Why corrugated plastic around planter box?

Motherdub

 

I refer to attach pictures. My garden is essentially a very large planter box on my balcony. I have this grey corrugated plastic around it but it's either full of weeds or dirt or both,and parts of it have collapsed. To tidy it up before I put a trailer load of mulch on it, I thought I would clear out the weeds and dirt from behind the plastic as best I could with a small trowel, and put stakes of wood up against it and hammer them in. I have a lot of pine skirting board in the garage that I thought I would use. Obviously the weeds will grow back but perhaps I can just squirt a tiny bit of weed killer up against the wall to deal with it. Just wanting to know know if I will damage anything by driving in wooden stakes close to that plastic. I wouldn't want to destroy some sort of membrane.

JacobZ

Hi @Motherdub,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

What you have found is corflute which is often used in landscaping to create a waterproof barrier between the soil and concrete structures. It's intended purpose is to direct water away from the base of the wall where there will be a crack between the blocks and the concrete footing that they sit on. 

You can see there is black bitumen paint on the wall, this is a waterproof membrane, so I'd suggest that the corflute is there to act as an additional measure.

Ultimately, if you are installing mulch, it is not really necessary to put stakes in to keep it in place. Simply stand it vertically against the wall when installing the mulch. Once installed, the weight of the mulch will hold it in place.

I'd suggest foregoing the stakes and simply stand the corflute up when the mulch is put in place.

Let me know if you have any further questions.

Jacob