The 1-2-3 Rule is an easy way to remember how deep to water:

• Water small plants such as groundcovers, cacti, and annuals to a depth of 1 foot. (Grass should be watered to a depth of 10 inches.)
• Water medium plants such as shrubs to a depth of 2 feet.
• Water large plants such as trees to a depth of 3 feet.

A good way to test how deep you have watered is to use a soil probe - a sharpened piece of rebar or a very long screwdriver works well. About an hour after watering, push the probe into the soil. It will slide easily through wet soil but will be difficult or impossible to push dry soil. Water your plants and lawn until you can easily slide the probe to the recommended depth.

After plants are established, most water absorbing roots are located near the dripline - which is beneath the outer edge of the plant's canopy - not too close to the trunk or stem. Concentrate your emitters along the dripline of each plant. The water will spead down and horizontally as it soaks into the soil, reaching the entire root zone.

To estimate how much water it takes to wet the root zones of your plants, see the chart.

Now that you have an idea of how much water your plants need, you need to find out how much water your irrigation system applies. Keep in mind that there is a huge diffefence between the output of a drip emitter and a bubbler or garden hose. Compare how long it would take to apply 10 gallons of water through these methods:

• 2 minutes with a watering hose
• 10 minutes with a 1-gallon per minute bubbler
• 600 minutes or 10 hours with 1-galon per hour drip emitter

As you can see, drip systems should use multiple emmiters and run for longer periods of time to adequately water the root zones of your plants.