How can I get the width of a gameobject?

I'm a noob in Unity, trying to make a tower of hanoi style game.

I'm trying to make sure a gameobject (2D sprite, say, panda) stays to the left of another (say, bamboo), regardless of the former's size. I thought I could take the bamboo's location, and deduct the width of the panda from it.

Something like this:

Here's my code so far:

 foreach (GameObject panda in midBambooStack)
 {
     Vector3 newPosition = new Vector3(midBamboo.transform.position.x - panda.transform.lossyScale.x, panda.transform.position.y, panda.transform.position.z);
     panda.transform.position = newPosition;
 }

Unfortunately, whenever that code runs, here's what I get:

Any suggestions for a code that does the former pic? Thanks.