I'd assume you want it to last beyond one winter. For this, you'll need to dig below the frost line in your area, pour gravel, then pour concrete. You're looking at several thousand dollars at least.
posted by odinsdream at 5:49 PM on October 24, 2009

Please consider the other impacts of paving over your green space. [1], [2], [3], etc.
posted by serazin at 6:16 PM on October 24, 2009

seconding pullayup's suggestion: flatten & layout out cardboard boxes so they overlap - cover with wood chips

this is the way a local farmer i know prepares new areas for planting: cut trees & bushes, pull up major roots & remove - then cut the grass & weeds to leave as primary mulch & cover with cardboard & secondary mulch - leave to overwinter

in the spring when you want to plant, simply cut a small hole with a sharp spade or trowel - very little weeding necessary - and the mulching process makes for a rich soil
posted by jammy at 5:38 AM on October 25, 2009

Concrete is a long term solution but I'll still be looking for a less expensive easily reversible weed barrier. Thanks for all the input.
posted by boby at 3:17 PM on October 25, 2009