Generally, there is more than one plant in each hanging container. Separate the plants and transplant them into separate hanging containers for the remainder of the growing season. Remove the plant from the pot and separate the root ball into several smaller plants. If the plants are not root-bound, you should be able to separate the roots with your fingers. You may need to divide the root ball with a sharp knife. Transplant the plant sections into pots that are slightly larger than the plant.
Once a plant outgrows the hanging container, the added foliage adds additional weight to the hanger. Many of the plants look just as good in tall containers as they do in the hanging planter. Transfer the plant to a larger container that is tall enough for the foliage to hang as it did in the hanging pot. You can use a shorter container as long as the diameter of the new pot is larger than the existing pot. Set the pot on a banister or other structure that allows the foliage to hang as it is intended.
Many potted plants work well as bedding plants in the landscape. When the plant gets too big for the pot, relocate the plant to a section of the garden. If your potted plant is made up of several plants, transfer each one into a separate area or space them together for more of a visual impact. Space the plants so the foliage does not interfere with the neighboring plants.
There are times when the foliage has grown longer than you want in a hanging plant. Pruning keeps the plant to a manageable size. A word of caution if you choose to use this method to control the size of the plant -- plants tend to produce more foliage when pinched back. Pruning works as a quick fix, while you decide whether you want to transplant or divide the plant.