About 80 species of shrubs and climbers belong to the genus Ortensia, in most cases with deciduous foliage. The shrubs, very beautiful, resist particularly well to low temperatures, requiring special precautions only when the cold becomes quite intense. The most typical species is the hortensis, a round shrub capable of reaching a height and a diameter of about 4 meters, with oval and coarsely toothed leaves. The varieties of this species are divided into two groups, the most numerous of which is the Hortensia, whose varieties differ from each other mainly in the color of the flowers, which vary from pink to blue.
Hydrangeas are acidophilic plants and should be planted in autumn or early spring, in fertile and fresh soil, in well-sheltered positions, under tall trees or against a wall or a hedge. All hydrangeas are good, in spring a fertilization with well decomposed organic fertilizer. Hydrangeas can also be grown in pots, using large containers. In any case, they will be kept in pots only for one season: after the first flowering in fact, they will be planted in the ground, as already specified in sheltered positions.