GARDENING : Salient Points About the Humble Holly : Its many varieties, undemanding nature and ease at which an amateur can create new species make it a growing hobby.
If conifers, rhododendrons and other plants have their champions, so too do the hollies. Making them endearing are their elegance and style, mostly evergreen, and undemanding nature (a few are deciduous), and their suitability to a broad range of landscape situations including background, foundation, specimen and hedge planting.
One of holly’s most vocal supporters is Catherine F. Richardson. Not incidentally, she is secretary of the Holly Society of America, and her love of hollies, moreover, runs deep. Her two-acre yard in the Baltimore suburbs holds 120 kinds, some of them chance crosses she found and introduced herself.
That’s another nice thing about hollies, Richardson says: You don’t need to be a scientist to originate new varieties. Surprisingly, the parents don’t have to be of the same species either, although the chances of success are much greater if they are. Mating requires the presence of a male and a female plant in bloom at the same time and an accommodating bee to enact the pollination.
When the partners are of different species, the offspring are called “interspecific hybrids.” This group is the fastest-growing segment of the holly clan, and its members, because of their exceptional qualities, generate the keenest interest among gardeners. At last count, the number of known species added up to 700.
Richardson says that hollies grow in all parts of the world except Greenland, Iceland, the Arctic and Antarctica. Those that are native to the United States are found on the East Coast.
Classed as major species in the genus Ilex (holly’s botanical name), because they are so widely grown, are American ( Ilex opaca ) , English ( I. aquifolium ) , Chinese ( I. cornuta ) , and Japanese ( I. crenata ) . Their names indicate their localities of origin.
The chief differences between the groups occur in their foliage--its shape, surface quality and number of sharp points or spines--although not every variety conforms to the formula.
In Chinese types, the leaves for the most part are a glossy dark green and are tipped with three spines sharp enough to draw blood. Popular I. cornuta Burford, on the other hand, bears stickers that are fairly benign.
American holly foliage is generally heavily scalloped and spined, its color a duller shade of green. Similar in leaf pattern and thorniness is English holly, but its high luster sets it apart. It’s the choice for decorating at Christmastime.
Japanese hollies have small, rounded, boxwood-like leaves and no spines. This species, moreover, offers a three-foot shrub form (most hollies, not including dwarfs, are tree size) suited to foundation plantings. Unique to Japanese hollies too are their black berries, a departure from the red or yellow fruit usually found.
Although hollies will grow in some degree of shade, which reduces their fullness, they do best in sun. For care, Richardson recommends a once-a-year application toward the end of winter of an all-purpose fertilizer applied at the rate of 1 pound for each inch of the diameter of the trunk. If the application occurs before the last snow, the melting process will carry the fertilizer into the soil. Sprinkle the fertilizer around both sides of the drip line, the circle made by the widest branches. If the soil is sandy or poor, a second dose may be given before July 1. Hollies also benefit from mulching.
When hollies fail to bloom and produce berries, it may be because they lack suitable partners or because the male and female are standing too far apart, because blossoms have been killed by frost, or because bees have been deterred by inclement weather from performing their role.
Varieties Richardson likes especially for gardeners are, for American, Ilex opaca Satyr Hill; for Chinese, I. cornuta Dwarf Burford; for English, I. aquifolium Lewis; and for Japanese, I. crenata Convexa, Heleril or Stokes.
