Potted hydrangeas are a popular flowering plant. Often presented as a springtime holiday gift in a small, foil-wrapped pot, potted hydrangeas have a reputation for being short-lived. But with proper care, they can be used as a houseplant or patio accent for many years. If you live in areas colder than zone 9, move your potted hydrangeas inside for the winter. In zones 9 through 10, most potted hydrangeas can be planted outdoors in spring.
Use standard, sterilized potting mixes for houseplants for your potted hydrangea.
Provide adequate light. If grown indoors, a bright, southern or western exposure is ideal. Outdoors, do not place your potted hydrangeas in direct, all-day sunlight. Bright morning sun and filtered afternoon sun are best.
Water abundantly, but do not let your hydrangeas sit in water. Allow the top 2 inches of soil to dry out between waterings. A gravel-filled, oversize drainage tray for your pot will collect excess water and provide added humidity for your hydrangea.
Grow your potted hydrangea in the coolest room in your house, and keep it out of direct heat from vents or other heat sources.
Pinch back dead or damaged leaves, and cut back uneven or leggy growth. Trim back stems that have already flowered. In early spring, reshape your hydrangea plant for size and balance.
Use a water-soluble, 10-10-10 fertilizer every month during the growing season, usually May through September.
Remove spider mites and aphids--common pests among hydrangea--with a cotton swab dipped in rubbing alcohol.
Repot your potted hydrangea every two to three years. Gently remove the plant from its container and use sharp scissors to cut away roots that are encircling the interior of the pot. Use a pot 2 to 4 inches larger than the last.