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I have a very uneven back yard, from a combination of settling, bad maintenance, and a very enthusiastic dog (digger) that a previous owner kept out there. As part of a large backyard landscaping project, we will be flattening this lawn and growing clover instead of grass.

My current plan is to fill in the low spots and spread a couple inches of soil over the whole area (~75' x 35'). I'll cut the grass as low as I can, but will there be problems from leaving the root systems in place? I've considered renting a tiller or power rake, but I'm worried about destroying a rented tiller, and I'm not sure how deep a power rake is going to get. There are plenty of mid-sized rocks and hidden concrete pavers out there.

Update: my big concern is what will happen to the soil itself with a layer of dead grass underneath. I'm not as concerned with some grass growing up through the new top layer.

ench
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  • Are there any trees? Trees don't respond well to changing the grade/height of the soil above their roots because it cuts off oxygen. – Philip Apr 13 '16 at 17:57
  • Three fruit trees, and I'll be minimizing the soil added over their roots. Two are recent and haven't extended their roots very far, and the established one is in a higher corner. – ench Apr 13 '16 at 17:59
  • This is not a duplicate to your proposed procedure, but it might point you at a method that could be easier, with similar results (in your case, "add clover seed" would be an additional step with each soil addition, and you could go a bit deeper) http://gardening.stackexchange.com/questions/17992/how-should-i-fill-and-reseed-shallow-depressions-in-my-lawn/17996#17996 – Ecnerwal Apr 15 '16 at 02:21

1 Answers1

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Depending on the grass (certainly with kikuyu), it will break through the additional soil very quickly (I made this mistake recently).

You might consider spraying the grass with glyphosate [ie the active ingredient in most common weed killers - often called "Roundup" ] first - although this could harm the trees if significant quantities get onto the leaves - so try and do this on a sunny, windless morning, and keep the spray low to the ground. (Theoretically roundup becomes inactive on contact with the soil and doesn't affect the roots, there are arguments arround that it leaves residue - which are denied by most companies). NOTE: Do not cut the grass before spraying, and note that it can take 2-3 weeks for the grass to die.

davidgo
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  • Not an unreasonable idea. I'm not worried about a perfect lawn, as long as the clover has a head start. I'm going to avoid using any pesticides though, just not my speed. – ench Apr 13 '16 at 21:55
  • Would it be practical to cover the lawn with black plastic sheeting for a while? In that case, maybe you could cut the lawn short, then cover it with plastic for a few weeks to deprive the lawn of water and light, and depending on where you are heat it to suffocate whats there and give the clover a decent head start when you add the new layer of soil ? – davidgo Apr 13 '16 at 22:02
  • (I also came across http://www.geeksongardens.com/way_5642923_easy-way-kill-grass.html - this talks about using vinegar - I think glyphosate is probably better and less toxic to your garden, but mention it in case your beef is with synthetic herbicides.) – davidgo Apr 13 '16 at 22:06
  • I'm more concerned with the breakdown of the organic material than grass growing through. If the old grass roots are going to break down and leave depressions in the new lawn level. – ench Apr 13 '16 at 22:12
  • The roots of dead grass will shrivel up and become compost. What about glyphosate, wait a few weeks, then use a lawn roller or plate compactor to compact the substrate before putting down your clover ? – davidgo Apr 13 '16 at 22:17