Written by Jim Brazie, Sales Representative

The drought in California caused many traditional landscape irrigation systems to be converted to drip irrigation, reducing water usage. Drip systems, which adequately provide moisture to shallow rooted turf and shrubs, can also be designed to provide water for trees (which have deeper root systems).

Trees typically develop roots between 3 to 5 feet in depth and outward to the width of its canopy. This is referred to as the tree’s “drip line”. Mature trees need deep watering during the dry months of the year to promote healthy growth and resist diseases and pests. This deep watering is accomplished by using the same drip irrigation tubing used for the turf and shrubs. An individual drip line “ring” is installed at each tree in the landscape.

An individual riser from the underground PVC supply piping is installed approximately 18-24” away from the tree trunk.  A transition fitting allows for the drip tubing to be connected and laid out in continuous concentric rings out toward the “drip line” of the tree.

Tree's Drip Line

Spacing between the concentric rings can vary between 12 to 24 inches depending on the soil’s ability to absorb and hold water. The less absorption, the closer the space between the continuous drip tubing rings. The more the soil can hold water the farther apart the rings can be placed. Spacing between the emitters is also determined by the soil’s ability to hold water. Most drip irrigation manufacturers offer drip line with emitter placements in 12, 18 and 24 inch increments and individual emitter flow rates, nominally with flow rates of .5 and 1 gallon per hour. With multiple drip emitters per tree that surround the area inside the tree’s drip line, adequate amounts of water can be applied.

If possible, the irrigation system for the trees should be on a separate control valve and station on the irrigation controller. The valve station could then be operated for longer periods of time to provide the deep watering necessary for good tree health.

Your Hydro-Scape experts are here to assist you in irrigating your trees efficiently. Our knowledgeable staff can answer all your questions about drip irrigation and offer recommendations on the best products to achieve deep root watering for your trees.