Hydrangeas (H. macrophylla) are desirable for their large, showy clusters of blooms and their deep green leaves. These favorite plants of home gardeners are most commonly grown outdoors, where some varieties can reach sizes of over 6 feet tall and wide. Potted hydrangeas are often given as gifts, especially for occasions such as Easter and Mother's Day, and can be grown indoors. While most potted hydrangeas do not easily transition outdoors, with proper care they may be coaxed into blooming twice in one growing season.
Place your hydrangea where it will receive bright light, but not be exposed to the direct rays of the sun, as this can scorch the delicate leaves of the shrub. Outdoor hydrangeas do well in partial shade. Indoor hydrangeas should be placed near a window that faces south, or a window that has bright but filtered light, such as that through a sheer curtain.
Hydrangeas thrive in rich, loamy soil. Choose a potting soil that is well draining but has added nutrients in the form of organic matter, such as one that has included peat moss, sand, perlite or leaf mold. Potting soils designed for woody ornamental (flowering) shrubs will work.
Hydrangeas need cool, moist soil to thrive. Never let the soil dry out, but do not overly water it either. The soil should be barely moist to the touch at all times, not soggy or saturated. Potted plants lose water quite rapidly, so you will most likely need to water two or three times per week during the growing season. Indoor hydrangeas do not need to be fertilized, according to information published by Denver Plants.
Cut hydrangeas down to half their height once they have finished flowering, but continue to water them. When winter arrives, move the plant to a dark, cool room (but one that is frost-free) and water it sparingly. In the middle of winter, move the plant to a slightly warmer and brighter room. Gradually increase the frequency of watering and exposure to light as spring arrives, and the hydrangea may bloom again the next summer.
Hydrangeas can suffer from many common houseplant pests, including spider mites. White flies in particular like to camp out on the underside of the plant's broad leaves. If you notice an insect infestation, try taking the hydrangea outside and hosing the insects off with a blast of water. Or, spray the plant with an application of insecticide.