Hydrangeas have been garden favorites for many years and understandably so! The diversity found in this family of flowering shrubs is impressive. They are usually grown for their large clusters of showy summer flowers but their value in the landscape goes well beyond their beautiful blooms!
There are five different types of hydrangea and each has its own unique characteristics. Most thrive in full sun or part shade and they prefer moist, well-drained soil that is rich in organic matter to perform their best. For pruning purposes, it is VERY important that you know which type(s) you have in your garden - so SAVE the LABELS!
H. arborescens - A wonderful species that includes the popular cultivar 'Annabelle' which produces huge white flowers up to 10" across. These hardy hydrangeas bloom from June - August and grow 3'-5' tall. This species prefers partial shade. The flowers are excellent for drying and using in fall arrangements. Zones 4-9.
Hydrangea paniculata - This tall variety grows as a large, upright, spreading shrub or it can be developed into tree form through pruning. It produces large conical flower clusters from July to September and grows 10' - 25' tall. One of the most cold hardy types of hydrangea. Zones 3-8.
Watch Mark's video tip on Hydrangea 'Tardiva' and how to train it to tree form.
H. macrophylla - These are commonly grown hydrangeas that produce large blooms on wood produced the previous year. This species includes the mophead hydrangeas with their huge round flower heads and the lacecap hydrangeas which bear round, flat clusters of tiny fertile flowers surrounded by a ring of showy open petals. The bloom color may be pink or blue depending on the pH of the soil they are grown in (blue in acidic soil, pink in basic or alkaline soil). The flowers of H. macrophylla are excellent for drying. This species is less hardy than the other species and in colder regions of Zone 6, they may grow well but not be "bloom hardy" meaning that the plant survives but never or rarely flowers because the flower buds are damaged during the winter. Protect the stems in winter by packing them with straw, tying them together, and wrapping them with burlap.
Recently, several hardy reblooming cultivars have been developed from Hydrangea macrophylla. These include the Endless Summer Collection. These shrubs bloom on both new and old wood and are hardy to Zone 4.
Hydrangea quercifolia - Named for its deeply lobed oak-shaped leaves, Oakleaf hydrangea is noted for its brilliant deep reddish fall color. Large erect clusters of white flowers grace the shrub in summer with peak bloom in July. This species grows 4' - 8' tall and is hardy in Zones 5-9.
Hydrangea anomala ssp. petiolaris - This is a hardy climbing hydrangea which can reach up to 60' - 80' in height if it is left unpruned. The strong vines have attractive cinnamon brown bark and beautiful clusters of white flowers from June - July. They grow well on brick or stone walls, or on arbors and trellises. Zones 4-7.
These are amazing shrubs and every gardener should find a place for at least one or two in the garden!