Hydrangeas have become mainstays of late summer and fall gardens. In one nursery catalogue alone, I counted 38 different types of these flowering shrubs. That's a far cry from 1962 when "Annabelle" was introduced and could be seen growing in most gardens. Back then, and even now, when we say "hydrangea" we often think of the large, creamy white blossoms of "Annabelle." Reliable, easy to grow and uncomplicated to prune (cut it down to about 20 centimetres above the ground in spring), "Annabelle" was the popular choice up until about a decade ago when plant breeders developed "Limelight."
"'Limelight' set the standard for all others [that followed]," says Sheridan Nurseries vice-president of nursery sales, Rob Naraj. The size and density of its flowers are what sets it apart, together with stems strong enough to support the large, heavy blooms, which is a really important characteristic to look for in any hydrangea, says Naraj. A large, vigorous shrub that can grow to six or seven feet tall, "Limelight" features huge, long-blooming white-and-lime green flowers.
Of the three main types of hydrangeas now being developed by plant breeders, "Limelight" belongs to the paniculata species, often referred to as PeeGee hydrangeas. One of the hardiest of the three species (zones 3-4), PeeGees bear large, distinctive cone-shaped flower panicles. Others in this category include "Quick Fire" (Hydrangea paniculata "Bulk"), which has attractive red stems and "Tickled Pink," named for its white blossoms blushed with pink. Both are more compact than "Limelight," making them good choices for smaller gardens.
Another of the three categories of hydrangeas is the arborescens species, to which "Annabelle" belongs. Like PeeGees, these are very hardy (zones 3-4). But move over 'Annabelle' and make room for "Incrediball" (H. arborescens "Abetwo"), a new cultivar with massive, mophead-type flowers that bloom in lime green and mellow to white with a touch of lime as the season progresses. It's as easy to care for as its predecessor, too.
One of Naraj's favourite hydrangeas belongs to the third group: bigleaf hydrangeas, or macrophylla species. "Twist-n-Shout" (H. macrophylla "PIIHM-I") has been blooming in my garden for four to eight weeks," says Naraj. But not everyone can grow them. Less cold tolerant, bigleafs are hardy only in zones 5 and 6.
Although hydrangeas tolerate shade, they may take longer to come into bloom in very shady locations, says Naraj. To keep them flowering, apply a slow-release granular fertilizer in early spring.