Gardening and Horticulture - Dracaena Fragrans - what size pot??

Started a dracaena fragrans by taking a cutting from a mature plant.

http://www.hear.org/starr/hiplants/images/600max/html/starr_060826_8674_dracaena_fragrans.htm

My new plant was approx. 6" in length (2 months ago) and is growing well (10") now.

My question is how extensive of a root system does this plant have? How big a pot should my plant be planted in?

When I started the cutting, I simply placed the cutting in a small pot 4" and now am thinking it should be in something larger however, I have no idea what type of root system this plant has.

thank you!

Choose a container that is deep and large enough to allow root development and growth as well as proportional balance between the fully developed plant and the container. Container size controls the corn plant's growth in pots. If planted in the ground, the corn plant can reach 20 feet.

Do not go with less than 10" pot for 10-12" plant. You will need to transplant periodically so plant does not get root bound. Remember, the larger the pot, the larger the plant.

Can this plant thrive outside (potted) during the summer??