Hydrangeas are typically planted in the garden, but can also be grown in pots where it is easier to control the soil's acidic level in order to manipulate the plant's flower color. Some varieties, such as Hydrangea arborescens and Hydrangea quercifolia, are especially suited to being grown in pots, according to North Carolina State University Extension. Protect potted hydrangeas during the winter, such as storing them in a garage or wrapping the container with a blanket.
Choose a pot that is at least 2 inches wider than the hydrangea's current container. However, if you plant it in an even larger pot, repotting your hydrangeas may not be necessary for three or more years. Choose a light-colored pot that will keep the soil cooler in the sun and one with drainage holes.
Fill the pot with commercial potting soil that has a pine bark base. Fill the container so that there is about 1 to 2 inches of space between the rim and the top of the soil.
Adjust the pH level to manipulate the bloom color. For example, a pH of 5.0 and below is necessary to bloom blue flowers. Read the label on your hydrangea to know what pH level is necessary for what color blooms. If the soil's acidity is not labeled on the potting soil, test it with a pH testing kit and add lime to lower the pH to a desired level. How much you need to add will depend on the current pH level, how much you want to change it and how much soil there is. A chart on the lime package will indicate how much to add.
Plant the hydrangea so that is planted as deep as it was previously planted in its old container. Lightly pack down the soil with your hands and add water slowly until water comes out the drainage holes. Add 1 to 1 1/2 inches of mulch, such as bark mulch, to help retain water and place the newly planted hydrangea in an area that is sunny most of the day, but gets light afternoon shade to protect it from the hottest time of the day.