Are you sure you want to turn on 13 valves at the same time? That’s going to draw at least 13 * 0.2 = 2.6 amp. In practice the current draw may be less because the transformer’s output voltage typically drops as you draw more current from it, resulting in less current drawn per station.
In any case, if you plan to turn on no more than 4-5 valves at the same time, I think the controller can totally handle that. If you want to turn on more than 6 to 7 valves, using relay is probably a better idea.