Caring for Hydrangeas

Hydrangeas: Selection and Care

 

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Hydrangeas are wonderful plants. Several hydrangea species are common in Pennsylvania landscapes. Differences in site preference, flower characteristics, pruning needs, and hardiness exist between the species and sometimes between different cultivars of the same species. Here is a hydrangea primer.

 

Selecting the Right Plant

 

Hydrangea arborescens (Smooth hydrangea)

 

Size: 3-5’ tall

Blooms: Early Summer/white or pink

Exposure: Shade to partial shade

 

A hydrangea native to this region, smooth hydrangea gets white or pink rounded flowers. Smooth hydrangea grows best in partial shade and acidic soil. As exposure to sunlight increases it will require more water.

 

Varieties we grow: Annabelle, Hayes Starburst, Incrediball, Invincibelle Spirit, White Dome

 

Hydrangea macrophylla (Bigleaf hydrangea, Mophead hydrangea, Lacecap hydrangea, Florist hydrangea)

 

Size: 3-5’ tall

Blooms: Summer/blue, pink, or white

Exposure: Partial sun

 

This is the classic plant that many people associate with the name hydrangea. It gets large clusters of blue or pink flowers (white is seen occasionally), which may be rounded or flat-topped depending upon the cultivar. Some cultivars of this species may be marginally hardy in this region. In some cases flower buds may be damaged by winter frosts, preventing the plant from blooming. In the spring this plant is commonly sold as a Mother’s Day plant at grocery stores and other shops. These plants may or may not survive when planted in the landscape. They were produced in a greenhouse and manipulated to bloom early, so they may not survive outdoor conditions. Also, they were not selected for hardiness to this region, so they may never perform well outdoors. To maximize the probability of your plant thriving buy a plant that was raised outdoors and is proven in this region. Hydrangea macrophylla prefers partial shade and does not tolerate dry conditions well. The more sunlight the plant is exposed to the more water it will need.

 

Varieties we grow: Abracadabra Orb, All Summer Beauty, Cityline Mars, Claudie, Let’s Dance Diva, Let’s Dance Moonlight, Let’s Dance Rhapsody Blue, Let’s Dance Starlight, Masja, Parzifal, Shamrock

 

Hydrangea paniculata (Panicle hydrangea)

 

Size: 10-20’ tall

Blooms: Summer/white

Exposure: Sun or partial sun

 

A large plant with showy clusters of predominantly white flowers that may be cone shaped or rounded, panicle hydrangea thrives in the sun as long as it has sufficient water. The flowers may turn pink or red with age. Variation in flower color, shape, and foliage fall color may be observed across cultivars.

 

Varieties we grow: Bobo, Firelight, Limelight, Little Lime, Pee Gee, Pink Diamond, Pinky Winky, Quick Fire, Tardiva

 

Hydrangea quercifolia (Oakleaf hydrangea)

 

Size: 4-8’ tall

Blooms: Summer/white

Exposure: Shade to partial sun

 

Oakleaf hydrangea is native to the eastern United States. It is an excellent landscape plant. It has showy, cone shaped white flowers in the summer. In the fall the foliage turns red or purple. With age the cinnamon colored bark exfoliates and develops interesting textures.

 

Varieties we grow: Little Honey, Pee Wee, Ruby Slippers, Sike’s Dwarf, Snow Queen, Snowflake

 

Hydrangea serrata (Mountain hydrangea, Tea of heaven, Lacecap hydrangea)

 

Size: 2-4’ tall

Blooms: Summer/blue, pink, or white

Exposure: Shade to partial sun

 

This species is very similar to Hydrangea macrophylla. It is slightly more compact in size. The flowers of mountain hydrangea are flat, in a lacecap style. The sterile and fertile florets may be different colors.

 

Varieties we grow: Tiny Tuff Stuff, Tuff Stuff

 

Pruning

 

Hydrangea arborescens: Should be pruned in early spring to approximately twelve inches tall to encourage a compact, upright shape. This should aid in preventing droopy stems once flowering starts.

 

Hydrangea macrophylla: Does not need to be pruned to grow well. Flowers on the growth of the previous season, so early spring pruning will remove the flower buds. Some new cultivars also flower on the growth of the current season, providing a longer display of flowers. If the shape needs to be changed or a few stems removed, they should be pruned in mid-summer.

 

Hydrangea paniculata: Should be pruned in the early spring if shaping is desired. Some cultivars will be less prone to flop if pruned in the spring, other cultivars do not require pruning to remain upright.

 

Hydrangea quercifolia: Usually does not require pruning, though if shaping is desired the best time is late winter or early spring.

 

Hydrangea serrata: Does not require pruning to perform well. If shaping is desired, remove stems immediately after flowering occurs.

 

 

Changing the Color of Hydrangea Flowers

 

Some cultivars of Hydrangea macrophylla and Hydrangea serrata have flowers that may be pink or blue depending on aluminum availability, which is influenced by soil pH. Acidic soil results in blue flowers; alkaline soil results in pink flowers. Use aluminum sulfate (cautiously) to lower soil pH and add aluminum to encourage blue flowers. Use lime or high phosphorus fertilizer to encourage pink flowers.

 

 


 

 


 

Sources: Compiled from experience and information from the Pennsylvania Certified Horticulturist Reference Guide. For more information visit us on the web at www.behmerwald.com www.behmerwald.com