Irrigation Options
Dripperlines for Large Shrubs and Trees
Garden Tip
Technical Bulletin Series
Providing optimum water distribution for large shrubs and trees is one of the most essential planning and maintenance practices that can be made.
On mature large shrubs and trees the roots very near to the trunk are larger diameter roots that do not take up water and nutrients. Instead these feeder roots are located 2 feet or more away from the trunk. Smaller roots are capable of absorbing water and nutrients which are then translocated into the plant.
Often however, there is not adequate room for applying water to larger plants, so we try to make the best of what is practical.
  Here a tree is planted within a reasonably small planting circle. This is often the case where the tree is surrounded by concrete or asphalt driving or parking areas, and is provided a small contained growing area. In this example a "Double-Ring" dripperline has been installed to help distribute water throughout the first 3 or 4 feet of root area. An additional ring would be recommended when the tree (or shrub) has been established for more than a year in order to help the roots expand.
Another technique for installing dripperline is to lay it out in a spiral like this.
 Spirals are much easier to assemble, as there are no cuts and connections to be made. They also can be laid-out in virtually the same way as concentric circles.

 This example shows 1 foot spacing between each row. This is usually appropriate for larger shrubs and trees. If installing dripperline for a smaller shrub (say; 3 to 4 feet in diameter), the spacings would be closer, perhaps 6 inches.

 In hard-clay soil, the moisture will easily spread 12 inches, and an even distribution can be attained. In sandy or porous soil, moisture won't spread as far, and the distance between rows will need to be reduced.

Here is another example of a spiral shaped dripperline
being used to water a small tree and some surrounding flowers.

Depending on Soil Composition
Either of these two options can help
Secure the dripperline in place

However you choose to design your Dripperline
or other Drip-emitter layout,
the objective is to provide good distribution of water.

Details for 12 inch spacing Dripperline
¼ and ½ inch diameters

Knowing the total gallons being provided and the square foot area under the tree or shrub can quickly tell you if your irrigation design is going to provide enough water for the plant in question. The Garden Calculator Pro-I is designed to help you know!