If you are simply transplanting a new plant you just purchased from the grower's pot it came into a more aesthetically pleasing pot, use the same size pot. However, if you are re-potting because your plant has outgrown its current pot, choose a pot that is 2-4 inches in diameter larger than the existing pot. It is essential to remember plants need to root into the soil and develop in a circular motion around the base root of the plant. On average, you should allow for a couple of inches of room around the edges of the pot for the roots to grow. Where the roots won't reach in the pot (vertically or horizontally), the left-over soil will allow for excess water drainage which is crucial for plant survival.