Plant Profile: Inkberry (Ilex Gabra)

Image of inkberry holly. This shrub isn't beautiful, but it's practical.
David Beaulieu

Inkberry holly is a slow-growing broadleaf evergreen shrub with a rounded-to-upright growth habit. It is easy to grow and offers good winter color. It is a popular choice for areas with damp soil, such as woodland gardens and plantings around bogs and ponds.

Description

Inkberry is a native form of evergreen holly with an upward, clumping form. The native species grows 5 to 8 feet in height and spread, although several cultivars have a more compact, smaller form. It has glossy dark green leaves, oval to elliptical in shape, that are about 1 1/2 inches long. The leaves are retained in winter unless temperatures fall well below zero. Insignificant greenish-white flowers appear in May and June, giving way to pea-sized black fruits that mature by early fall.

Botanical Information

Native to the eastern U.S., inkberry is hardy in zones 4 to 9. In native locations, it prefers sandy, acidic woodland soils and is often found along the edges of swamps and bogs. Inkberries are dioecious (separate male and female plants), so female plants need a male plant to pollinate them if the berry-like fruits are desired.

The native form of inkberry is somewhat shaggy and leggy and tends to spread by suckering, so landscape plantings tend to use one of several cultivars that have better form and better behavior.

The name "inkberry" is a clear reference to the fruits produced by the shrub, as is the plant's secondary common name, "gallberry." This alternate name derives from the fact that black ink was once made from the galls of oaks.

The taxonomical name, Ilex gabra, features the genus name Ilex, meaning "oak." This is probably a reference to the similarity of the leaves to those of the holly oak (Quercus ilex). The species epithet, gabra, means "smooth," referring to the plant's smooth leaves, which are quite different than the prickly leaves of more common hollies.

Landscape Uses

The species form of inkberry is favored by native plant enthusiasts, but most landscape planting features one of the cultivars. Inkberry shrubs work well massed or grouped for shrub borders and are also used in foundation plantings or for low, informal hedges. Inkberry works well in moist locations, such as woodland gardens are around landscape ponds and water features.

Inkberry shrubs hold up well to polluted urban conditions. Bees are fond of the flowers, and the resulting honey has a highly prized, unique flavor. Inkberry is sometimes planted as a source of food for bee hives. Wild birds are also drawn to inkberry.

Inkberry is resistant to deer, and thus is a good choice in areas where browsing deer are a problem for other shrubs.

Growing Inkberry

Inkberries are dioecious (meaning there are separate male and female plants). Female plants need a male pollinator if you want them to produce the berry-like fruits. A single male plant is usually all that is required.

Inkberry is best planted in average, medium to wet soils and in full sun to part shade. It is adaptable to both light and heavy soils but does best in rich, consistently moist, acidic soils. It does not do well in alkaline soils. Fertilize in spring with a fertilizer such as Holly-Tone.

Pruning should be done in early spring just before new growth emerges, but pruning needs are minimal unless you are using the shrubs in a hedge. Remove root suckers regularly if you don't want the shrubs to colonize and spread.

Recommended Cultivars

  • 'Densa' grows to 3 to 4 feet in height with a slightly greater width.
  • 'Compacta' grows to 3 to 4 feet in height with a spread up to 6 feet. It has tighter, more rounded growth habit than other forms.
  • 'Shamrock' grows to 4 feet in height and spread. It has bright green foliage and is known to sucker less than other varieties.

Problems

Inkberry is a very easy-to-grow plant with few serious insect or disease problems. Leaf spot is an occasional problem. Spider mites sometimes appear, especially in dry conditions. The shrubs are also susceptible to chlorosis (yellowing of the leaves) if they are planted in high pH alkaline soil.