My elderly neighbor has a parking strip that is infested with goat head weeds. With my neighbor's permission, I'm planning on ripping out the weeds and replacing with weed cloth and mulch. To prevent needing to do this again in the near future, I'd prefer to sterilize the ground before laying the mulch.

The parking strip is on a hill that drains into a major road. I'm not at all concerned about the runoff damaging plants we want to keep, and my first inclination is to salt the ground.

How much salt/foot of parking strip will do the trick? Alternatively, are there any better ways of accomplishing the goal of sterilizing this soil?

Again, this is all with the consent of the homeowner, who would have preferred that the city just paved the strip in the first place. :-)

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    From your spelling you sound like you're in the US. You could still use sodium chlorate which is pretty effective – Chris H Sep 4 '17 at 8:28
  • "The parking strip is on a hill that drains into a major road. I'm not at all concerned about the runoff damaging plants we want to keep" - but you SHOULD be concerned about where the stuff goes once it hits that road and drains into a water body somewhere. – That Idiot Oct 10 '17 at 19:31

Why not just leave the wildflowers be? - Spray and Geotex / weed cloth / weed barrier just encourage brambles, bindweed, etc. and destroy natural diversity (in other words you will find yourself in a losing fight against some very hardy, most near-irradicable, plants), whilst salt will run-off into other areas when it rains (desroying the arability of those areas, too).

  • I agree with this sentiment. There are lots of native grasses that could also fit the bill. OR, for all out "sterilization," cover the area with flagstone. – That Idiot Oct 10 '17 at 19:32

Here are a few of my thoughts. The salt under fabric isn't going to help your cause. If you put mulch on top of fabric, within a year, that mulch will turn to compost aka a perfect place for weed seed germination. The fabric if done properly would prevent weed seeds from within the soil from getting through, therefore the salt would be unnecessary in that case anyway. I NEVER encourage people to use fabric with mulch. The only time fabric is acceptable in my opinion is if you are putting gravel or river stone down, and even then it's never going to completely eliminate your weed problem.

So here are some options

  1. If you chose to/already have put fabric down with mulch on top, then you will want to re-mulch that area probably every year forever or the weeds will come back with a vengeance. No need to salt the earth prior

  2. If you really want mulch and not gravel, then either manually remove weeds, or use a chemical to kill them (only if manual removal is unreasonable). Then put a thick layer of mulch on top along with annual or biannual reapplication.

  3. This is what I would do. Use a string trimmer to cut the weeds down to the ground. Lay a good quality landscape fabric for use under gravel. Put gravel on top, a nice thick layer, 3-4" (tan pea gravel is my favorite by far). Since gravel doesn't turn to humus, it will be much better at discouraging weed growth long term, however the weeds will always find a way. Your first line of defense is to blow off any leaves, soil, mulch or any organic matter that tries to settle into the gravel. My favorite tool by far for managing gravel driveways is a flame weeder. Basically, it's a more mellow flame thrower that you can purchase very inexpensively. When weeds show up, you burn them down. It's quick, easy, fun, cheaper than chemicals and also nontoxic. It kills existing weeds and can also discourage future growth by destroying dormant seeds near the surface. I find that flame weeding driveways only needs to happen about 2 to 3 times per growing season here in NC to keep your driveway weed free. Boom.

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