1. Press on both plants until you can see the clocks and the small hint where the right plant was.
2. Select the magnifying glass in your inventory and press the small picture on the wall to see the hint.
3. Now hold your phone upright. Tilt the top of the phone in the direction the arrows are pointing on each clock from left to right. The hint shows that holding your phone straight upright is how to get the last clock. Use this as a guide.