When irrigating a transplanted tree it is important to lay out the drip or dripperline in a manner that ensures that the plant can thrive in its new environment. To do this, make sure that the soil around the root ball and the native soil are adequately covered.

This may seem logical, but many contractors work with clients who only want to make sure that the tree gets through the first season. This often translates into a few drippers around the ball, or maybe only in the native soil with nothing around the ball. It doesn’t take long to find out that the customer said one thing to keep the cost down but really expected that the tree would grow and thrive.

When a tree with soil surrounding its rootball is planted into a different soil, water will not migrate from one soil to another. It is almost as if a moat exists blocking the water from its natural tendency to move laterally. As such, both types of soil must be covered with irrigation. This will ensure that when the tree’s roots reach into the native soil, adequate water awaits.

The easiest way to do this is to install rings of drip or dripperline around the tree, beginning with a few drippers on the ball itself. How far should you go? The correct answer should be to provide all of the tree’s water needs as a full-grown tree.

Root zones often follow the size of the canopy of the tree so that’s a good start. Work with your cooperative extension or arborist for more information. Once you know the “estimated mature drip edge,” extending the irrigation lines out is easy, and the tree will not rob water from surrounding plants or turf.

All of this becomes more challenging when irrigating street trees. Here, it is common to place a grate around the trunk along with a bubbler or two, while the rest of the soil is covered with pavers or concrete. But with dripperline you can design a layout of rings under the pavement surface that will provide water to the roots, just as we did above. Who knows, you may have the first street trees that actually look good. 

 

Editor's Note: Mike Stoll is marketing manager for the landscape division of Netafim.