There are two parts of the in-ground irrigation system that impact the back bedroom bed.
First, the main irrigation water supply line runs thru the entire bed, about 8 to 10 inches below the surface. It runs roughly parallel to the back bedroom exterior wall, from 25 to 27 inches from the concrete wall that seals off the foundation. When it gets to the Iris bed, it's only 12 inches away from the bed. On either end, it then disappears under the river of rocks.
The other related irrigation system component is for the bed itself. This is all done in 1/2 inch PVC, as an extension of Zone 9. We ran a 1/2 inch PVC line right next to the house, with pop-up sprinkler heads that spray out from the house, covering the bed. Any over-spray will go onto the river of rocks, and water the monkey grass between the rocks.
There are 4 heads equally spaced along the back of the house in a straight line from the corner to the Iris bed. We jog out slightly to get around the Iris bed stone work and continue to the end of the bed for one last head. Each head should be just at ground level, and then pop-up 4 inches. As with our other new beds, we are using the Rainbird 1800 series heads.