If all of this sounds too complicated, there is hope for the hydrangea enthusiast. New cultivars have been introduced in recent years that flower on both old (last season’s) and new (this season’s) stems. These are sometimes referred to as [ever-blooming hydrangeas. They flower almost continuously throughout the season.
These ever-blooming cultivars include: Hydrangea macrophylla ‘All Summer Beauty’, ‘David Ramsey’, ‘Decatur Blue’, Endless Summer®, Mini Penny™, ‘Oak Hill’, and ‘Penny Mac’, Hydrangea serrata ‘Blue Deckle’, and ‘Coerulea Lace’.
Long Blooming Hydrangeas
There are other vigorous old and new cultivars that flower over a very long season. These are sometimes called free-flowering hydrangeas. They include Hydrangea macrophylla ‘Altona’, ‘Ami Pasquier’, ‘Europa’, ‘Forever Pink’, ‘Frillibet’, ‘General Vicomtesse de Vibraye’, ‘Lilacina’, ‘Lanarth White’, ‘Madame Emile Mouillere’, ‘Mousseline’, ‘Nikko Blue’, and Hydrangea serrata ‘Fuji Waterfall’.
Good mountain hydrangea (Hydrangea serrata) cultivars include: ‘Beni-gaku’, ‘Geisha Girl’, ‘Kiyosumisawa’, , ‘Miranda’, ‘Miyama-yae-murasaki’, ‘Tiara’, ‘Woodlander’, and ‘Yae-no-amacha’.
Changing the Color of Hydrangea Flowers
The color of bigleaf hydrangeas is not only determined by cultivar, but also by the amount of aluminum in the soil and the soil pH. The soil pH will determine how available aluminum is to the plant. Acidic soil will give you blue flowers (aluminum available to the plants), and alkaline soil will give you pink flowers (aluminum unavailable to the plants).
To decrease the acidity of your soil (to change flowers from blue to pink), add hydrated lime to your soil in the spring. To increase the acidity of the soil (to change flowers from pink to blue), add aluminum sulfate to your soil in the spring or mulch with oak-leaf mulch.
Other Species of Hydrangea to Grow
Aside from the ever-popular bigleaf and mountain hydrangeas, there is a wonderful selection of other species for the home gardener to choose from. The oak-leaf hydrangea (Hydrangea quercifolia) is slowly becoming a staple of the East coast garden. It is hardy to zone 4. This beautiful south-eastern North American native has ornate peeling bark, large-flowering panicles that age well, and wonderful red fall color. It flowers on old wood and should be pruned immediately after flowering. It is a low-maintenance shrub that needs little pruning; simply remove dead wood and cut back a few stems every few years to maintain a full plant. It thrives in partial shade, but can tolerate quite a bit of sun in this area. Some good cultivars are ‘Alice’, ‘Amethyst’, ‘Pee Wee’, ‘Snow Flake’, and ‘Snow Queen’.
Another hardy hydrangea is the smooth hydrangea (Hydrangea arborescens). An East coast native, this hydrangea does best in partial shade to full sun. It grows from 4 to 6 feet tall and up to 6 feet wide. Smooth hydrangeas flower on new wood. You can treat them just like a perennial and cut them back (either to the ground or back to 1–2 feet) in the fall, or you can leave them for wonderful winter interest and cut them back in the spring. Some popular varieties are ‘Annabelle’, ‘Grandiflora’, and White Dome™.
Panicle hydrangeas (Hydrangea paniculata) have long been a staple of the home garden. They can be grown as a shrub or a small tree. They flower on new wood and can be pruned in the spring according to the desired form. They can be kept small by cutting back to 1–3 feet or allowed to grow much larger. For a small tree, prune the crown of the tree to 3–5 main branches. As with all hydrangeas, remove any weak or dead branches. Panicle hydrangeas tend to flower later in the season than other species. The large-flower panicles can range from white to pale pink to lime green. Cultivars include: ‘Burgundy Lace’, ‘Chantilly Lace’, ‘Grandiflora’, ‘Limelight’, ‘Little Lamb’, ‘Pee Wee’, and the late-flowering ‘Tardiva’.
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