How do I apply bark as a weed killer-do I need a membrane underneath?

Question

How do I apply bark as a weed killer-do I need a membrane underneath?

Answer 1

Yeah, you definitely need something underneath.  Weeds don't have a problem growing up through even thick layers of bark.

You can use landscaping fabric, or thick layers of newspaper or cardboard, or (if this isn't a garden bed, but a path or an area where you want nothing growing) even old carpet scraps.  The advantage to newspaper or cardboard is that if something does manage to make its way up through it, you can dig it out without pulling up a huge expanse of membrane in the process, which makes quite a mess. The advantage to carpet is also its disadvantage: that stuff will *never* break down.  So, it's not very organic, but it'll be there for a good long time.

Whatever you use, you'll have to replenish the mulch from time to time, since it does decay into soil over time.

Answer 2

Bark cannot be used as a weed killer but it is very effective at suppressing weeds.  By covering the ground in bark it stops light getting to the soil and therefore hinders the growth of weeds.  I use bark all over my garden, it's great cos it looks really attractive and your plants really stand out against it.  About the membrane.  You can use a membrane before putting the bark down.  The membrane stops weeds growing through but the only problem is that when you want to plant something at a later date you have to cut a hole in the membrane in order to dig a hole for your new plant.  This doesn't sound like much but believe me, when you've got a few plants to plant and you have to start pushing the bark to one side and then cutting the membrane it really is a pain in the backside.  I know from personal experience.  If I were you I would just use the bark on its own but make sure you cover the earth with a thick layer of bark.  It can work out very expensive as a bag of bark really doesn't cover much ground at all and despite looking very hard I haven't found anywhere that sells bark in large quantities - you can only buy it in bags from garden centres and places like B&Q.

Good Luck!

Answer 3

I put down a barrier an then the bark, looks great.

Answer 4

easier if you have a membrane as then you are excluding light from the weeds spread a fairly thick layer of bark to make it look effective

Answer 5

put membrain down it stops weeds then put bark on any seeds that germanate wont be ablr to put roots down so will be pulled out easily

Answer 6

You should have the weeds out of there first.  Then a covering at least 4 inches thick, better 6 inches will help r****d, not prevent, future weed growth.  

If you use a membrane, also have the weeds gone.  Use a semipermeable membrane, actually a weed barrier fabric, and you can get by with 3-4 inches bark.  Anything less and it shifts around exposing the fabric.  Over lap the fabric edges very generously and use the pins to secure to the ground.  Remember dirt can still blow onto the fabric over time and provide a medium for future weed growth on top.

The bark works by preventing light from reaching the germinating weeds down at soil level.  If you have a lot of walking across the bark, or Rover likes to dig, light will get down and allow weeds to spring up.  At least with a 6" mulch any weeds that do reach the surface are pretty weak and can be pulled easily.

Personally I prefer to use the weed barrier fabric underneath instead of relying on mulch depth.