Unbalanced Growth

[cowhow]

I have two lemon trees, an Improved Meyer and a Lisbon.  The Lisbon is about 7' tall with a canopy of about 6'.  The Meyer is smaller and much younger, only being about 4' tall.  Both are healthy with regular blooms and fruit.  But, I need some advice about lopsided growth.  Both trees are growing primarily in one direction to the point they are lopsided and leaning.  The Meyer has just recently started two new sprouts growing opposite to old growth.

My question is how do I encourage more balanced growth?  The Lisbon gets trimmed regularly as it must live in a greenhouse.

 

[Millet]

Are  these tree growing in the ground or are they container trees?

[cowhow]

They are container trees. 

[Millet]

Do you rotate the containers so that both side of the tree get some direct sun?

[cowhow]

Actually, they receive about the same amount of sun on all sides now as they are more or less centered in the greenhouse.  Both trees came to me in this condition and have not improved over time.  The smaller Meyer has just now begun to have growth toward the unbalanced side.  The larger Lisbon I have had staked (tied) to its pot ever since I brought the tree home, which may have only made the situation worse.