The Hydrangeas are an important group of hardy and tender shrubs. About thirty-five species are know. Among the best known and most popular of Hydrangeas are the numerous varieties of Hydrangea macrophylla, also called H. hortensis. These are grown by commercial florists for use as pot plants in late winter, spring, and early summer.
The name Hydrangea is from the Greek hydor, water, and aggeion, a vessel, alluding to the cup-shaped fruits. These natives of Japan and Korea are hardy and woody; and in milder climates they can be planted in the garden after they finish flowering. They are not hardy if winter temperatures fall below 0�, so that excludes them from being used as a flowering shrub in our area.
Hydrangeas are particularly interesting because their color can be determined in the greenhouse. Flower color of all hydrangeas is affected by the degree of acidity or alkalinity of the soil in which they grow. Hydrangeas grown in acid potting mixtures will have blue flowers; those grown in alkaline mixtures will have pink flowers. One of the most striking shades of blue that I've ever seen in my life was in the gardens of Germany and Luxembourg. There the hydrangeas, or Hortensia as they're called there, grow in wonderful bushes with huge masses of bright blue flowers. It adds a color the to European gardens that we cannot begin to imitate here.
Thanks to Martha Stewart and others Hydrangeas are experiencing a resurgence of use as a cut flower. Fresh hydrangea blossoms are being shown in fresh flower arrangements and wedding bouquets. Dried hydrangeas add a delicate texture to permanent flower arrangements.
Caring for your hydrangea
It is lucky for you if you receive a gift of flowering hydrangeas! With proper care a Hydrangea purchased in bloom will bloom for six weeks or more. Hydrangeas do best in bright indirect or curtain-filtered sunlight with night temperatures of 55� to 72� and day temperatures of 68� to 72�.
Water plentifully as often as necessary to keep the potting mixture thoroughly moist. Never allow the mixture to dry out, or the plant will collapse. If this happens, immerse the pot in a bucket of water until the root ball is thoroughly soaked. Even if this treatment succeeds, however, the current flowering period of the plant will have been shortened. Fertilization is not necessary.