The panicle hydrangea is member of the Hydrangeaceae, or hydrangea, family. Growers value it for its large, showy flowerheads, but it also has attractive foliage and interesting bark. People call it the panicle hydrangea because the flowerheads develop in cone-shaped panicles of individual flowers. A panicle is a branched stalk of flowers that grows from the main flower stem. These flowers are interesting because soil composition often affects hydrangea flower colors.
Typically, the nature of the soil has a direct effect on plants. The availability of aluminum ions in the soil may change the flower color. Acidic soil with a pH of less than 5.5 usually produces blue flowers, while soils with a pH greater than 5.5 may produce pink flowers. The soil pH generally does not affect white-flowering panicle hydrangeas. The white to creamy-white flowers bloom in late summer and early autumn, becoming pink-tinged as they mature.
Panicle hydrangea flowerheads have both tiny, fertile flowers and larger, sterile flowers in conical panicles that are often 3 to 8 inches (7 to 20 cm) tall. The sterile flowers are the plant's flags that attract insects to the smaller fertile flowers. People often mistake the showy, petal-like sepals for flower petals. A sepal is an adapted leaf structure that encloses and protects the flower bud, petals, and other flower parts. These sepals often dry out and may remain on the plant throughout the winter months.
Growers usually plant panicle hydrangeas as specimen plants because they may reach heights of 10 to 22 feet (3 to 7 m) and a width of 8 feet (2.5 m). Others plant them in groups, such as a shrub border or a living fence. Several growers use them as container plants and train them to climb a wall or fence. Some people plant them at tree bases and encourage them to climb the tree trunk.
The shrub's attractive mid- to dark-green leaves range from 3 to 6 inches (7 to 15 cm) long. They are ovate-shaped, coming to points at each end. Typically, they have finely toothed edges. They grow up the flower stems in opposite pairs.
Many crafters use dried hydrangeas in flower arrangements and other fall decorations. Often people bleach or dye the flowerheads to make them more colorful. These decorations are so popular that usually crafters can buy dried hydrangeas in bulk.
If eaten, parts of panicle hydrangea plants may cause mild stomach upset. Frequently, the foliage may aggravate skin allergies. Growers often wear protective clothing such as gloves and long sleeves when working with the plant. The same skin irritation problem usually is not evident with the dried products.
Generally moist, well-drained soil in the sun or partial shade provides the ideal growing conditions for panicle hydrangea shrubs. Gardeners often plant it in areas that are sheltered from wintery, drying winds. To achieve superior flowerheads on cultivars, in the spring growers prune back the previous season's shoots to have only a few buds above the woody framework. They propagate the plants by sowing seeds or by rooting deciduous softwood cuttings in early summer or hardwood cuttings in winter. Typically, evergreen varieties do best when growers root semi-ripe cutting of non-flowering shoots in the summertime.
