Ithaca Journal Article: A Sampler of New Flowering Shrubs

A Sampler of New Flowering Shrubs
By Mary Hirshfeld

In recent years, gardening has become so popular that it is now profitable for nurseries, individuals, and experiment stations to undertake the time, expense, and risk involved in developing new varieties. Plant variety protection legislation, patent laws, and trademark rights are allowing breeders to recoup the often extensive costs involved in breeding and selecting new cultivars. The diversity of choices available among ornamental plants is expanding at an astonishing rate.

One previously overlooked area that is now rapidly gaining ground is the development of new varieties of flowering shrubs. These varieties expand our choices of plant size, flower color and form, hardiness, and disease resistance. Indeed, the choices available are increasing so quickly that the shrub collection at Plantations has been expanded this year to accomodate as many new varieties as our climate and site conditions will permit.

Shrubs have traditionally been selected for their flowering characteristics and, to a lesser extent, for their fruit displays. A number of new shrub introductions offer attractive, colorful foliage that creates the possibility of using them in new ways. Forsythia x intermedia is a good example of how shrubs are changing in previously unimagined ways. Until recently, all forsythia breeding focused on improving flower-bud hardiness, ignoring plant habit and foliage quality. The result were forsythias that overcame the snow-line effect (where flower buds above the insulating snow were killed by cold winter temperatures, but retained their bland green foliage and large, ungainly growth habit). Forsythias 'New Hampshire Gold', 'Meadowlark, and 'Northern Gold' do indeed offer hardy flower buds but they retain the large size and gawky habit of their predecessors, growing long canes at awkward and unruly angles. More recently, breeders have begun to scale down plant size and tame growth habit to produce a smaller, more graceful shrub. From France comes a series of very low growers all with cultivar names that include "Court", such as 'Courtasol', or 'Courtacour', but are more frequently sold under their trademark names of 'Golden Peep', 'Goldilocks', and 'Gold Tide'. All mature at under 3 feet, and are covered head to toe in flowers in early spring. Of the three, 'Gold Tide' is the least showy in flower, although it has attractive foliage and a spreading, slightly arching habit that makes it an ideal groundcover plant. These smaller forsythias also sell well because they look very appealing in containers, both in and out of flower, whereas the taller selections look really ungainly when out of flower, and if they don't sell in spring, they will not sell at all. Another wonderful new forsythia is 'Fiesta', with bright gold leaves edged in green and a reddish tinge to the new stems. The gold remains clear and strong and does not leach out in full sun. 'Fiesta' originated with Duncan and Davies nursery in New Zealand and has been available to American gardeners for several years. The plants we have here at Plantations have remained very compact and have not exceeded 3.5 feet in height, although I have seen some nurseries describe this as reaching 5 to 8 feet in height. Others say it tops out at 3 feet, so there is some confusion about what 'Fiesta' will mature into with age. Another selection that will be arriving at Plantations this spring is 'Kumson', a selection of the Korean forsythia (Forsythia viridissima var. koreana) selected for its unusually patterned leaves, traced with white veins against a bright green surface.

Old fashioned weigela (Weigela florida) is another shrub that is still dismissed as having only one season of interest that should be hidden away when it is not in flower because of its drab foliage and graceless habit. However, both Canadian and French plant breeders have taken an interest in working with weigela, and new selections offer colorful foliage, a wider and clearer range of flower colors, and improved, more compact habit. 'Red Prince' and 'White Prince' are two introductions from Iowa State University that have the typical upright-arching habit of the species and can reach 5 feet in height. Both have the floriferousness so valued in the species and in May are draped with clusters of tubular flowers in bright red or clear white. Foliage quality on both is exceptional, their thick dark green leaves providing a wonderful foil for the flowers. The Dancer Series, selected by Felicitas Svejda of Ag-Canada for compact habit and improved flower color, offers a nice array of flower colors on shrubs scaled down to meet the needs of today's smaller gardens. Look for 'Rumba', 'Polka', 'Minuet', and 'Samba'. The hardiest of these are 'Samba' at 2 to 3 feet in height, with red flowers and dark green foliage edged in purple, and 'Polka', an extremely floriferous pink selection that reaches 4 to 5 feet in height. Two weigelas offer dark purple foliage that is a great improvement over the dirty brown leaves of 'Java Red'. Both are of Dutch origin, and were selected by Herman Geers. 'Alexandra', trademarked as 'Wine and Roses', reaches standard weigela height and displays pink flowers against rich purple leaves. It is a recipient of the Pennsylvania Horticultural Society's Gold Medal, which recognizes landscape plants of outstanding merit. 'Elvera', trademarked as 'Midnight Wine', is a diminutive version of 'Wine and Roses' that reaches only 2 feet in height and makes a nice addition to plantings of herbaceous perennials or annuals.

The elderberries, previously grown sparingly for their edible fruit, have been transformed into gorgeous foliage plants that can be used with other shrubs. And when coppiced, or cut to the ground each spring to keep their height down, they make nice additions to a perennial or annual planting. The black-fruited European elder (Sambucus nigra), offers the widest number of variants. All have proven to be highly adaptable to soil conditions here at Plantations, tolerating both dry and wet sites in sun and shade, although they are at their most luxurious in rich, constantly moist soil with just a touch of shade. There are many purple-leaved variants of S. nigra that are indistinguishable from one another, yet have appeared under a number of different names such as 'Purpurea', 'Foliis Purpurea', and 'Porphyrifolia', all of which have now been collected under the umbrella of the name 'Guincho Purple'. This is indeed a striking plant with deep reddish-purple foliage and lovely platters of cream flowers tinted with pink. Sambucus nigra 'Gerda', trademarked as 'Black Beauty', is an improved version with rich dark purple foliage that has just arrived from England. It was developed by plant breeders working at the Horticultural Research Institute associated with the East Malling Research Station in England, and has been a raving success since its introduction to European markets in 2000. At the other end of the color spectrum is S. nigra 'Pulverulenta', with its striking albino foliage. Its pale green leaves are so densely spotted with cream, white and pink that little green is visible, and the lack of chlorophyll results in a slow-growing plant that is best sheltered from the strong afternoon sunlight. A bright gold-leaved variant that brightens up a shaded nook is 'Madonna', whose foliage is marbled with tones of green and yellow. This has not proven rambunctiously vigorous at Plantations; it has remained around 4 feet tall and has not needed coppicing to keep it in bounds. Finally, for fans of interesting foliage, 'Linearis' is an excellent choice, its thread-like finely divided foliage offering a delicate ferny texture that sets off the bolder purple-leaved forms well.

Selections of the bigleaf hydrangea (Hydrangea macrophylla) that can be enjoyed for their foliage alone are useful additions to our Ithaca gardens, where most winters kill back the flowering wood, leaving luxurious foliage that returns on new growth--but without blooms. Hydrangea macrophylla selections are traditionally divided into two categories, based on the structure of their flower heads. The lace-cap types have flower heads characterized by a central dome of tiny fertile florets encircled by large showy sterile florets producing a delicate airy effect. The hortensia types, aptly known as "mop heads," have a large congested globular flower head that often bends stems down with their weight. Cultivars of both flower types abound, and when grown in a protected site in zone 5, or better yet zone 6, all are indeed lovely midsummer blooming shrubs. For those if us in zone 5 that do not have a protected site, several of these make lovely foliage plants. 'Variegata' produces lush mid-green leaves decorated with a crisp white edge and it will produce the occasional lavender lace-cap flower head. 'Lemon Wave' is a real looker, with leaves irregularly colored with yellow, cream, white, and green. One nursery catalog aptly describes this as having "mauve lace-cap flowers if you live in a mild climate, but who cares?" Both of these are best grown in a lightly shaded spot to prevent the leaves from drooping in the high heat of mid-day. 'Ayesha' is a mop head with arresting thick, dark green foliage of tropical dimensions. One year it even managed to produce one small globular flower head, that remained eclipsed by the fantastic foliage. It dies reliably to ground level every winter and rebounds in spring with thick sturdy stems draped with gorgeous leaves. A tiny moppette that remains beneath the snow line and thus does flower annually is 'Winning Edge'. This rarely exceeds 12 inches in height, making it a worthwhile compliment to herbaceous perennials or ferns, and covers itself throughout the summer with diminutive mop heads of pink flowers. When you visit Plantations, look for hydrangeas in cool shaded nooks in the rhododendron collection and search out elderberries, weigelas, and forsythias in the sun-drenched beds of the shrub collection.