The optimal growing location for hydrangeas is outdoors where they can thrive and grow in abundant sunshine. Although most gardeners place hydrangea shrubs outdoors, it may be possible to grow hydrangeas inside if you have a sunny window, pay close attention to the temperature of the environment, and provide proper water amounts. Allowing a hydrangea to enter dormancy during the winter will give it a required rest time, which will enable the plant to continue to thrive energetically.
Fill the planting container approximately half-full of potting soil. Place the hydrangea into the container at the same depth as it was growing in the temporary container. Fill additional potting soil in around the roots of the shrub until you fill the container to the top with potting soil.
Provide water for the hydrangea immediately after planting it to saturate the soil. Place the hydrangea in a growing location that receives direct sunlight. A cool growing location (below 70 Fahrenheit) is ideal.
Water a potted hydrangea regularly to keep the soil evenly moist. Place the container in a sink to allow the water to drain out the bottom drainage holes. Wait until the water drains completely and then place the container back into its regular growing location.
Fertilize the potted hydrangea twice per growing season--once in the spring and once in midsummer. Move the container to the sink to allow for drainage. Mix the fertilizer according to package recommendations for the size of the growing container and pour the fertilizer carefully onto the soil.
Clip off spent blossoms with the pruning shears when the hydrangea finishes blossoming. Examine the hydrangea for dead branches and remove these from the plant by cutting them off just above the base of the hydrangea. Shape the hydrangea to control growth and keep it attractive. The time for shaping a hydrangea depends upon when the hydrangea blossoms. If a hydrangea blossoms in the spring, shape it immediately after it blossoms. If a hydrangea blossoms in the summer, shape it early in the growing season before it blossoms. Do not remove more than one-third of the growth at one time.
Allow the hydrangea to enter dormancy in the autumn. Decrease the watering frequency and amount, watering only when the soil dries slightly and then watering lightly just to moisten the soil.