A Landscape Architect friend of mine in the UK sells root barriers online among scads of other things. Ofer reminded me recently of something I had once taken huge care to deal with, back when I was working in the close confines of cities and suburban commercial projects. These projects were all just rife with restricted spaces and gardens over underground parking structures and they all found some relief with this new great product: Root Barriers. I recall using some of the very first large plastic and very strong root barriers in Monterey, California, in a new parking lot hard by the Monterey Aquarium. This was the first of what proved to be numerous applications of this handy and extremely effective material.
Root barriers are used to contain the spread of tree and shrub roots in order to protect other facets of a landscape from heaving and losing integrity. Easily-expandable large sheets of durable plastic now encircle the roots of trees up to 6 feet in depth, forcing the roots ever-downward in their search for water and feeding.
Root Barriers have only been developed formally since 1975. Obviously, efforts to control root growth have always been born closely in mind – all sorts of applications and efforts in the past have included concrete barriers/planters which we poured-in-place as well steel barriers and other efforts, typically always fighting the imperial instincts of expanding nature. It took the wonders of plastic to make this entire new field a more amenable and far easier task for installers and planners.
Yet, finding ways to combat something extraordinarily prevalent took more time than one might think. It has definitely been easy seeing the reasons for them. We all desired a product which could orient roots less invasive to the sides where the more obvious ravages appear and downwards to a “safer” a layer of soil:
We arrived at something like the above as a desired direction of root growth. We have since found that it is entirely possible to get there using the simplest of devices – a plastic panel, attachable to the next or simply rolled out and pre-measured – expandable and wrapped a reasonable distance around the tree or plant. Thus, not only does the barrier reduce the damage from expanding roots, it also has a lot to do with the emerging shape of the young tree above the ground. A result usually results giving a more columnar tree – at least until the tree’s roots expand and find what they need down below the barrier.
Modern structures have demanded even more attention to this detail as we continue to lay on the asphalt to “Paradise”, as Joni Mitchell so eloquently sang it, providing enormous parking facilities to accommodate our love affair with cars. Planting strips abounded in the later part of the 20th Century. In an effort to make these generally-abhorrent facilities more appealing to the eye, landscape designers decided a nice result would be to arrange thin planting beds between aisles. Demarking separate parking areas on the plane of a parking lot led to planting trees in abundance for various reasons – perhaps the most important of which is their thin profile near the parking spaces themselves which can hopefully better avoid bumpers and parking accidents. Shrubbery can fare poorly indeed in these situations. Let’s face it – this parking area is better than the one following:
Not too pretty, is it – the one below, I mean? Well, at least they don’t have to worry about maintenance! The below is what I like to refer to as a gardener-free Zone.
So root barriers allow us to implement a greener environment, sans the continual worries of upsetting the structure itself. Nor is it merely parking lots which are affected. There are abundant situations where reorienting roots to a lower water field are applicable. Retaining walls come foremost to mind, but any patio or residential or even general pedestrian thru-way applies here as well. Needless to say, roads, curbs and the various long term upsets of planting too closely to buildings and flat structures get some much needed relief, nearly no matter which trees are decided on. I have even seen Sequoia’s in the West treated this way to great effect, negating the inevitability of this, at least for a few years:
History: Once these controlling mechanisms became wider known, suddenly a raft of possible applications presented themselves. Suddenly bamboo could once again be specified for landscapes. Other ‘rhizoming’ plantings which are voracious and famous for it also became possibilities. It honestly did open up some real new and interesting possibilities. It’s truly amazing what a strip of plastic can do.
Plumbing: And not just plumbing, either, but all features of house supply of services, from water and waste to electrical and cable can now be protected by the insertion of such a simple and elegant solution at the face of these mechanisms, or just around the potential invaders. By directing the roots downwards, suddenly the invasions of Birch, Willow and other water-seeking suckers and trees becomes moot.
The benefits of root barriers are a relatively new technology. It’s a technology whose time has definitely come. Once again, my friend Ofer has a bit of information and a few interesting quotes in his website as well as a plethora of good and useful products. He designs and installs gardens and landscapes as well in the UK and is trying to get a bit of income for his growing brood over there in England Land. Here is his site, again, check him out:
Hi Steve, I found your post interesting because I have had a little experience with this product. I saw it in some little garden supply catalog several years ago and ordered some. We used what we needed then I forgot that had some leftover other than a scrap. This past spring I needed more. I searched current catalogs and Internet with no luck. I took the scrap with me as I went around town stopping at every store I thought might possibly have some. They all looked at me as if I were from outer space. They had never seen anything like it. Then low and behold (my project was on hold because of this), while looking for something else, I found one or two more new rolls of it in the garage. Hallelujah! But, then we ran into stone and tree roots, so couldn’t put it as deep as hoped. Anyway, we did the best we could. It certainly has opened up new possibilities for the industry.
Barbee, I think landscape suppliers are pretty reliable for these things. having said that, this is a new area, geographically, for me, so I am not sure.
I’m catching up on reading my favorite blogs, and I’m happy to report that even in my bitty plot there has been lovely fall color. Cotinus ‘Grace’ takes a starring role, but barberries and nandinas add to the mix.
Have a HAPPY TURKEY DAY!
Hey, thanks, Alice. Always so terrific to have you drop by. I confess, I have been busy as well – can’t wait to see your most recent posts.
It’s an important topic. When we planted trees here we made sure they wouldn’t turn the house upside down. And on a sidenote as your dedicated site admin – commentluv is now activated!
.-= IsraeliMom´s last blog ..Big Brother Israel – The Women =-.
As Robin Williams likes to say: “Spank you very much!” Or is that “mulch”? Thanks, Anne.
What a wonderful surprise! ,
you are The Man!
Me just looking to see what your blog is doing like and to see my name here.
I feel sorry for not yet sending you more photos of trees roots in Lawns.
You made my day!
LOL, Ofer. I am The Man, you are correct! Cool on making your day. I respect what you have done, dude. Keep up the good work!
I’ve used root barriers for golden bamboo, and seen a big mess when it was improperly installed for black bamboo. For trees, the studies I’ve seen seem to say the root barriers delay the invasion of roots into an area, rather than prevent it, and that folks should check with an arborist to see what effect it will have on the particular species they are planning to plant. My city (Richmond, CA) wants people to just pick a deep-rooted species instead.
Ryan, I agree completely on the long term solutions which root barriers only play a small role in. Obviously, over time, a Redwood, Sequoia, even a large, thirsty Birch tree will slap the paltry little root barrier around. I think the “solution” they offer is for a shorter term and that we can get an additional 10 years of non-invasive behavior over what would have occurred in, say parking lots or streets, where the massing of running water at those edges actually encourages lateral growth.
Bamboos are another story entirely. Some bamboos will evade restrictions and literally go over them, like rhizoming soldiers. The goldens tend to stay pretty focused for a long time. Once again, drip irrigation and other (inserted pipe) ways of watering can encourage deeper root formations with a bit of forward thinking. But, in the end, anyone expecting root barriers to be the bottom line is nuts. Choosing the rioght tree for “The Duration” requires more science.
Lots good info. I’m to young to know it was 1975 when they starting using root barriers. I was only 5 at the time. Thank you for the info!!!
It is a really amazing article to read and I got some amazing information about the root barriers technology.