KC Gardens

Smooth hydrangeas make for a beautiful, easy-care addition to your summer garden

Smooth hydrangeas are just now coming into bloom in Kansas City. The Annabelle variety has flowers that grow up to six inches or more and will remain attractive through fall.
Smooth hydrangeas are just now coming into bloom in Kansas City. The Annabelle variety has flowers that grow up to six inches or more and will remain attractive through fall.

Great shrubs for the landscape are sometimes hard to find. A great shrub is one that has good color, healthy flowers, is easy to care for and isn’t fussy. One of the best shrubs that fits this category is Hydrangea arborescens, commonly called smooth hydrangea. This plant has it all for local landscapes.

Smooth hydrangeas are also called wild hydrangeas; their native range includes a large portion of the southeast United States. In fact, the Department of Agriculture’s plant finder lists them as native in Kansas and Missouri. I must admit I haven’t seen this plant in the wild, but that’s just indicative of its adaptability.

Smooth hydrangeas are often grown for their large, showy flowers. In particular, the standby variety Annabelle has large, white rounded flowers that can grow up to 6 inches or more. The plant is just now coming into bloom in Kansas City, and the flowers will remain attractive through fall, although the color does fade.

The plant is adaptable to grow in various locations, including those with sun, partial sun and even partial shade. The trick to growing smooth hyrdangeas in more sun is an even supply of water. Although it can survive on less water, it’ll do best during the heat of summer with an even supply. I’ve found it’s pretty tolerant of most moisture patterns and soils.

Hydrangeas are a nice size, too. They typically reach around 3 feet, and they’re well-behaved plants that form a tidy clump. They’re slow spreaders, quickly developing into a mass of color during the summer bloom period.

Pruning is simple, even for those who don’t enjoy it. Each spring as the new growth appears, simply cut the old branches to the ground — yes, all the way to the ground — leaving only the lowest set of developing leaves. By removing all the old growth, the plant renews itself with strong branches for flowering.

The plant blooms on new growth, and the best flowers are produced from a strong cane. Lack of harsh pruning will cause the over-sized, heavy flowers to flop. Flopping is even more prevalent in shade. Sunnier locations result in stronger stems that will support the large flowers.

Recent breeding work has resulted in a number of new varieties coming onto the market, with newer updates in development. Another white variety on the market is the Incrediball, which can have even larger white flowers than Annabelle. They often reach up to a foot across. There has also been a recent trend for breeding shorter plants, such as Invincibelle Wee White.

The latest breeding trend is pinkish flowers. First on the market was Invincibelle Spirit, which has now been upgraded to Invincibelle Spirit II. Coming next year are pink introductions such as Incrediball Blush, Invincibelle Ruby, and Invincibelle Mini Mauvette.

Smooth hydrangeas are an absolute winner for Kansas City gardens, especially now that they’re blooming into their full glory. If you don’t yet have this plant, make sure to find some space for it.

Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Got a question for him or other university extension experts? Email them to garden.help@jocogov.org or visit KCGardens.KansasCity.com.