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Sky Pencil Holly

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Sky Pencil holly gets its name from its narrow shape. As this picture shows, it is tall and skinny.

My shrub in 2011. For a comparison, click "More Images" below to see how much more spindly it was in 2007.

David Beaulieu

Plant Taxonomy of Sky Pencil Holly:

'Sky Pencil' holly has one of those cultivar names that succeeds in being descriptive while also "selling" successfully in a market that craves flashy names. Plant taxonomy lists the genus and species as Ilex crenata.

Plant Type:

Sky Pencil holly is a broadleaf evergreen shrub. A related shrub is Ilex crenata 'Hetzii'. Both are types of Japanese holly, which is valued for its small, tightly-packed leaves; many a casual observer has been duped into thinking these shrubs to be boxwoods, which exhibit a similar foliage.

Characteristics:

Sky Pencil holly is a relatively slow-growing, columnar shrub that reaches 4-10 feet in height, with a width only about 1/3 of that. When my own shrub reached 6 feet tall, its width was only 14 inches at the widest point. The "column" is narrowest at the base, slowly tapering out along the plant's ascent skyward.

These shrubs are dioecious, and you can learn how to tell male and female holly apart. But the male plant needed to pollinate a female does not have to be another Sky Pencil: any type of holly plant will do. The small, greenish-white flowers are unimpressive; but when pollination does occur, a few black berries will be produced (the same color as on Ilex crenata 'Hetzii' and the aptly named "inkberry").

Planting Zones for Sky Pencil Holly:

The parent species, Ilex crenata is indigenous to the Orient. Sky Pencil holly is often listed for planting zones 6-8. I have grown mine successfully in a microclimate (namely, the south side of the house) in zone 5.

Sun and Soil Requirements:

My own Sky Pencil holly has performed well in full sun. But this narrow, columnar shrub is listed as a bush that tolerates shade. It will grow best in a well-drained soil that is allowed neither to become too wet nor too dry. This shrub prefers a soil pH that is acidic.

Uses for Sky Pencil Holly:

There are 2 different ways to build a "privacy fence" using plant material:

  1. Traditional hedges composed of one type of plant, sheared to form a uniform wall
  2. Looser borders, featuring a number of different plants in layers

Sky Pencil holly could work well as a component in the latter. Alternatively, where the goal along a border is simply to provide definition, rather than privacy, a row of Sky Pencils could form an attractive "colonnade" of sorts. The shrub has an interesting enough shape to stand alone and serve as a specimen plant, too.

Personally, I find these shrubs most useful in foundation plantings. Columnar shrubs are often placed strategically at the corners of such planting beds. But a pair of Sky Pencil hollies would also be a logical choice flanking a house entry where the intent is to create symmetry.

Care for Sky Pencil Holly: How to Prune:

Fortunately, this columnar shrub retains its trademark shape without pruning. If you do choose to prune it (for whatever reason), the bush responds well to pruning. For example, mine is planted in a spot where I do not wish it to grow too high. So I periodically trim off excess growth at the top; the plant eventually generates new growth where the trimming took place, prompting me to prune again (and so on). I choose to let my bush get as wide as it wants to, but one could also control the size of a Sky Pencil holly through pruning in this dimension if one wished to.

When I feel like being more meticulous with my pruning, I pinch the tips off of as many branches as I can. This care causes the shrub to become bushier.

If, like me, you wish to grow the shrub in zone 5, my advice would be to mulch it in an attempt to help it through the winter. In summer, mulch will help retain moisture in the soil, which is also important for this shrub. Another item on your winter-care checklist should be to wrap cords around the shrub at strategic points so as to pull the branches into the center; this will avert potential damage due to snow or ice.

Outstanding Features:

As an evergreen, Sky Pencil holly obviously offers winter interest. But this fact only begins to tell the story of its utility in landscape design.

When landscaping for small spaces, a horizontally compact shrub that injects vertical interest into your design can be a real boon -- if you can find one! Sky Pencil holly is one of these rare shrubs. Its columnar plant form is also sometimes called "fastigiate." The Latin fastigium refers to a slope converging with another to form an apex; in the plant world, verticality will be the most noteworthy feature of a specimen said to be "fastigiate."

Many people call this shrub a slow grower. Indeed, in my own experience, it grew slowly the first few years. But for me, the growth rate picked up once the shrub was established. Still, if you need a tall (but not too tall), skinny shrub for a tight spot -- and don't wish to commit yourself to frequent pruning -- this could be the plant for you.

Alternative Columnar Shrubs:

Irish juniper (Juniperus communis 'Stricta') is a needled evergreen shrub that grows to similar dimensions and keeps a columnar form. It's a better choice for gardeners who live where it gets very cold, as it can reputedly survive a winter in zone 3.

There's a barberry shrub that has a columnar form, also. It's called Berberis thunbergii 'Helmond Pillar' and averages 4-5 feet tall by just 1-2 feet wide. Like Sky Pencil holly, this choice is a berry-producer (and being red berries, they are showier). But unlike Ilex crenata, it is deciduous. Grow in zones 4-8.

Another "living column" to consider comes from the yews. But Taxus baccata 'Fastigiata' may be too big at 15-30 feet high by 4-8 feet wide to comfortably occupy that cozy niche you're trying to fill in a small space. Grow in zones 5-8.



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