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Landscaping & Design/Concrete mixed with dirt


  I know this may sound weird but I volunteered to help my neighbor with a project and I need some advice.  She said she read someplace that if you mixed quickcrete with soil it would prevent grass from growing around her flower beds. I would imagine the basis for the idea is that you are basically making a weak concrete barrier (after a good watering).  She doesn't remember any of the instructions but wants to try it. I'll be doing about a 3-4 inch edge around her beds and I'm thinking it would be about 1 part quickcrete to 3 parts dirt.  I can't seem to find anything on the internet that even comes close to what I need so I though I'd check here.  Any ideas or points in a specific direction would be a big help!!

ANSWER: Hello:

It will also prevent her plants from growing. The high lime and salt content will kill any vegetation around the quickcrete.

The mix you are describing roughly resembles cement soil but this is made from clean soil (without clay) and portland cement. Cement soil does not contain an aggregate in the form of pebbles and does not contain sand, as quickrete concrete mix does.

You cannot mix soil into the quickrete without disturbing the mix ratio. The quickrete will not hold together and since it will not be hardened the salt and lime it contains will leach out into the surrounding soil.

If a border is all you want,just use regular concrete mix or stone or some type of masonry,plastic or wood.

Mark Harshman

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QUESTION: All she really wants to do is have a grass-less boarder around an already existing brick border. She feels that when they mow/edge the yard the grass clippings take root in her flower beds. I think your advice is right on about killing everything so my follow up is do you have any idea how much "leaching" I might expect?  This project is a definite go regardless so I'm thinking if I put a trench at the half way point between the existing brick border and how far out she wants to go the leaching will take care of the "kill zone" naturally.  

Keep in mind I'm just a hired hand gardening to me is cutting the grass lol so I'm taking the most logical approach I can think of.


I do not support poisoning the soil in any circumstances. There are other ways to do this then what you are proposing.

I have no idea about how much salt and lime poisoning will occur because I do not know the amount of concrete you are talking about and I do not know the size of the area but it takes very little salt to kill plants.  Applying concrete to the soil will leave a bare and unsightly area and as I said before will pose a threat to other plants.  This is not how herbicide is done. If the grass is not desired then replace it.

I do not see how leaching the soil with concrete dust will keep grass seed from blowing into the area. In my opinion such an action is destruction of property. A border will not stop blowing grass seed either. Applying mulch would be a better solution or hand weeding or perhaps a selective herbicide.

Grass clippings do not take root and while some grass seed may be spewed into the area while mowing,installing a patch of concrete dust will not help. A bag installed on the mower to catch the clippings would do more good.

Mark Harshman  

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Design of landscape structures and design of planting arrangements in the landscape. I usually do not answer questions of a horticultural nature or about growing plants or gardening unless they are related to design. I will answer these questions at my discretion. I will answer maintenance questions at my discretion,usually when they are related to design. I am a landscape designer. I am not a contractor or a gardener. Although I will describe how something is built I do not provide detailed installation or construction instructions. I do not recommend brand name products or services unless they are a clearly established practice. I do not recommend or give referrals to landscape related businesses. Here are example categories of problems I can help you with: Design of residential walks,low walls,low retaining walls,fences,drainage systems,arbors,plant selection,xeriscapes (low water use landscapes),rain garden design,rain water harvesting,permeable paving,sustainable drainage. No advise on an architectural or engineering level. I DO NOT PERFORM ACTUAL DESIGN WORK THROUGH THIS SITE. I only provide suggestions and advice. For more comprehensive help check out my website at:


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