Keeping a garden looking its best requires irrigation—especially in areas like Austin, Texas, where summer heat scorches plants. When a homeowner wanted to add plants along the back of her deck, landscape contractor Lee Gilliam knew they’d have to add a new irrigation zone to her system.
You Need to Find the Clock First
The first step in adding an irrigation zone is locating the control clock for the existing irrigation system. This device activates and deactivates zones according to the homeowner’s settings. Open the cover to determine if there are any open zones. If so, adding an irrigation zone will be much less of a challenge.
Pro Tip: On a This Old House project in Texas, landscape contractor Lee walked homeowner Kristen through this exact process. After locating the controller in the garage, Lee explained: “We have five zones and we have space to add another zone. So what we’re going to do is put another zone in for the drip that we’re going to do for the containers.” Finding that open slot made the entire project far simpler.
Keep in mind that adding a new zone may require a licensed professional. As Lee noted during a This Old House project, he wasn’t licensed to do irrigation work in that state, so he brought in a licensed installer. Before starting any work, check your local licensing requirements—regulations vary by municipality.
Spray and Drip Don’t Mix
Tying into an existing spray line might make sense, but only if you add another spray zone. Spray lines discharge a lot of water at once, so they don’t need to run long. Drip zones, however, need to run much longer to sufficiently water plants. Mixing the two will either flood part of the garden or prevent it from getting enough water.
Drip systems also use far less water per hour than spray zones. As landscape contractor Roger Cook explained on This Old House, spray-style emitters can put out as much as 10 gallons per hour, while drip emitters may deliver only one gallon per hour. That enormous difference in flow rate is precisely why combining them on a single valve leads to problems—one type will always be over- or under-served.
Pro Tip: A drip zone requires its own dedicated valve and a pressure-regulating kit to function properly. As irrigation contractor Aaron explained during a This Old House project, the drip kit includes “a pressure regulator and a filter that kind of regulates the amount of water towards those drip lines.” A typical drip kit drops system pressure down to around 40 psi—far lower than what spray heads need—which is another reason the two systems can’t share a single zone.
Find the Main Line
Instead of mixing lines, tie into the main line. The main line is the main water supply feeding the system. The zones branch off the main line, spreading out into the garden. Find that main line and plan to tie it in with a new zone valve.
Use a Proper Zone Valve
Once you tie into the main line, you’ll need to install the propeller zone valve. Spray valves have much higher pressure while drip valves are set for much lower pressure. Pairing the right valve to the system allows the nozzles or emitters to supply the correct amount of water for the time period chosen.
These valves feature solenoids that tie directly to the control clock. At the preset time, the clock sends a signal to the solenoid, telling it to open and allow the water to flow. When the present time is over, the solenoid shuts.
Keep Local Restrictions in Mind
Make sure to keep local restrictions in mind. Some areas dictate when a homeowner can water their plants or how often. Drip irrigation is considered a controlled form of irrigation and is often less regulated, as the water drips directly into the soil rather than being sprayed and evaporated.
Resources
- Irrigation installation done by Thrive Outdoor Solutions, LLC.
- New valve installed, fit for drip irrigation—Hunter Drip Control Zone Kit w/ pressure regulator 40 PSI
- Dripline—¼ emitter tubing with 6 in. spacing
- Plants—Tangerine Beauty crossvine
- Soil—Happy Frog potting soil
- Compost—Organic compost with mycorrhizal fungi
- Planter boxes—Lightweight outdoor 46” x 17” x 19” trough planter box
- Planter Spacers—2 in. Brown square furniture cups
If freezing temperatures are expected in the winter, protect the plant by adding frost protection blankets around the plant and planter.
