Question
I have several Thompson's that are leaning and one is on the ground.  The roots are in the ground and the top is green.  I have several others that are starting to lean in the middle of the trunk.  What do I do? What causes this to happen?

Answer
Hello Linda,
If the leaning starts at the ground (as if it is not steady, and wants to tip over), than the soil is loose and might want to consider transplanting. This is also caused do to overwatering, which doesn't give the soil a chance to harden as it dries. However, leaning is mostly due to phototropism, meaning the cacti wants to grow toward the direction of sunlight. If they are in a shaded area (or in some point in time), than it is definitely phototropism. Trying to lean the plant back into place is a bit tricky, and it takes time. A LOT of time. And it would look unattractive, as placing an opaque object in the direction of the light is unwanted.

But don't worry. As long as the plant gets atleast 4 hours of sunlight, and is in a bright place, than the plant will be okay.