Hydrangea arborescens 'Ncha4' SWEET ANNABELLE® sevenbark, smooth hydrangea
Hydrangea
The genus Hydrangea comprises about 70 species naturally occurring in Asia and North America. The greatest diversity is found in China and Japan, where hydrangeas have become part of cultural tradition and garden design. The first botanical descriptions date back to the 18th century, when European expeditions brought plants from Japan to botanical gardens in Paris and London. Fossil evidence shows that the genus is several million years old and evolved in the temperate zone of the Northern Hemisphere. Hydrangea arborescens, known as smooth hydrangea, originates from the eastern United States, growing in woodland edges and along streams. Carl Linnaeus described it botanically in 1753. In American culture, it is often planted near country houses and cemeteries, symbolising lasting memory and purity.
Breeding of this species has been carried out since 2006 by Dr Thomas Ranney at North Carolina State University. It all began in the Blue Ridge Mountains, where his student Rich Olsen discovered a rare pink-flowering Hydrangea arborescens, named Wesser Falls. Together they crossed it with the classic white ‘Annabelle’, and after five years, hundreds of trials and more than 1,500 tested plants, they selected a colour-stable and attractive cultivar. In the United States it was introduced as Invincibelle Spirit, while in Europe it became known as Pink Annabelle. Released in 2010, it quickly became not only a horticultural hit but also a symbol of hope – one dollar from each plant sold was donated to breast cancer research. By 2015, when the improved Invincibelle Spirit II was introduced, more than one million dollars had been raised. Other colours and smaller forms followed, such as Ruby Annabelle and Sweet Annabelle.
Sweet Annabelle is the third pink flowering smooth hydrangea bred by Thomas Ranney. Its sterile florets are light pastel pink and form semi-spherical flower heads up to 25–30 cm in diameter – larger than those of Pink or Ruby Annabelle. It usually flowers from mid-June to the end of July, with firm stems that carry even such massive flower heads well. After flowering, the colour shifts into greenish tones and the blooms dry only at the end of summer. Over time it is capable of a natural second flush, though it takes a while. You can speed this up with a simple trick – cut back the whole shrub after the main flowering, feed it generously, and new shoots will grow with fresh blooms that brighten gardens from late summer into mid-autumn.
The leaves are deciduous, broadly ovate to elliptic, with finely serrated margins. They reach about 10–15 cm in length and 6–10 cm in width, giving the shrub a robust look and filling it well. In season they are fresh green, turning yellow in autumn. The plant grows 1 to 1.5 metres tall and wide, forming a dense shrub with firm stems that support the large flower heads well. Compared to the original white Annabelle it appears stronger and more uniform, yet softer and more romantic, while retaining the same reliability and ease of cultivation. US plant patent no. PP28280 was granted in 2017.
Sweet Annabelle is an ideal choice for romantic gardens. With larger and softer pink blooms, it looks more delicate than Ruby Annabelle, making it suitable for both modern and distinctly cottage-style combinations – for example with peonies, viburnums or forsythias to ensure successive flowering from spring to autumn. In a modern design it can be planted next to evergreen shrubs, which soften its tenderness and provide colour without appearing kitschy. Its massive flower heads are lightened by such companions and add airiness to the composition. It fits well into larger borders or as a solitary specimen, where its large pink spheres act as a dominant feature.
Cultivation of smooth hydrangea is straightforward. It thrives in full sun or light partial shade, with enough light to prevent stems from stretching. It tolerates full exposure if watered regularly during dry periods – complete drought is not tolerated as leaves wilt, turn brown and flower heads shrink. Watering is especially important during bud formation. It can withstand short-term waterlogging, but permanently saturated soil is harmful. The soil should be deep, humus-rich and well-drained, and of any pH. Mulching is recommended to keep the soil cool and moist and to protect the roots. Feeding is not essential, but the shrub can be supported after leaf emergence, and again before flowering with a balanced fertiliser low in nitrogen, ideally organic. Pruning is a must here, either in early spring or before winter in mild regions. Since it flowers on new wood, it benefits from deep rejuvenation – cut back up to 80% of the previous year’s growth. It can be grown in containers with regular watering and feeding but performs better in borders. It is neither poisonous nor allergenic and withstands frosts down to –34 °C (USDA zone 4); some sources even report successful cultivation in USDA zone 3, equivalent to –40 °C.
Last update 28-09-2019; 17-11-2025
