Landscape Rock + Black Plastic Weed liner = BAD CHOICE   5 comments

I moved to Minnesota in 1999 and I noticed that most houses did this rock mulch thing…  I get it…. cuts down on weeds, gives a clean appearance and doesn’t need refreshing  like  wood mulches.

But, I have to say, my tune  has TOTALLY changed.

Yes, it’s generally effective for keeping weeds at bay, but it requires tons and tons of rock and it’s not foolproof.  The weeds will get thru the spots where the landscape staples pierce the black plastic.  But beyond that, it’s terrible.

So what happens if you want to plant something?  First, understand that soil is alive.  But when you put plastic over it, and cover that with 50 lbs of rock on a square foot of ground, you’re smothering the ground.  No oxygen, no moisture = NO LIFE.  So, 3 years after you put down the plastic, don’t be surprised when you find no earthworms or other bugs cuz they can’t live there either.  So, what makes you think a shrub or perennial would want to live there?  You want to cut a hole the size of the pot the plant came in so you minimize the amount of non-plastic area to minimize weeds.  Well, guess what?  Only that area is going to get oxygen and moisture.  The roots are not going to want to expand past the width of the hole.  The weeds and grass are going to rush to that hole and now your plant is going to have MORE than its fair share of weeds!

Now, I’m going to stop preaching and give you a REAL LIFE example from my OWN experience:

The daylily story.
2 years ago, I planted 6 daylilies (Rosy Returns) in that terrible rock mulch that the previous owners put ALL THE WAY around the house.  I figured they could handle it.  Well, even THEY hated being planted there.

I noticed very little growth from them in the last 2 years and when I pulled them out, I could see why.  I could see that the hole I cut for them into the black plastic weed barrier was only about the width of a 1 gallon pot.  So, there was nowhere for new growth to go.  When I dug them up, I could see new fans trying to pop thru, but couldn’t.  The roots hadn’t wandered much past the width of the cut plastic.

What floored me was the extent of the grass infestation.  The bluegrass/quackgrass had traveled 12 inches from the lawn to get thru to the daylily holes.  And there were sections of grass that were nearly as big as the daylily.  Pulling this grass was pointless… the roots were NOT coming up!

So, when I took out the daylilies, I washed most of the soil off so I could see where the grass roots were and get them removed.  There were some grass roots that were encircling the plants and nearly choking the daylily roots. Some of those roots were almost as thick as drinking straws.

My goodness, that was a lot of work for those little plants!  But, now I can see that if I intend to plant anything in the areas where the previous owner loaded tons and tons of limestone on top of  2 layers of black plastic, I am going to have to remove all of that junk to allow the soil to breath and re-acclimate to LIFE!


Posted May 15, 2010 by koskashostas in Garden Design, Other Perennials, Shrubs, Weeds

5 responses to “Landscape Rock + Black Plastic Weed liner = BAD CHOICE

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  1. Just want to say what a great blog you got here!
    I’ve been around for quite a lot of time, but finally decided to show my appreciation of your work!

    Thumbs up, and keep it going!


  2. Pingback: It’s about time! «

  3. Go my site and start reading about the soil, I offer that you will find that there is nothing you can do about the soil!

    If you add organic matter to the surface of the soil the soil organisms will change the soil.

    Yes, I know we want to and think we can change the soil but we can not.

    As to the soil sample, it doesn’t matter and only matters to farmers growing seed crops on an annual basis not for perennial beds.

    If you like I’ll explain any of the detail if you study a bit on your part and come with questions based on I don’t get this or that,

    • Hi Butch…
      I’ve poked around your site a bit and even commented about rooting hostas in water. I guess my thoughts on testing the soil in this new bed is that since it’s not seen the light of day for a while, it might be prudent to get it tested and at least find out about the NPK anyway. There’s no earthworm activity in this bed, so I already know it’s deficient in organic matter. So either way, it’s getting organic matter. It might even get some black dirt come spring. Thanks for your comments Butch! Happy Hosta-ing!

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