Late summer is usually a tired time in the garden. Everything seems to be getting ready for a long winter's sleep and there isn't much blooming to keep things interesting. But if you have a few Hydrangea paniculata, your late summer garden goes from ho-hum to spectacular.
Unlike its cousin the Hydrangea macrophylla, this Asian native is hardy over a wide range of climates. Here is the U.S. it is perfectly happy in zones 3 through 8 and that takes in quite a bit of territory. In my town they are used by churches, banks and schools because they do quite well in commercial landscaping settings and even thrive in urban areas, although my little town of 3,500 hardly qualifies as urban. They require minimal care and attract few pests. The huge, cone shaped blooms start appearing in late June and are attractive well into autumn.
These deciduous shrubs started life in the hills and mountains of eastern Asia, much like our rhododendrons and mountain laurels here in North America. They grow from between 6 and 15 feet (2 m to 4.5m) and sometimes even larger. They aren't very picky about soil or pH, but you will get your best show in well-drained, moderately fertile ground with a neutral to slightly acid pH. While they are ok in full sun, they do best when given a bit of afternoon shade in the southern climate areas. Here in west Kentucky, they are often planted on the east side of buildings. In the northern parts of its range, they appreciate a bit of shelter from the worst of the winter winds. Hydrangea paniculata blooms on new wood so if late spring frosts are an issue, locating one against a wall or other heat sink helps prevent damage from spring freezes is a good idea. Unlike its mophead cousins, the paniculata can be trained to a small, single-trunked tree, which would be a showpiece in a small garden.
One of the best known hydrangeas in this group is the Hydrangea paniculata 'Grandiflora', also known as 'Pee Gee'. It has been around in western gardens since 1829 by Philipp Franz von Siebold, a German botanist and traveler introduced it. However, this group of plants has come quite a long way since then. Newer hybrids with larger flowers and stronger stems are now on the market and there are even cultivars with pink and purple blooms. Some even sport lime green flower heads. You can even control the bloom time since there are cultivars with early and late flowering. Since they bloom on new wood, you can control the size of these shrubs by pruning. Cut back the side shoots to 2” to 3” of the old wood for large blooms on the the resulting new growth. This process keeps the shrubs to a manageable size for around foundations and they are quite attractive when used this way.
The large panicles (which means cones) of flowers make wonderful cut flowers and florists even use dried ones in those types of arrangements. As the flowers age, the creamy white turns to a wonderful vintage pink and gives the plant a very old fashioned appearance. The wood is white and fine-grained and has been used in the past for walking sticks, fountain pens and other decorative items, so crafters should consider planting some, because both the flowers and the wood have uses. The mature flowers that are starting to turn pink also produce a lovely celery shade of green natural dye when an alum mordant is used. Butterflies and pollinators are attracted to the flowers as a nectar source and they are also a host plant for the Azure butterflies.
Not surprising, this versatile plant is also part of the Asian herbal pharmacy. Tea from the and roots is anti-inflammatory and has been long used to help arthritis pain. The crushed leaves have antibacterial properties that are good for wounds. Compounds containing Hydrangea paniculata have long been used in Asia as a circulatory aid and treatments for varicose veins, hemorrhoids and bruising. The bioflavonoid rutin is present in significant amounts and since it has anti-inflammatory properties, contributes to these uses. Rutin compounds also help alleviate the oral inflammation and mouth sores that some cancer patients experience. It also helps with the absorption of Vitamin C and the reduction of LDL cholesterol.
Summer-blooming shrubs are a wonderful addition to the garden and whether you decide to create a hedge or simply use one here and there as an accent plant, Hydrangea paniculata is an excellent choice because they thrive in a wide range of climates and are content with minimal care. They make an excellent choice for both new gardeners and those with experience. Commercial landscapers love them for the same reasons. They are widely available through mail order sources and local garden centers, so it is easy to include a few in your garden.