Proper Installation of Root Barriers

When to Install

• Root barriers should be planted when the tree, shrub or plant is first planted or very young. If you wait, you run the risk of damaging the roots and, subsequently, the tree or plant. When you install a root barrier at the initial planting, be sure to dig your hole wide enough to accommodate the plant's natural root spread.

Where to Install

• If you install the root barrier after the tree or plant has matured, you'll need to ensure that you're not cutting into important roots. You can usually tell by looking at how far out your branches spread. This should be about how far out your roots spread. With new plantings, install the root barrier about as far away from the plant as the foliage spreads. Consult with a local nursery before installing a root barrier. In some cases, the roots will simply grow deeper, but not always. Every type of tree, shrub or plant is different.

What to Install

• Root barriers come in a variety of materials. Those made of concrete, metal or plastic will last indefinitely, though they'll be susceptible to the freeze-thaw cycle, especially if the barrier is above the frost line. Chemical barriers last about five years. The chemical comes from pellets affixed to a fabric. There have been recent advancements in chemical barriers, including Biobarrier. It's made of a durable polypropylene fabric that leeches the root-inhibiting chemical and blocks roots, yet allows air, nutrients and water through.

How to Install

• To block the spread of tree roots, you'll need to set the root barrier 30 to 36 inches deep. Plants and shrubs with invasive roots require a barrier that's 12 to 18 inches deep. Digging a 3-foot deep trench around an established tree isn't easy. Neither is digging a 12-inch deep trench. If it's a mature tree, you'll need to leave time to dig the trench. Try to dig when rain isn't in the forecast. When installing, make sure the barrier is upright in the trench and that there aren't gaps in the barrier for roots to grow through. A fabric barrier will lie against on side of the trench. Fill in the trench and tamp down the dirt when finished. If you're installing a root barrier when you first plant, it may be as simple as making the hole wider in circumference. If it's a large tree, you may have to dig a trench further away from the planting area to allow for adequate growth. Again, check with a local nursery about the specific needs of your tree, shrub or plant.