The roots of the Rowan tree (also known as Mountain Ash) have a bit of a reputation for being aggressive. Their growth is so vigorous and dense that they can actually damage underground pipes and utility lines. Because of this, installing a root barrier is a smart move if you’re planning to add one to your landscape.
What to Keep in Mind When Planting
During its first few years, a Rowan tree’s roots grow surprisingly fast. Before you know it, you’ve got a thick, tangled root system that isn’t exactly easy to keep in check. These trees are shallow-rooted, meaning the roots spread out horizontally just beneath the surface rather than diving deep into the earth. Between the larger main roots, a felt-like mat of smaller feeder roots develops. The good news? As the tree matures, that frantic root growth eventually starts to slow down.
If you’re thinking about planting a Rowan in your garden, you’ll want to give it plenty of breathing room. Stay well away from pipes, lines, fences, and other plants. If the tree is too close, that intense root pressure can cause real structural damage. I highly recommend installing a root barrier that goes at least 30 inches (80 cm) deep into the soil.
Try to keep the barrier at least 5 feet (150 cm) away from the trunk. Just keep in mind that when you use a root barrier, you’re limiting the tree’s ability to “forage” for its own food and water. This means you’ll need to be a bit more diligent with watering and fertilizing. Adding a nice layer of mulch around the base is also a great idea—it helps the soil hold onto moisture much longer.
Keep an Eye Out for Root Suckers and Seedlings
Rowan trees love to send up numerous “suckers” or seedlings from their roots and around the base of the trunk. It’s the tree’s way of ensuring its survival, but for us gardeners, it can become a headache pretty quickly. If left unchecked, the tree can easily take over an entire flower bed, leaving little room for your other plants to thrive.
To keep things tidy, make sure to prune away these side shoots regularly. Once a Rowan tree is established and large, removing it along with its entire root system is a massive chore. That’s why it’s so important to pick the perfect spot from the start. If you ever need to transplant one, do it while the tree is still very young!
