Watering With Drip Irrigation

Landscaping that is not flat, areas that have mounds or berms designed into them, are perfect locations for drip irrigations systems. The use of traditional watering methods in these areas provide for extensive water run off, before the water is actually absorbed into the soil where it is needed. With the inherent low flow rates of drip irrigation, water is delivered to the soil before it has a chance to run off the area.

Table 1 provides the advantages and disadvantages to drip irrigation. After all, nothing is perfect.

Table 1 - Pros & Cons of Drip Irrigation
Pros	Cons
Reduced run off - water is delivered at a low flow rate directly to the soil.	Requires some planning and thought with respect to placement and quantity of emitters and nozzles.
Can be installed for above or below ground watering.	Little water actually appears around the plant or on the soil making it difficult, at times, to determine if the plants are receiving sufficient quantities of moisture. The addition of visual water flow indicators to the drip irrigation system provide a solution to this situation.
No overspray - avoids siding staining and discoloration of decks, fences, retaining walls, patio stones and driveways.	Older style emitters and nozzles require periodic cleaning especially in areas where the water contains heavy concentrations of minerals. Newer systems contain filters to remove minerals and nozzles and emitters that self-clean and are less likely to become clogged.
Easily changes with changes to landscaping and gardens - emitters and nozzles are easy to add, delete and change position, when the plantings in the garden are adjusted.	Tubing that is above ground can be unintentionally damaged if it is not held down with wire anchors and covered with mulch or a thin layer of soil.
Convenient watering for window boxes, planters and containers.	Tubing is easily damaged while performing plantings or other gardening projects.

Drip Irrigation Nozzle & Emitter Placement

Having the correct proportions of air and water in the soil will determine whether the plants are healthy and will grow efficiently. Because of this, the drip irrigation system must be configured for the moisture requirements of the plant based on its size and the length of time that it has been planted.

Nozzles should be placed directly over the root ball with all new plantings or trans-plantings.
When dealing with plants that have continuous growth such as trees and shrubs, emitters and nozzles will have to be relocated and added as they develop over the years. With perennial plants nozzles and emitters usually remain as installed for the life of the plant.
You must know the water requirement of each of the plants, trees and shrubs in your garden and landscaping. Larger plants have a larger root system and hence, generally require more water which means more nozzles and emitters. Whereas smaller plants will require less water and plants such as cactus even less.

Table 2 provides a guideline for the placement of nozzles and emitters based on the type of soil.

Table 2 - Nozzle & Emitter Placement Based On Soil Considerations
	Clay	Loam	Sand
Separation between nozzle and/or emitters	24"	18"	12"

Table 3 can be used as a guideline for determining the number of emitters or nozzles and the number of gallons per hour of water that should be delivered to the plant, tree or shrub. It is always wise to find out the specific water requirements of each species of plant, tree and shrub from your local nursery.

Table 3 - Emitter & Nozzle Quantity Guideline
Plant Type	Gallons Per Hour	Quantity Of Emitter/Nozzles		Comments
Plant Type	Gallons Per Hour	Loam & Clay	Sandy	Comments
Perennials	1	2	3
Trees (less than 15’)	2	2	3	12” to 18” from the base of the trunk.
Trees (15’ – 25’)	4	2	3	24” to 30” from the base of the trunk
Trees 25’+	Drip irrigation is inappropriate for a tree this large.
Shrubs 1’ – 5’	2	2	3
Shrubs 5’+	3	3	4
Willow	1	2	3
New Tree Planting	6	3	4	1” diameter trunk
New Tree Planting	12	3	4	2” diameter trunk

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