Adding a drip irrigation zone for a vegetable garden or perennial bed to an automated irrigation system requires an available "station" remaining in its controller. You can determine this by contacting the contractor who installed your irrigation system, or by inspecting the controller wiring. If the capacity exists and you have some fundamental knowledge of irrigation plumbing and wiring, you can do it yourself. If the capacity is there, but you don't feel comfortable tackling the project, your irrigation contractor can do it for you.
Valve Installation and Wiring
Install an irrigation valve on the main supply line for the system. If an existing valve box is located near the area to be irrigated, use that as a convenient spot to join the valve to the supply line. If not, run an additional line from the main supply to the general vicinity of your irrigated area and install the valve there.
Dig a trench between the valve location and the controller for the irrigation system.
Run a two-wire cable between the controller and the valve.
Connect the two wires in the cable to the wires on the valve solenoid using waterproof wire connectors.
Connect the white wire in the cable to the common connector in the controller and the colored wire to the available station connector.
Filter, Regulator and Line
Attach a 100-mesh filter to the outlet side of the valve.
Attach a 30 psi pressure regulator to the outlet side of the filter.
Attach a 3/4-inch polyethylene hose adapter onto the outlet side of the pressure regulator, then attach a section of 3/4-inch polyethylene hose to the adapter.
Hose Layout and Emitters
Run the polyethylene hose throughout the irrigated area. Do not bend or kink the hose. Use elbows to make right angle turns. Use tees to branch the line to various parts of the area. Limit the total length of line to 200 feet.
Bend the terminal end of each hose section back on itself and clamp it with a plastic cable tie. Leave one terminal end open for Step 3.
Place the open end of the hose in a 5-gallon bucket. Manually open the valve. Time how long it takes to fill the bucket. Divide 5 by the number of seconds it took to fill the bucket and multiply that result by 3,600. For example, if it takes 20 seconds to fill the bucket, you have 900 gallons per hour (5 / 20 = .25 x 3,600 = 900). Multiply 900 by a safety factor of .75 and you have 675 gallons per hour available to your system.
Punch a hole in the polyethylene hose near a plant you want to water.
Snap the fitting off a stream-spray bubbler. Push the beveled end of the fitting into the punched hole in the polyethylene hose.
Cut a length of 1/4-inch vinyl micro-tubing that will reach from the polyethylene hose to the base of your plant.
Press the micro-tubing over the fitting in the polyethylene hose and over the fitting on the side of the stream-spray bubbler.
Push the stake of the stream-spray bubbler into the soil at the base of the plant. Repeat for all plants. Each bubbler can be adjusted from 0 to 10 gallons per hour. Using the previous example, if every one of them is set wide open, 67 bubblers can be installed on the system. If they're adjusted to a maximum of half their flow rate, 134 can be installed.
Adjust the output at each bubbler to match the requirements of the plant it services.