New hydrangeas: Are they outstanding or overhyped?

Hydrangeas have exploded on the nursery scene. Marketing campaigns and promotions of new cultivars of Hydrangea macrophylla appear almost daily, or at least it seems that way. Some are overseas-bred plants repackaged or renamed for release here while others are new hybrids by homegrown breeders. Can we believe all the marketing hype about new hydrangeas? Which of them will hold up throughout the diverse rainfall, heat and humidity associated with USDA Hardiness Zones 6-9, the range of Hydrangea macrophylla in North America?

The answers to these questions lie in unbiased, side-by-side comparisons in regions throughout the United States. I believe it is far better for growers to find these answers proactively than to wait for consumers to weigh in -- by scooping up some selections and slamming others.

University trial gardens can be part of this solution. The table below reports on side-by-side evaluations at the University of Florida/IFAS North Florida Research and Education Center located in the Gulf Coast region (Zone 8b). We have been tracking hydrangea budbreak, flowering and growth for several years, adding cultivars as they become available.

We have 31 cultivars under evaluation with an additional 16 cultivars represented by only one or two plants. Cultivars are screened for flowering, growth, pest susceptibility, maintenance needs and overall adaptability. The planting emphasizes newer and reflowering cultivars as compared to a few older selections. Hydrangeas are not deadheaded, so this planting offers a true test of cultivars’ reflowering abilities.

Hydrangeas already were experiencing renewed interest from gardeners during the late 1990s because of their old-time charm, shade adaptability and fabulous blue flowers. The 2003 introduction of the reflowering Endless Summer -- and its wildly successful marketing campaign -- incited gardeners into a frenzy rarely seen.

Many nurseries and breeders took note of the resulting sales of Endless Summer, leading in turn to the recent explosion of new cultivars and marketing campaigns. Are these new hydrangeas a boon for growers and gardeners or just a series of disappointing, endless choices that go on forever and ever?

Hydrangea: The next generation

Reflowering hydrangea truly is a new paradigm in the world of hydrangea, or at least new to most growers and the general public. Hydrangea aficionados had long valued the reflowering characteristics of old cultivars like ‘Mme. Emile Moulliere.’ It took the discovery of Endless Summer and its relentless marketing campaign to raise awareness of this class and grab the attention of growers and the gardening public alike.

In our planting in North Florida, Endless Summer and its cohort of mophead reflowerers hold up to the marketing hype. Established plants of Penny Mac, ‘Decatur Blue,’ ‘Oak Hill,’ ‘David Ramsey’ and Endless Summer annually provide 17-36 weeks of flowering. In contrast, cultivars not considered reflowering provide less than half of this amount of flowering.

One progeny of Endless Summer, Blushing Bride, also is an outstanding performer. Blushing Bride has white mophead flowers tinged blue or pink, depending on soil pH and aluminum availability. These attractive, vigorous plants flowered up to 35 weeks per year in our trial. In contrast, Mini Penny, a descendent of Penny Mac, only flowered up to 13 weeks here, not as extensively as marketed. Mini Penny boasts a compact or dwarf plant form, but this trait may also relate to lower vigor, at least in our experience so far.

Other notable long-flowerers include ‘Fuji Waterfall,’ a beautiful white-flowering lacecap producing double florets that cascade outward from the inflorescence. ‘Fuji Waterfall’ flowers up to 34 weeks, though these lacecap flowers admittedly aren’t as showy as mophead types.

New old-school hydrangeas

With all of the gardening excitement about hydrangeas, some companies are introducing and promoting non-reflowering hydrangeas. New releases such as Queen of Pearls and Princess Lace are fine plants, but provided only up to 14 weeks of flowering. ‘Lady In Red’ and Midnight Duchess are notable for having red- and black-colored stems, but flowering only lasted up to 10 weeks for ‘Lady In Red’ and up to nine weeks for Midnight Duchess.

Other cultivars have amazing flower forms but are not reflowering. ‘Shamrock’ has pink to purple lacecap flowers with fabulous large, double florets. After 1 1/2 years of establishment, it flowered up to eight weeks. ‘Miyama-yae-Murasaki,’ sometimes called ‘Purple Tiers,’ has similar double florets in shades of pink to purple. So far this plant is less vigorous than ‘Shamrock’ and has flowered only up to two weeks. Some cultivars may need more than two years of establishment before reaching their stride, while others may not be adapted to this region.

More bang for the buck

There’s more to some cultivars than the flowers. Midnight Duchess has black stems and ‘Lady In Red’ has red stems and fall color. More significantly, aging flowers of some cultivars don’t immediately turn brown, and instead morph into beautiful, burgundy-hued inflorescences. These pale- to deep-burgundy, aged flowers extend the season of flower color for many weeks. The best, most outstanding example is Blushing Bride. Its aging flowers became a beautiful burgundy, lasting up to 11 weeks before finally turning brown. Other cultivars exhibiting a lesser degree of ornamental fading flowers are Endless Summer, Penny Mac, ‘Oak Hill,’ ‘David Ramsey,’ ‘Decatur Blue’ and Mini Penny.

Future forward

The evaluation planting in North Florida has a long future ahead. Recent introductions such as Color Fantasy, Bits of Lace, ‘You Me Romance,’ Big Daddy, Lemon Daddy, the Mystical series and others are planted but have not been evaluated long enough yet. New hydrangeas continue to be released.

More importantly, is there room in the market for all of these new hydrangeas? Will consumers buy non-reflowerers, become disappointed in one-season bloom and turn away in disgust, ruining the market for all hydrangeas? Stay tuned: the jury still is out on this.

I believe the future of hydrangeas lies with reflowering types. Many non-reflowering hydrangeas will be valued by collectors or garden enthusiasts. However, the mass market is aware of and excited by Endless Summer and others like it, and any performance less than reflowering will likely be ignored by the general consumer.

- Gary W. Knox

Gary W. Knox is an extension specialist and professor of environmental horticulture at the University of Florida/IFAS North Florida Research and Education Center in Quincy, gwknox@ufl.edu.

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June 2008