Hydrangeas are popular shrubs for the home landscape. Their large, elegant flowers charm homeowners and visitors alike throughout the summer months. An added bonus to most hydrangea flowers is that they make excellent cut and dried flowers. You can bring the blossoms inside to brighten the indoor landscape.
In the past decade, there has been an explosion of new cultivars with varying flower colors and shapes. With all this variety there is likely a hydrangea (or two) that will work in your landscape.
Several hydrangea species can be grown in Iowa. Two species (smooth hydrangea and panicle hydrangea) are easy-to-grow, reliable performers. The others can be a bit more challenging.
Smooth Hydrangea | Panicle Hydrangea | Bigleaf Hydrangea | Mountain Hydrangea | Oakleaf Hydrangea | Climbing Hydrangea | More Information
Smooth Hydrangea
One of the most durable and reliable of the hydrangeas is smooth hydrangea (Hydrangea aborescens). This 3- to 5-foot shrub flowers freely from June to September. The flowers are rounded and change from an apple green to creamy white during the summer. Flowers are also showy in the fall as they fade to tan and persist into the winter. ‘Annabelle’ is one of the most popular cultivars and is noted for its large (almost 1-foot-diameter) flower heads. This cultivar can be spotted from a great distance. The flowers are often so heavy they weigh the stems to the ground giving the shrub a “weeping effect”. For plenty of flowers and dense, dark green leaves, plant smooth hydrangea in partial sun to partial shade. Smooth hydrangea is tolerant of many soil types but thrives in moist, well-drained soils. This is one of the cold hardiest of the hydrangeas surviving well into Minnesota.
Cultivars of Smooth Hydrangea
| Cultivar | Height x Width (in feet) | Comments |
|---|---|---|
| Annabelle | 3-5 x 4-6 | Large white snowball flowers |
Bella Anna™ ('PIIHA-1') | 5 x 5 | Pink flowers |
Incrediball® ('Abetwo') | 5 x 6 | Large white snowball flowers |
Invincibelle® Ruby ('NCHA3') | 3 x 2-3 | Pink to ruby red flowers |
Invincibelle® Spirit II ('NCHA2') | 3-4 x 3-4 | Pink flowers that fade to green |
White Dome® ('Dardorn') | 5 x 4 | White lacecap flower |
Panicle Hydrangea
The panicle hydrangea (Hydrangea paniculata) blooms later than the smooth hydrangea, often not flowering until July. But the 6- to 12-inch-long, cone-shaped, creamy white flowers are equally persistent. As the flowers age, they often fade to pink. This is the largest of the shrub-type hydrangeas, sometimes reaching 15 feet or more in height. There are many wonderful cultivars of this species including ‘Grandiflora’ or PeeGee. Once again the flowers are so large they often weigh down the branches. Panicle hydrangeas are vigorous growers and can be pruned as small trees. Panicle hydrangeas perform best in moist, well-drained soils in full sun to partial shade.
Cultivars of Panicle Hydrangea
| Cultivar | Height x Width (in feet) | Comments |
|---|---|---|
| 'Grandiflora' | 12-18 x 8 | Large white flowers that fade to pink or green |
| 'Limelight' | 8 x 6 | Greenish white flowers that blush pink |
Little Lime® ('Jane') | 3-5 x 3-5 | Lime green flowers age to pink |
Little Quick Fire® ('SMHPLQF') | 3-5 x 5 | Creamy white flowers that turn a deep pink |
Pink Diamond ('Interhydia') | 8-10 x 8-10 | White flowers turn pinkish |
Pinky Winky® ('DVP PINKY') | 8 x 8 | White flowers that fade to pink |
Quick Fire® ('Bulk') | 6-8 x 6-8 | Creamy white flowers that turn a deep pink |
| 'Tardiva' | 8-10 x 6 | Large, open white flowers |
Vanilla Strawberry™ ('RENHY') | 6-8 x 5 | Flowers change from vanilla white to strawberry red |
White Diamonds® ('HYPMAD I') | 5 x 5 | Open white flowers |
Bigleaf Hydrangea
The bigleaf hydrangea (Hydrangea macrophylla) has the colorful blooms that are commonly sold in florist shops and supermarkets as a cut flower. You will find cultivars with two different flower forms. Mophead types have a ball-shaped cluster of almost all sterile flowers which have large petals. Lacecap types have a more flat-topped flower cluster with large petaled sterile flowers around the outside and small petal-less fertile flowers in the center. It is the only hydrangea species where the flower color depends on soil pH – blue in acidic soils and pink in alkaline soils. In Iowa, most bigleaf hydrangeas are purplish-pink due to our slightly alkaline soils. Many of the newer introductions bloom on new growth, in addition to the previous season’s growth. Despite their improved flowering habit, some cultivars are finicky and bloom erratically. When purchasing plants, check the label for cold hardiness recommendations as there are several cultivars that are not hardy in zone 5 for Iowa.
Cultivars of Bigleaf Hydrangea
| Cultivar | Height x Width (in feet) | Comments |
|---|---|---|
BloomStruck® ('PIIHM_II') | 3-4 x 4 | Pink, blue, or purple |
| 'Blushing Bride' | 6 x 6 | White flowers that age with pink blush |
Endless Summer® ('Bailmer') | 3-4 x 4 | Blue, purple, or pink flowers |
Let’s Dance® Moonlight ('Robert') | 2-3 x 2-3 | Pink or blue mophead |
Twist and Shout® ('PIIHM-I') | 5 x 5 | Pale pink or blue lacecap flowers |
Mountain Hydrangea
Mountain hydrangea (Hydrangea serrata) is closely related to bigleaf hydrangea and has many of the same attributes. The flowers are blue or pink depending on soil the soil pH and if you adjust the soil pH in the same was as you would with bigleaf hydrangea, you will get similar results. Plants are also not always reliably hardy - especially the straight species. However, those cultivars that are hardy to zone 4 or 5 flower more reliably in colder climates than bigleaf hydrangea. As with bigleaf hydrangea it is important to select a cultivar that blooms on both old growth and new growth so if winter destroys the old growth you can still get flowers the following growing season.
Mountain hydrangea is a smaller statured plant than bigleaf hydrangea. It prefers cooler temperatures and does well in shade or part shade locations. The flowers are always a lacecap type with small petal-less fertile flowers in the center of the cluster and large petaled sterile flowers around the outside giving the plants a more open (lacy) and informal look. As with bigleaf hydrangea, be sure to check the hardiness zone as not all cultivars are reliably hard to zones 4 or 5.
Cultivars of Mountain Hydrangea
| Cultivar | Height x Width (in feet) | Comments |
|---|---|---|
Tuff Stuff™ ('MAK20') | 3-4 x 2-3 | Pink, blue, or purple |
Tuff Stuff Top Fun® ('SMNHSG') | 2-3 x 2-3 | bright burgundy stems |
Tiny Tuff Stuff™ ('MAKD') | 1.5-2 x 1.5-2 | Small statured |
Oakleaf Hydrangea
One of the most interesting hydrangea species is the Oakleaf hydrangea (Hydrangea quercifolia). The coarse leaves are 3 to 8 inches long and shaped like oak leaves (hence the common name). The foliage is also noted for its attractive, red-burgundy fall color. This 3- to 5-foot shrub has showy, cone-shaped, creamy white flowers in June and July. Like the panicle hydrangea, its flowers often develop pinkish undertones as they mature. The oakleaf hydrangea is considered hardy to USDA Hardiness Zone 5. It should perform well in protected sites in southern Iowa, but may not survive in northern areas of the state. It prefers partial shade in fertile, moist, well-drained soils in areas protected from harsh winter winds. Several cultivars are available.
Cultivars of Oakleaf Hydrangea
| Cultivar | Height x Width (in feet) | Comments |
|---|---|---|
Gatsby Star® ('Doughill') | 6-8 x 8 | Double greenish white star-shaped flowers |
Snowflake ('Brido') | 6 x 8-10 | Double flowers that fade to rosy pink |
| 'Vaughn’s Lillie' | 4 x 5 | Large flower heads |
| 'Alice' | 12-15 x 12-15 | One of the largest of the oakleaf hydrangeas |
Climbing Hydrangea
Not all hydrangeas are shrubs. One such example is the climbing hydrangea (Hydrangea petiolaris). It clings easily to tree bark and various structures and can climb to 50 feet. The white flowers appear in 6-to 10-inch-diameter, flat-topped corymbs in early July and persist for several weeks. The glossy dark green leaves provide the perfect backdrop to show off the blossoms. Another interesting feature of this plant is its exfoliating brown shaggy bark which is rather striking in the winter landscape. Climbing hydrangea thrives in partial shade in a moist, fertile, well-drained soil. Plants are slow to establish, taking a few years before vigorous growth begins. Support will also be needed as the plants become established and to direct growth. Japanese beetles may partially defoliate plants in some years. Climbing hydrangea is hardy to USDA Hardiness Zone 4.
You may find climbing hydrangea listed under several different scientific names. There are at least three different species of climbing hydrangea found in garden centers. Additionally, there has been several name changes in recent years. Don't be surprised while shopping if you see climbing hydrangea listed as Hydrangea anomala subsp. petiolaris. You may also find the closely related, but different species, Japanese climbing hydrangea (Hydrangea anomala). The "false" hydrangea vine, once known by the name Schizophragma hydrangeoides (hence the name false hydrangea), is now classified as Hydrangea hydrangeoides, making the common and scientific name a bit peculiar (how is it "false" when its genus is Hydrangea and why does its species name mean hydrangea-like when its a hydrangea?) To make the name a little less odd, just refer to this species as Japanese hydrangea vine instead! All of these species (regardless of what scientific name they currently have) are grown in the same conditions and look almost identical except to the trained botanist's eye.
More Information
For more on pruning hydrangeas, see this article: Pruning Hydrangeas
Photo credits: 1: Cindy Haynes; 2: Cindy Haynes; 3: Cindy Haynes; 4: Irina/AdobeStock; 5: Aaron Steil; 6: salita2010/AdobeStock; 7: Cindy Haynes; 8: Cindy Haynes; 9: Cindy Haynes