Best material for in-ground divider (to contain suckering)

I'm getting ready to move my raspberries and blackberries to their new home after potting up and moving from our old property. They will be in a fenced garden area here and I'll need to contain their roots (I will have more wild ones in the food forest and I already have native ones for foraging, but I want a contained grouping in the perennial border of my annual row garden area as well). I'm looking at corrugated roofing options since I can get them in the right length and width to make my 2ft deep, 6ft long sections. I know people use the galvanized metal roofing to make raised beds, which would be a similar application, although all but the top 6-8" of my 'walls' will have soil on both sides instead of just one. I'm concerned about longevity and wondering if the PVC panels would hold up longer in that application. I'm generally trying to stick with natural materials everywhere, but for this particular application, I need something that WON'T break down in an environment that excels in breaking things down. I can't have raspberry canes popping up in my pathways and annual veggies.

Thoughts?

I have been looking at trying those cheap roll up sled sheets.  A tough plastic in fairly long lengths that specials fairly cheaply late winter season usually.  Bury and then lay a board edge over the top to protect the top of the plastic from the sun.   For raspberries might even be able to split down the middle as raspberry roots don't seem to go real deep.  So a 28 inch wide sled might split in to 2 14 inch wide strips.

I think you’ll want to look for materials truly designed to survive outside in soil in all kinds of weather. Something like materials used for pond liners, maybe, or outdoor water tanks.

Many kinds of plastic, for example, get brittle in cold weather and could crack and defeat the purpose. But other kinds that are designed for the purpose and are durable in all weather.

Mk Neal wrote:I think you’ll want to look for materials truly designed to survive outside in soil in all kinds of weather. Something like materials used for pond liners, maybe, or outdoor water tanks.

Many kinds of plastic, for example, get brittle in cold weather and could crack and defeat the purpose. But other kinds that are designed for the purpose and are durable in all weather.

Good point about becoming brittle in the cold. I was thinking something rigid/solid because I worry about roots being able to break through thinner materials. I had laid a double layer of a heavy duty tarp under a pile of fencing panels last year to stop plants from growing up through the fencing panels until I was able to get them installed but I still found 2 of the panels pinned down to the ground because a black locust seedling pierced through the tarp like it was nothing.

Plastic drums cut into 2ft rings would probably work, but I'd need a lot of them to span length of the bed and lining up circles would result in a lot of unusable space. I don't have access to outdoor water tanks, but I could have access to IBC totes which might be ideal except that I planned for my perimeter beds to be 30 inches wide (and 6 foot long before dropping to the next terrace) and IBCs are 40 inches wide x 4 foot long.

In a previous thread ceramic tile was suggested as a permanent barrier. It has a lot of appealing properties: it's inert, not going to corrode, (hopefully) not going to leach anything bad into the soil, nice and strong, and can be collected free from surplus material. I made a raspberry bed using 12" tall tiles (pics in the other thread) and it has been working great. It sounds like you're looking for something slightly taller. Bigger tiles might be a little harder to source, but they exist. A lot of modern bathrooms and commercial facilities are going with large (18"x36" or something like that?) tiles, so if you could source some discards from a project like that, you might be in business.

I mentioned in the other thread that something I had been using as a temporary solution was corrugated plastic like what's used in political yard signs. Plenty of that around to be discarded after an election. I've had a piece in the ground for something like 4 years and it is holding up just fine. A little bit of degradation along the top where it's exposed to the sun, but the stuff under the soil surface seems totally intact.