Creating new beds out of grass lawns

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Permalink Reply by bonni on May 5, 2008 at 9:20am

Hi Kara,
I'm new to this site, but old to lawn gardening, so I can tell you with a certain amount of confidence that just slicing under the sod with a flat spade and peeling it up works fine (that's what we've done, and then composted the sod separately), but I suppose you can also turn it under on the spot and till it in for extra soil health.
I'm guessing that "two spade depth" is around 20 inches? That would seem like plenty for tomatoes. I've grown them in 12" raised beds for years.
My question for everyone else in on this same topic: My old woodsided raised beds are finally coming apart and I'm considering pouring a concrete perimeter for the garden (roughly 20 x 45). It's cheap, lasts forever, and -- important in our urban atmosphere -- tidy and easy to mow around. But before I go to the time and expense, I'm wondering if this is really a good idea. It seems like a good idea to me, but I just want to be sure there's not something that I'm missing.
Will the concrete adversely affect the ph? Will there be troublesome dehydration of the soil near the walls? Any input is much appreciated.

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Permalink Reply by Maya on May 6, 2008 at 6:46am

It depends on how you feel about paying for initial inputs. By far the best method if you don't have great soil under the sod in the first place is to cut the grass on your mower's lowest setting, then cover the (undug) lawn with good compost at least 12" deep. Rake it smooth, being sure to keep it that deep all the way to the edges of the bed. If your compost is truly good, this is a great method to use for slopes, as the compost holds its shape and does not erode. Let it sit for a couple of weeks to cool down, then you can plant directly in the compost. Having it that deep kills all the grass. Any that does eventually work its way up will be so weak from the struggle you can easily remove it. After a couple of months you can edge the garden. I wouldn't start out with root crops the first season, but it's fine for tomatoes. The roots and worms will break down the sod below over the course of time, making better soil below. By the second season you will be able to plant whatever you want. This is a method I've been using in landscaping and kitchen gardening for ten years now. I learned it from an organic landscape gardener who'd been doing it for at least 15 years before that. It works (and you don't have to pay the chiropracter nearly as much, thus offsetting any expense with the compost). If you have a good source of cow manure, use that. Do not use horse manure, as it contains too much weed seed because the hay and such are not ruminated and come through intact. Good luck!
Maya

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Permalink Reply by laura on May 8, 2008 at 7:49pm

There are no large dairys in my area but I was thinking maybe goat manure would work too. The goats are pastured so it would mean going out and collecting but I am willing to put the time in if its worth it. Any one ever use goat manure?

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Permalink Reply by Cat on May 6, 2008 at 9:47am

Hi Kara,

Our lawn is very similar to yours, so I know exactly what you mean by the hard work to manually remove the sod. But, in my experience, taking the time to remove the sod leads to a lot less weeds down the road. We just moved to a new house, and we want a full garden this season, so we're taking off the top layer of sod, chopping the soil below, then adding about 12" of compost and top soil on top in a raised bed form. I used the method mentioned by Maya in a small bed in North Carolina, and it worked great for tomatoes and basil (that's all I grew then), but I still got a lot of weeds, and I don't know if I could've done root crops or lettuces.

In response to Bonni's question, I would say that the biggest drawback to poured concrete would be the permanancy of the structure. It really would limit your options if you would like to move the garden, expand it, or when someone else buys your house. (I'm dealing with this sort of thing now in my new house). Have you considered cinder blocks? We've found piles of them free behind an old warehouse, and are planning to use them for a couple of our raised beds. I've heard that concrete can change the ph of the soil, but it isn't a huge concern if you are actively composting and amending your soil.

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Permalink Reply by Carla on May 12, 2008 at 4:45pm

Check out the book, "Food Not Lawns" if you can find a copy... it can be a little over the top and political for some, but has excellent advice on permaculture techniques. The author suggests a sheet composting method very similar to Maya's method for converting former lawn areas into food production- first lay down cardboard (scavenged boxes, etc) and wet it well... then cover with alternating layers of greens and browns- leaves, composted manure, well-rotted straw or hay (so as not to introduce weed seeds), kitchen scraps, newspaper, etc. Top with a layer of topsoil and/or finished screened compost, and plant directly in that... the materials underneath will break down and form rich loam for the roots to sink into. Great for urban areas where the topsoil isn't great, or to help alleviate concerns about polluted soil (though if this is a major concern, and soil tests have indicated dangerous levels of lead and other contaminants, it is best to seal off the soil with a 4-6" layer of well-packed clay). Much easier than double-digging, and easier on the existing soil structure and critters, and the cardboard and thick layer of compost materials will choke almost any grass before breaking down into the soil... however, ivy and other weeds with rhizomes may require more invasive/intensive techniques. If the ground is very compacted, it might be a good idea to aerate it and loosen a bit with a digging fork before layering the cardboard and other materials. I'm using this method to convert 10 bags or so of leaves that I've "rescued" from neighbors trashcans into a springy raised bed in our courtyard... I'm buying some topsoil/compost mix to make up the difference (it's a deep-cinderblock bed), but am happy with the results so far after several weeks! Good luck, and keep us posted!

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