Standardizing Your

Irrigation Emitters

Star-Tip 1050

Gardening Tips for successful and beautiful Landscapes and Gardens


Have you taken a stroll through your landscape to inspect your drip irrigation? You need to check for adequate emitters for each plant as well as for plugged emitters. A frequent problem I observe is “mixed” emitters. Shrubblers or fast flow rate emitters on the same zone with drips (slow flow rate).

High Rate Shrubbler


High Rate Bubbler


Slow Rate Drip


Slow Rate Drip


If you have these different types mixed together on the same zone, some plants are going to be over-watered while others may be under-watered. If you reduce the flow on a high rate emitter to match a drip it is likely to perform erratically, due to its operation being at the border of its range.


Disadvantage of High Rate Shrubblers: If you have 35 shrubblers set at only 50% flow on the same ½” pressure regulated 50 ft. line, the emitters at the end have less than 90% flow of those closest to the valve. So, if they are adjusted further open, the actual increase in water in negligible. You wind up taking water from one plant to give to another. Also, because the water is applied more rapidly, it has less capacity to soak deeply into the soil. Shallow water – shallow roots! The perceived advantage of being able to adjust the flow rate has many negative trade-offs.


Advantage of Slow Rate drips: These are often pressure compensated. This means as you add a few extra to the line (more plants) the flow rate will remain constant. The water for the new plants will not be at the expense of the established plants. Whereas the limit for high rate shrubblers on one zone is typically 25 (if fully opened), it is practical to have as many as 200 slow rate drips on the same zone without complications. Slow flow rate drips will allow much deeper penetration of water, giving you plants with deeper roots. Deep root systems mean healthier more drought tolerant plants.


The best watering for shrubs and trees is slow and deep. Expanding the watering zone as the plants mature and routinely inspecting for trouble. Set your clock for an hour or more with slow rate drips, and avoid frequent every day scheduling, even in the heat of summer!

If you do happen to have you trees or shrubs on the same zone as your lawn, then and only then would you need high rate emitters. The SNWA does not require that you water your shrubs in 4 minutes. 4 minute run times are suggested for lawns!


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