Winterberry (Ilex verticillata) is a deciduous native shrub that grows from 6 to 15 feet high and nearly equally broad. It’s hardy in U.S. Department of Agriculture hardiness zones 3 through 9 and thrives in sun to partial shade. Although winterberry loses its 1- to 3-inch green leaves in the autumn, it’s prized for its bright red berries that stay on the bare stems. Given the space it needs to develop, it partners well with a number of other plants.
Pollination
The most significant plant to develop having a winterberry holly is just a winterberry of their opposite sex. Berries are produced on female plants, but pollen from a nearby male plant is vital for the fruit formation procedure. Plant tags often carry information regarding great pollinators for a particular selection. For example, the male number “Southern Gentleman” is a suitable pollinator for female varieties including “Cacapon,” “Shaver” and “Sparkleberry.” “Red Sprite,” a compact, 3- to 4-foot selection, can be pollinated by the male “Jim Dandy.”
Shrub Companions
Tall varieties, such as “Winter Red” and “Jolly Red,” belong at the rear of the edge. Since winterberry is deciduous, companion plantings should incorporate some evergreens for construction. Another holly variety, “Sky Pencil” Japanese holly (Ilex crenata “Sky Pencil”) is evergreen, hardy in zones 6 through 8 and also comes with a columnar shape that makes contrast. For the front of a mixed shrub or shrub/perennial/annual border, the evergreen boxwood “Green Gem” may work. It’s hardy in zones 4 through 9, rises 1.5 to 2 feet tall with an equal spread and is easily clipped to shape.
Perennial Companions
Winterberry pairs well with perennials that like the same sunny or lightly shaded conditions with somewhat moist soil. A mixed planting of daffodils (Narcissus) and daylilies (Hemerocallis) may provide long spans of attention from spring through early to midsummer. Both are usually hardy in zones 3 through 9 or 10. Garden stalwarts such as tickseed (Coreopsis), coneflower (Echinacea) and asters (Aster and Symphiotrichum) create suitable companion plants during summer and into autumn. Many tickseed and coneflower varieties are hardy in zones 4 through 9, and many asters are hardy in zones 4 through 8.
Grasses
Grasses can be companions to winterberry. Striped eulalia (Miscanthus sinensis “Variegatus”) is a tall grass, with feathery seedheads that persist throughout the winter. It’s hardy in zones 5 through 9. Purple moor grass (Molinia caerulea subsp. Arundinacea), also hardy in zones 5 through 9, features purple-green summer flowerheads and yellow fall foliage. Slightly shorter, at about 3 ft, is fountain grass (Pennisetum alopecuroides), with narrow, arching leaves and purplish, bottlebrush-like flower panicles. It’s hardy in zones 6 through 9.