Let's face it, gardeners -- hydrangeas are terrific landscape plants. They do have deer issues, don't always bloom reliably, and sometimes the flower color isn't quite what we want. Not to fret -- although the hydrangea breeders haven't yet solved the deer browsing problems, they have introduced some new cultivars that are reliable bloomers/re-bloomers. Depending on the hydrangea species/cultivar (see below), flower color may or may not be impacted by soil pH.
Hydrangea macrophylla cultivars -- Hydrangea macrophylla (Bigleaf hydrangea) is the species that many gardeners have and find that they don't bloom reliably each year. This hydrangea blooms on old (last year's) wood. Assuming that the plant is getting sufficient light and the flower buds are not inadvertently removed by late-season pruning, nonflowering is most likely because the flowers buds are winter killed, and/or the buds survive the winter but are killed by spring cold spells. To circumvent this problem, some new cultivars have been introduced that bloom on old and new wood, thus increasing the odds of consistent flowering.
• 'L. A. Dreamin' 'Lindsey Ann' hydrangea -- In summer, this hydrangea produces mop-head flowers in pink, blue and in-between, regardless of soil pH. The color palette of hues and mixtures is set off beautifully against shiny foliage that is nearly translucent when backlit by light. This compact shrub grows 2 to 3 feet tall and wide and does well in part shade.
• 'Let's Dance Moonlight' -- In summer, this floriferous hydrangea produces large rich rose-pink or blue (depending on soil pH) mop-head flowers that are held on sturdy stems. In autumn, the foliage takes on bronze-red tones for late season interest. This compact shrub grows 2 to 3 feet tall and wide and does well in part shade.
• 'Let's Dance Starlight' -- In contrast to its sister, 'Let's Dance Moonlight,' this hydrangea produces lace-cap flowers, in blue or pink, depending on soil pH. The vivid flower colorations offer a nice contrast with the glossy green leaves. It grows 2 to 3 feet tall and wide and does well in part shade.
• 'Penny Mac' -- In summer, 6- to 8-inch rounded clusters of showy mop-head flowers in blue or pink, depending on soil pH, are formed. This hydrangea can grow 4 to 6 feet tall and 3 to 4 feet wide. It does well in a location with part shade.
• 'Twist-n-Shout' -- This cultivar is the first re-blooming lace-cap from the Endless Summer Collection. It's a re-bloomer that produces exquisite blue or pink (depending on soil pH) flowers during the summer. An added bonus to the flowers is the burgundy-red coloration of the foliage in the fall. Shrub grows 3 to 5 feet tall and wide and does well in part shade.
Hydrangea paniculata cultivars -- The common name, panicled hydrangea, describes the large cone-shaped flowers that appear in midsummer. Since this hydrangea species flowers on new (current year's) wood, it blooms reliably every year. Depending upon the cultivar, this hydrangea can reach a height of 8 to 20 feet and be grown as a multistem shrub or a single trunk tree.
• 'Kyushu' -- This cultivar can grow 8 feet tall and wide. In midsummer, the lush, bright green foliage is topped with white flowers (8 inches plus) that turn pinkish to almost purple as the season progresses. This cultivar holds its blooms later than many other hydrangeas. It does well in sun to part shade.
• 'Little Lime' -- This unusual, compact cultivar grows 3 to 5 feet tall and wide. In midsummer, the dark green leaves are topped with 6- to 8-inch lime-green flowers that take on hints of pink and red as they mature. The flower color is not affected by soil pH. This hydrangea does well in sun to part shade.
• 'Quick Fire' -- This beautiful hydrangea is a breakthrough, because it flowers about a month earlier than other H. paniculata cultivars. In mid-summer, creamy-white flowers form on red stems, and as the season progresses, the flowers take on a deep rosy-pink coloration. Flower color is not affected by soil pH. This shrub can grow 6 to 8 feet tall and wide and does well in sun to part shade.
• 'Vanilla Strawberry' -- A relative of the PeeGee Hydrangea, it forms large flowers in midsummer. The flower coloration begins as creamy-white, changes to pink, and then eventually becomes strawberry-red to burgundy. As the summer progresses, new flower heads continue opening, and as a result, the plant displays all three color stages at any one time. The multicolored blooms, which are borne on red stems and contrasted against the green leaves, make a spectacular sight. This shrub grows 6 to 8 feet tall and 4 to 5 feet wide and does well in sun to part shade.
• Hydrangeas do best in soils that are organically rich, moist, well-drained and acidic.
• Fertilize plants with an organic fertilizer, such as Espoma Holly-tone (4-3-4), per label recommendations.
• Pruning of young Hydrangea macrophylla and paniculata cultivars should be limited to the removal of dead branches. Let the plants mature before considering more extensive pruning.
• Changing flower color (where it can be changed) may be a difficult challenge because it depends on the hydrangea's genetics and the environmental conditions above and below ground. The final flower color will ultimately be the hydrangea's decision, not yours.
• For blue flowers (soil pH should be 5.0-5.5), dissolve one tablespoon of aluminum sulfate in a gallon of water and drench the soil around the plant in March, April and May. Don't overdo this treatment, because too much aluminum can be toxic to the plant's root system.
• For pink flowers (soil pH should be 6.0), dissolve one tablespoon of hydrated lime in a gallon of water and drench the soil around the plant in March, April and May.garden
Steve Piskor is a Penn State master gardener and Pennsylvania certified horticulturist. Columns by master gardeners will sometimes appear in place of the Garden Q&A by Sandy Feather, a Penn State Extension educator.