Tidewater Gardening: February 2006

Winter Berry Color

     One of the many nice aspects of my job here in D.C. is that I get paid to visit the U.S. National Arboretum. As I drove into the parking lot and around the main building the other day, this bright red display of color just stood out. In the circle planting and around the building are plantings of Ilex (serrata x verticillata) ‘Sparkleberry,’ fully loaded with red berries. The visual impact, to me, was quite dramatic. Also included in the plantings were the native Ilex verticillata with a great berry display.
      Ilex verticillata, a.k.a. Winterberry Holly, Common Winterberry, Black Alder, Coralberry and Michigan Holly is one of the parents in the cross that makes up ‘Sparkleberry.’ Ilex verticillata is a deciduous shrub, native to eastern North America, that reaches a maximum height of about 9 feet.
      From late fall through winter, this shrub produces outstanding displays of, for most cultivars, bright red berries which persist on the branches even after the leaves have fallen. The variations between the cultivars are mainly seen as differences in the quantity, size and color of their fruit.
      It is notable that this species is monoecious (plants are either male or female), so berries are only produced on female plants. When planting female selections it is necessary to have a male plant in the same vicinity in order to ensure pollination.
     ‘Jim Dandy’ is a slow-growing, early-flowering dwarf male clone that is useful as a pollinator for early-flowering female clones such as ‘Afterglow,’ ‘Aurantiaca’ and ‘Red Sprite.’ It grows to about 5’ tall.
      There are a number of improved cultivars of Ilex verticillata available in the nursery trade. ‘Afterglow’ is a form that features glossy green leaves that are smaller than typical. It is compact growing (to 10’ tall and wide) with large orange-red berries maturing to orange. It is best pollinated with ‘Jim Dandy.’
     ‘Aurantiaca’ is an unusual form because it produces orange-red fruit that fade to orange-yellow. These fruit are less persistent than most red fruit forms, plus they may discolor easily. It blooms early, this it is best pollinated by ‘Jim Dandy’ or other early-flowering male selections. The habit is around 5’ tall; slightly larger than ‘Red Sprite.’
     ‘Chrysocarpa’ (correctly l.v.f. chrysocarpa) is a naturally-occurring yellow-fruited form. ‘Cacapon’ grows to 5’ tall, possibly more and is similar to ‘Afterglow,’ but more upright in growth. It is heavy-fruiting, with true red fruit, plus the leaves are textured and dark green and glossy. Use ‘Jim Dandy’ as a pollinator.
     ‘Red Sprite’ is a very popular award-winning female clone that matures at only 3’-4’ tall. The habit is pleasantly mounded. Early blooms produce numerous, very large red fruits which persist well into the winter. This USDA release is widely considered to be one of the best winterberries. Use ‘Jim Dandy’ to pollinate.
‘Shortcake’ is similar to ‘Red Sprite’ but larger at 5’ tall with smaller fruit. ‘Southern Gentlemen’ is a late-blooming male pollinator for ‘Winter Red,’ ‘Winter Gold,’ ‘Cacapon,’ ‘Shaver,’ ‘Sparkleberry’ and other late blooming female clones.
      A very unusual and rare form, ‘Sunsplash’ has leaves that are irregularly mottled and marked with yellow. The variegated leaves are complemented by red drupes on this female clone. ‘Winter Gold’ is a branch sport of ‘Winter Red®’ and features unusual pinkish or golden-orange fruit. It grows to around 8’ tall and wide. The blooms come late, so it requires a late-blooming male as a pollinator, such as ‘Southern Gentlemen’. The leaf color is a lighter green that ‘Winter Red®’.
     ‘Winter Red®’ is a popular form that is widely accepted as one of the best winterberries. It forms an upright, rounded shrub to around 8’ tall with dark green foliage. The bright red fruit are borne in profuse quantities and they persist into winter consistently.
      The U.S. National Arboretum’s ‘Sparkleberry’ holly is an improved deciduous holly for the landscape. ‘Sparkleberry’ produces a striking and long-lasting display of brilliant red winter berries on large plants of upright form. Planted at woodland’s edge or in a massed grouping, ‘Sparkleberry’ adds sparkle to an otherwise dull winter landscape. ‘Sparkleberry’ is a female selection and requires a pollinator for good fruiting. A male selection of the same cross, Ilex ‘Apollo,’ was released as a pollinator for ‘Sparkleberry.’
      Released in 1978, ‘Sparkleberry’ and ‘Apollo’ resulted from a National Arboretum plant breeding program to develop hollies with highly ornamental qualities and improved adaptability to diverse landscape conditions. This cross of a Japanese species with a southeastern native resulted in a plant with the heavy fruiting characters of the Asian parent, the larger fruit size and adaptability to wet soils of the native parent, and superior fruit retention to either parent.
      According to the National Arboretum, ‘Sparkleberry’ grows to a mature size of 12 feet tall and wide. It’s growth habit is a large, multi-stemmed, deciduous shrub with an upright form. Its fall foliage color is typical of species, a yellow autumn color. The male pollinator, ‘Apollo,’ is similar in size, habit and leaf. The female selection produces small white flowers in early June. ‘Apollo’ produces abundant flowers. The fruit on the female is abundant, large (5/16 inch), brilliant glossy red with outstanding persistence that may hang until March.
      An advantage to both ‘Sparkleberry’ and ‘Apollo’ is that they are adaptable to wet or dry sites and wide range of soil types from light sandy loam to heavy clay loam and muck soils. This makes them a great candidate for landscapes on the Eastern Shore. The plants are adaptable to sun or shade but the plant flowers and fruits more heavily in full sun. ‘Sparkleberry’ is effective in mass plantings and suitable for large landscape areas. It is also highly ornamental at a woodland edge. This shrub is also tolerant to air pollution.
      There are a couple of other Ilex (serrata x verticillata) crosses that are also worth mentioning. Ilex ‘Autumn Glow’ is a selection out of Rutgers University. This plant is dense-growing to 10’ tall and wide. Its red fruit persist well, but may discolor. Reports vary concerning fall color, which may include yellow and orange shades.
     ‘Bonfire’ is most notable for its profusion of small red fruit early in the season. This selection fruits at an early age and holds the fruit well. It will reach 12’ tall and wide with a mounded habit. ‘Apollo’ should be sued as its pollinator.
      So the next time you are driving around the Eastern Shore and see a bright red display of berries, especially on shrubs in low or wet areas, think Winterberry and how nice the native species or a cross would look in your landscape.
      Happy Gardening!!