Some controllers have add-on aftermarket adapters that let you add more stations to the controller. You can also check the flow requirements of your other zones and if they can be combined you can plug two valves into one station on the controller.

I would never put just one head on an area. You will get uneven watering. At the very least you need a second head so they can overlap each other, until recently most head preformed poorly right around the head so you needed another head to cover it.