Question: “Good Day, I live in Sparks and I have some questions about watering a couple of trees in my yard. The trees were put in seven to eight years ago. They are planted in DG so currently they are only watered by drip irrigation near the base of each trunk. I want to add irrigation rings placed out at the drip line of the trees. The tree’s drip rings are about 7 feet in diameter. Do I place the irrigation lines out at the drip ring right away or do I need to start closer to the tree and over time move it outward to the tree’s drip line? Thereby giving the roots a chance to grow outward. If i do need to start close and work my way outward. How long do I need to keep them in place before moving the irrigation rings? Thank you in advance for your assistance.”
This is a great question! Since the trees are seven to eight years old and have only ever received irrigation water at the base of the trunk (I’m assuming there is no irrigated turfgrass nearby), most of the root growth has likely been limited to a small area right around the base of the tree. You want to train the roots to grow outward by starting your first drip irrigation ring about 18 inches from the trunk and then another ring 18 inches out from that. This will provide irrigation almost to the drip line and should meet the irrigation needs of the tree for at least the next 2 years (depending on the species and how fast it grows). In a few years, add one more irrigation ring at or even a bit beyond the drip line. Make sure you are getting water down into the soil at least 18 inches to 24 inches every time you irrigate. Do this once per week (twice per week when temperatures get near 100 degrees). You can test your depth of irrigation with a soil probe after an irrigation cycle.
If it’s possible, remove or cap the emitters that are near the base of the tree, since there are few water-absorbing roots in that area and keeping the base of the tree moist could result in root or crown rot.
I hope that helps. Feel free to contact us again if you have further questions.
Heidi Kratsch, Horticulture Specialist at Washoe County Cooperative Extension