I hear you on the depth—it really does seem to matter more than anything else. I went about 24” down with the ridged plastic and, knock on wood, haven’t had any roots sneak past in three years. The solid stuff just let them slide right along the edge, like you said. Digging up a section last spring, the ridges were still in good shape, no cracks or warping. Honestly, I think the ridges help, but if you don’t go deep enough those roots will always find a way. Maple roots are relentless...
I tried the solid plastic last summer, only went about 16” deep, and yeah—roots just slipped underneath like it wasn’t even there. I was hoping I could get away with less digging, but no dice. Might have to bite the bullet and redo it with ridged stuff and go deeper. Maple roots are no joke... they’ll find any weakness.
“Maple roots are no joke... they’ll find any weakness.”
Ain’t that the truth. I’ve seen maple roots bust through stuff I’d swear was bulletproof. Last year, I had a client who tried using that flexible corrugated plastic—looked sturdy enough, but those roots just laughed and kept going. Six months later, he’s got a mini forest popping up in his gravel path.
Did you use the smooth-walled stuff or the kind with ridges? I’ve noticed the smooth stuff seems easier for roots to slide along, almost like a slip-n-slide for them. The ridged barriers seem to trip them up a bit more, but only if you get deep enough. Sixteen inches sounds decent, but with maples... I dunno, I’ve had to go two feet down before I stopped seeing those sneaky little root tips poking through.
Ever try overlapping the barrier and then backfilling with gravel? I’ve heard mixed things about whether it helps, but in theory, it’s supposed to make it harder for roots to get a grip. Though honestly, sometimes it feels like they’re just waiting for you to turn your back before they make their move.
Curious—did you notice any difference in root behavior depending on how wet the soil was? In my experience, wetter spots seem to encourage roots to go deeper and spread wider. Maybe that’s just my luck.
Anyway, if you do end up digging deeper, watch out for those surprise rocks. Nothing like thinking you’re almost done and then hitting a boulder the size of a bowling ball halfway through your trench. Been there more times than I care to admit...
Maple roots really are relentless. I’ve had similar issues with the smooth-walled barriers—roots just seem to cruise right along them, especially if there’s any kind of seam or gap. The ridged stuff does slow them down a bit, but like you said, only if you get it deep enough. Two feet is about what I ended up doing after my first attempt at 18 inches failed miserably. Those roots found their way under and popped up in my patio cracks a year later.
I did try overlapping the barrier by about a foot and backfilling with crushed gravel (not pea gravel, but the angular kind). In theory, the sharp edges are supposed to discourage root growth, but honestly, I still found fine feeder roots weaving through after a couple seasons. Maybe it buys you some time, but it’s not foolproof.
About soil moisture—yeah, wetter areas definitely seem to encourage deeper root growth in my yard too. I’ve got a low spot near my fence line that stays damp most of the year, and that’s exactly where the roots went deepest. In drier sections, they spread out more horizontally just under the surface mulch. It’s almost like they know where the easy water is.
And those rocks... don’t get me started. Last summer I hit what I thought was just a small stone and it turned out to be half a buried concrete block from who-knows-when. Ended up having to reroute part of my barrier around it because there was no way I was digging that thing out solo.
If anyone’s still fighting this battle, my only real advice is: go deeper than you think you need to, overlap your barriers generously, and don’t skimp on quality material. Anything less and those maples will find their way through eventually.
I hear you on the maple roots—ran into a similar mess when I was helping with a sewer line replacement last fall. Those fine feeder roots will squeeze through just about any seam if there’s even the tiniest gap. From what I’ve seen, using thicker HDPE or reinforced concrete barriers (if you can manage the weight) seems to last longer than the standard plastic stuff. And yeah, depth is key, but also making sure your seams are sealed tight—some folks use construction adhesive or even metal flashing at overlaps for extra insurance. It’s a pain, but it beats having to dig everything up again in a couple years. Always worth double-checking for buried debris too... nothing like hitting unexpected concrete when you’re already knee-deep in mud.
