French Hydrangea for Gardens in North and Central Florida1 Gary W
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ENH1069 French Hydrangea for Gardens in North and Central Florida1 Gary W. Knox2 French hydrangea (Hydrangea macrophylla) is a shade- preferring shrub producing ball-shaped or flat clusters of white, pink, blue or purple flowers, depending on soil conditions and cultivar. “Mophead” or “hortensia” hydran- geas (Figure 1) have ball-shaped flower clusters, whereas “lacecap” hydrangeas have flat clusters of tiny, spidery flowers surrounded by a ring of prominent flowers (Figure 2). French hydrangea, also known as bigleaf hydrangea, is the most widely grown species of Hydrangea. Figure 2. The lacecap flower of ‘Mowe’ in its pink form. Origin and Development of French Hydrangea Two forms of Hydrangea macrophylla are native to eastern Asia. Bigleaf hydrangea, Hydrangea macrophylla var. macrophylla, is native to China and coastal areas of Japan. Mountain hydrangea, H. macrophylla var. serrata, is native to China and upland areas of Japan and Korea. Mountain Figure 1. The mophead flower of ‘Decatur Blue’ in its blue form. hydrangea is generally smaller in size and flowers earlier. Some experts consider it more cold-hardy than bigleaf hydrangea. The two natural varieties are otherwise very similar, and both types may produce mophead or lacecap flowers, depending on the selection. 1. This document is ENH1069, one of a series of the Environmental Horticulture Department, UF/IFAS Extension. Original publication date April 2007. Reviewed January 2017. Visit the EDIS website at http://edis.ifas.ufl.edu. 2. Gary W. Knox, Extension specialist and professor, Environmental Horticulture; UF/IFAS North Florida Research and Education Center, Quincy, FL 32351. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office. U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension. French hydrangea has long been valued as a garden plant Growing French Hydrangea in Japan. Hundreds of old cultivars are recorded there, and Japanese breeders continue to develop new forms. When Culture introduced to Europe and the Americas in 1789, these hy- French hydrangea requires shade (either continuous shade drangeas acquired the common name “French hydrangea.” or morning sun and afternoon shade), moist (but not wet) The shrub became hugely popular as a garden and potted soils, and cool winters. Within these environmental criteria, flowering plant in the late 1800s and early 1900s before French hydrangea is adapted to north and central Florida, falling out of favor in the mid 1900s. Today, gardeners and although good site selection and plant care increases in landscapers alike have renewed appreciation of French importance the further south it is planted. After plants are hydrangea because it flowers in shade, often produces blue well established, French hydrangea is moderately drought flowers, and is considered an “heirloom” plant that reminds tolerant and moderately salt tolerant. us of the garden heritage of our forefathers. Description and Growth Habit French hydrangea (Hydrangea macrophylla) is not docu- French hydrangea grows as a mounded or rounded mented in any undisturbed natural areas in Florida. It has shrub composed of stout, upright stems that usually are been evaluated using the IFAS Assessment of the Status unbranched. Leaves are large, often 4 to 8 inches long and of Non-Native Plants in Floridas Natural Areas (Fox et al. 2 to 5 inches wide, and leathery. Leaf color ranges from 2005), is not considered a problem species, and therefore medium to dark green and from dull to glossy, depending may be recommended for use in Florida. on cultivar. Reflowering French Hydrangeas French hydrangea is deciduous in most areas of Florida, The recent discovery and development of reflowering dropping leaves in autumn as days shorten, especially after French hydrangeas revolutionized the market and demand cool weather. However, hydrangea may not drop all leaves for hydrangeas. Reflowering hydrangeas produce an initial in frost-free areas or during mild autumns and winters. In flush of flowers followed by sporadic flowering or later these cases, remaining leaves often fall with onset of new flushes of flowers in the same growing season. Though growth in spring. some older cultivars are considered “free-flowering,” it is French hydrangea is fully cold hardy throughout Florida the newer, “everblooming” cultivars that have been lauded and plants rarely die back. Consequently, French hydrangea and subsequently promoted with elaborate marketing often reaches a mature size of 6 feet tall and wide, and it can campaigns. grow as large as 12 feet tall and wide. When planting French The first everblooming French hydrangea to be recognized hydrangea in the garden, place it in a location providing and commercially promoted was discovered by noted enough space for the plant to mature. Alternatively, use plantsman, Dr. Michael Dirr, in the trial garden of a whole- a cultivar known to mature at a smaller size or plan for sale nursery in Minnesota. One of the nursery employees occasional pruning to reduce plant size. noticed that a neighbor’s French hydrangea flowered late in the year, and he obtained permission to propagate and test Pruning the plant. Dr. Dirr recognized that the plant had value as a Most plants will need little or no pruning unless dieback garden plant along with great commercial potential. This occurs or plants outgrow their preferred size. Prune plants plant was given the cultivar name of ‘Bailmer’ and is now when needed in mid to late summer, removing no more widely known as Endless Summer® hydrangea. than a third to a half of each main stem. Pruning in mid to late summer allows for current year’s flowering as well as Everblooming French hydrangea cultivars provide more sufficient time for some regrowth and for flower buds to garden impact and strengthen the ongoing appreciation of form on the new growth. hydrangea. This revitalized enthusiasm is bringing greater attention to the historic varieties of French hydrangea as Use in the Garden well as inviting efforts to improve hydrangea through new French hydrangea is valued as a garden plant for its ability selection and breeding programs. to flower in shade and for its blue flowers. Sooner or later, most gardens develop areas shaded by trees, house walls or other structures. Shade limits the plants that can be grown in these areas. French hydrangea is well adapted to shaded French Hydrangea for Gardens in North and Central Florida 2 areas, and few other plants can produce as many colorful from buds formed in the tips of stems the previous year flowers under shade. In addition, French hydrangea (on old wood). Most older cultivars bloom just once. Some produces relatively rare and thus highly valued blue flowers French hydrangeas also form flower buds the previous on most Florida soils. year in buds up and down the stems (not just at the tips). These flower buds may develop and flower weeks or months Large leaves and flower clusters lend a coarse textured after the terminal flower buds bloom in early summer. appearance to French hydrangea. Within the environmental French hydrangeas with this pattern of flowering are called constraints of shade and moist soil, French hydrangea can “free-flowering.” be an attractive component of a mixed shrub bed or border where their coarse textured leaves are an effective foil for “Everblooming” hydrangeas produce flowers from buds finer textured plants and where their flower clusters can formed the previous year and also from buds formed on create bursts of color. A mixed bed also will “hide” the new growth. In this latter case, flower buds form in the tips leafless stems in winter, or at least make them less notice- of new growth, and these buds will continue to develop and able. French hydrangea is well suited for use in large massed ultimately flower later in the same year. Technically called beds where their peak flowering in early summer will create “remontant,” French hydrangeas with this characteristic impressive swaths of color. Reflowering types of French have the ability to flower almost continuously throughout hydrangea are especially useful for their showy display of the growing season. Some of these hydrangeas flowered 30 flowers in early summer followed by sporadic flowering weeks or more at the UF/IFAS North Florida Research and throughout the rest of the year. Education Center. Everblooming types of French hydrangea are especially popular and may soon dominate the nursery Conversely, most people may not want to use French trade. hydrangea in a foundation planting because the plant loses its leaves in winter and would thus expose the structure Flower Types behind it. Similarly, it may not be a desirable specimen “Mophead” or “hortensia” type hydrangeas form ball- plant because the winter appearance of the leafless, shaped flower clusters 3 to 8 inches across (Figure 1). Most unbranched stem structure is too open to offer a prominent of these individual flowers are sterile and do not produce profile. Furthermore, the upright, leafless stems create a seed. These sterile flowers are characterized by four wide, more vertical effect rather than the mounded appearance showy petal-like sepals (hereafter called “petals”), each of presented by the fully leafed plant. which may be 1 to 3 inches across. Use in Containers “Lacecap” hydrangeas have flat clusters 3 to 8 inches across French hydrangea has long been used as a small flowering composed of tiny, spidery flowers surrounded by a ring of pot plant that is discarded after flowering.