Hello, and thank you for contacting us. I suspect your plant is yellowing because the soil is too wet at root-level. Potted plants must have good drainage. Proper planting involves:

1. The right size pot with good potting soil. Do not place anything in the bottom of the pot for drainage. 
2. Set the pot on some small stones or a trivet so that excess water can drain freely from the pot.
   
3. Use a drainage dish to catch excess water.

Here are a couple of articles which explain the problem with perched water tables. This can occur both in pots as well as the garden. Often plants begin to look as though they are dry and in need of water when in actuality the roots are rotting from too much moisture.

http://www.unce.unr.edu/news/article.asp?ID=2247

https://pss.uvm.edu/ppp/articles/hseplant.html