Hydrangeas are often grown in warmer gardens, as they have a long blooming period and thrive in areas with mild winters and little freezing. Even in colder regions hydrangeas grow well as a potted plant, whether grown inside the home year-round or brought inside for winter. Whether it is grown outdoors or in a pot, caring for the hydrangea after the flowers wilt ensures the plant remains healthy and produces another profusion of blossoms the following year.
Remove spent flower stalks as soon as they fade, to prolong blossoming. Snap the stalks off at the base and dispose of them. This also keeps the hydrangea attractive.
Prune the hydrangea in late summer after it has stopped producing new flowers. Cut off the older stems, which will have become dark brown and woody. Trim them to where they emerge from the ground with a pruning saw or shears. Avoid cutting the newer green growth, as these are the stems that will produce next year's flowers.
Fertilise the hydrangea after pruning to encourage healthy new growth. Use an 8-8-8 fertiliser at the rate recommended on the package for outdoor hydrangeas, spreading it on the soil 3 feet away from the main stem. Fertilise potted hydrangeas with a soluble houseplant food at the rate recommended on the package.
Water the pruned and fertilised hydrangea until the soil is evenly moist but not soggy, as this helps it begin soaking up the fertiliser nutrients as soon as possible. Water outdoor hydrangeas until the top 6 inches of soil feel moist. Water potted hydrangeas until the excess moisture begins draining from the bottom of the pot.
Lay a 2- to 3-inch layer of mulch around outdoor plants in the autumn after flowering. Mulch preserves soil moisture throughout winter and protects the roots from light frosts. Bring outdoor potted plants indoors before the first seasonal frost, if applicable.
Potted hydrangeas do not grow into shrubs like their outdoor counterparts, so pruning should be limited to shaping and the trimming out of old, dead stems.
Outdoor hydrangeas do not need to be pruned until they are five or six years old. Pruning younger, un-established plants may inhibit blooming.