Container Size Select containers that are large enough to provide adequate soil volume for one growing season. A container may be used to grow multiple plants as long as there is enough soil to support them. Perennials, trees, shrubs, foliage plants will all need to be shifted up to larger containers periodically. Many plants do not suffer from being pot-bound. This can actually produce dwarfing effect that allows the plant to remain in the same container longer.
Excessive roots become a liability when they have displaced most of the soil in a container.
When this occurs, the water-holding capacity is gone and more frequent watering is required. Combining plants in one container gives you an immediate effect of fullness. It may become necessary to remove some of the plants over time to eliminate the domination of one plant over another. Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating. John C. Nye, Dean and Director.