For a long-lived display of huge showy blooms, few plant families can top the diverse Hydrangea. Every year we see new Hydrangea varieties introduced, making this plant more of a problem-solver and a landscape staple. To choose the right Hydrangea you must first answer two questions: how sunny is my location, and how much room do I have? The answers will lead you to the right Hydrangea family, so then you can choose between the many gorgeous blooms available in that particular family.
To make sense of the huge variety, let’s group the most popular Hydrangeas in six families: large-leaf (macrophylla), serrated-leaf (serrata), smooth-leaf (arborescens), varieties with cone-shaped blooms (paniculata), oak-leaf (quercifolia), and climbing Hydrangea (petiolaris).
The largest and best known group is the macrophylla, or large-leaf. Large-leaf Hydrangeas do best in partial or filtered sun, without protection from hot afternoon sun they’ll wilt and get sunburn. Most large-leaf hydrangeas have large rounded bloom clusters, or “mopheads”. Some, like “Twist ‘n Shout”, are “lacecaps”, large blooms with petals around the edges and delicate pearl-shaped petals in the center, that look like old-fashioned lace doilies.
The introduction of Bailey Nurseries’ “Endless Summer” series revolutionized Hydrangeas by offering plants that bloomed on their new growth each year, guaranteeing continuous bloom. “Endless Summer “Blushing Bride”, “Twist n’ Shout”, and “Bloomstruck” soon followed. Today, all the new large-leaf types bloom on new wood, so you can depend on flowering every year even if plants are cut back or the tips freeze.
Serrata (serrated leaf) Hydrangeas are similar to macrophylla except that they have smaller leaves and blooms and tend to be more compact. Most have lacecap type blooms.
Paniculata, (cone-flowering) Hydrangeas have cone-shaped flower heads that keep expanding, with the new blooms at the tip of the cluster. This extends their bloom, and the flower heads change color over the season. This group of Hydrangeas is less attractive to Japanese beetles than most shrubs. Our favorite is “Limelight”, with immense lime-green flower heads that turn pink and burgundy in fall. “Pinky Winky” is a new introduction that has particularly huge bloom heads. “Quick Fire” is the earliest Hydrangea to bloom each year. Most cone-flowering Hydrangeas grow quite large and need lots of room, and can grow well in full sun.
Smooth-leaf (arborescens) Hydrangeas are classic old-fashioned “snowball” lawn shrubs with heavy flower mops. This family includes “Incrediball”, “Annabelle” and “Invincibelle Spirit”. Most smooth-leaf Hydrangeas will thrive in full sun. “Annabelle” is noted for being very shade-tolerant as well.
Oak-leaf hydrangeas have eye-catching foliage with intense red-purple fall color, and peeling bark similar to that of river birch. These versatile plants do well in shade, so they make a terrific informal hedge or foundation planting where sunlight is scarce. The new “PeeWee” variety fits in smaller spaces. Oak-leaf Hydrangeas are problem-solvers for shady areas, and produce masses of sturdy blooms that can be dried for flower arranging.
Climbing Hydrangeas (petiolaris) look stunning when trained up a stone wall, trellis or fence. They are a problem-solver for narrow beds.
We often get questions about managing Hydrangea bloom color with various soil amendments. In particular, the blue varieties need acid soil or they will bloom pink. We recommend lots of peat moss mixed with your planting soil, since all hydrangeas prefer well-drained acid soil. We use “Holly Tone” fertilizer when we plant Hydrangeas and continue to fertilize every year. Pine bark mulch is much more acid than hardwood, and helps maintain soil acidity over time. Adding garden sulfur, Espoma Soil Acidifier or Miracid will help maintain blue color.
All hydrangeas benefit from being cut back during the winter or early spring. Each place they are cut they will fork and produce more stems, and hence more blooms. Regular shearing to the first bud above last year’s cut makes the plant stronger and gives it a pleasing mounding shape, while also multiplying the number of blooms.
Steve Boehme is a landscape designer/installer specializing in landscape “makeovers”. “Let’s Grow” is published weekly; column archives are on the “Garden Advice” page at www.goodseedfarm.com. For more information is available at www.goodseedfarm.com or call GoodSeed Farm Landscapes at (937) 587-7021.