Unique and with a style all its own, Sky Pencil holly (Ilex crenata ‘Sky Pencil’) is a versatile plant with dozens of uses in the landscape. The first thing you’ll notice is its narrow, columnar shape. If left to grow naturally, it grows no more than 2 feet (61 cm.) wide, and you can prune it to just a foot (31 cm.) in width. It is a cultivar (cultivated variety) of Japanese holly and has evergreen foliage that resembles boxwoods more than hollies. Read on to find out how to plant a Sky Pencil holly and how easy it is to care for this interesting plant.
I. Appearance and Characteristics
Sky Pencil hollies are narrow, columnar shrubs that grow up to 8 feet (2 m.) tall and 2 feet (61 cm.) wide. With pruning, you can maintain them at a height of 6 feet (2 m.) and a width of just 12 inches (31 cm.). They produce small, greenish flowers and female plants produce tiny, black berries, but neither is particularly ornamental. They are grown primarily for their interesting shape.
Sky Pencil holly shrubs grow well in containers. This allows you to use them as architectural plants to frame a door or entryway or on decks and patios. You don’t have to worry about coming in contact with the plant because the leaves aren’t prickly as with other types of holly shrubs.
II. How to Grow and Care
Sunlight
These columnar shrubs prefer full sun, but it helps provide some partial shade from the harsh afternoon sun in warmer climates. Still, the full sun is recommended if you live in a cooler temperature. Your versatile plant needs at least six hours of morning sun daily to encourage healthy foliage.
When the shrub receives little sun, it grows slower, and the branches become less dense.
Temperature & Humidity
Sky Pencil Hollies prefer mild climates as it does not do well in extreme heat or cold. For this reason, it is best to find a spot protecting them from the wind. Furthermore, the plant struggles with high humidity.
When your young plant establishes, it also needs less water as it does have some drought tolerance. For winter care to prevent winter burn and protection against freezing temperatures. You can tie the branches up or use a wrap from the top to the bottom to keep the branches tight.
Alternatively, grow your columnar shrubs in containers to move to a warm spot.
Watering
It would be best if you watered new Holly shrubs often to help the roots establish. Still, it must be moist and not soggy soil, as it increases the risk of fungal infections and root rot. During dry spells, you must water more until the root ball establishes itself.
Another important note, as with most indoor plants, is to leave the soil to dry between watering. Then, for warmer areas, water regularly when you see the soil dry. Finally, if you are concerned that you’re overwatering, keep an eye on the leaves.
The leaves need to be dark green. When the foliage turns lighter, it is a sign of overwatering. A lack of watering will make the leaves turn brown.
Soil
The Sky Pencil grows in different soil types, from sandy and clay to rock. But it is essential to provide the shrub with loose yet loamy soil. So, it needs well-drained soil and helps to add some compost to the mix if the soil is clay or sand.
Another notable thing is that the plant is an all-female cultivar; if you want it to bear fruit, you also need a male variety.
Fertilizing
Usually, your Ilex crenata Sky Pencil does not need feeding when planted in fertile organic soil. All you need to do is add some mulch around the base. But if your plant needs help, you can use an all-purpose, slow-release balanced feed yearly during spring.
After applying the feed, water your shrub well. Still, during the first year, you need not fertilize your new Holly as it does not grow fast during the first year.
You can expect a four to six-inch vertical growth for an established plant. Another important note is to avoid high nitrogen fertilizers forcing your plant to grow. Providing forced growth eventually makes your plant susceptible to diseases.
Pruning and Potting
With your dwarf Japanese Holly varieties, you can grow them in containers. We recommend choosing a pot about eight inches wider than the root ball. Doing this allows your Sky Pencil to grow for the next three years before it needs a bigger container.
Using a Terracotta one as the moisture evaporates faster and will not topple over with your plant’s growth. Also, ensure it has good drainage. Finally, the Sky Pencil Holly will need light pruning to maintain its shape.
The best time to prune is in spring to early fall, but you can do the substantial pruning in early spring before new growth. You can also remove diseased, dead, and damaged branches to promote growth.
It will need a few prunes throughout the growing season to shape your Sky Pencil Hollies in the landscape to form a hedge. If you happen to have an old shrub needing rejuvenation, it helps to cut it back in late winter to 12 inches off the ground.
Propagation
To propagate your Ilex crenata, you can use hardwood cuttings taken in the dormant season. Here are some steps you can follow:
- Cut on one of the canes below a bud union with a sharp, sterilized knife or a pair of pruners. These are small bumps found where the stem and leaf meet. Remove about 3/4 inch of the cutting just above another bud union to end up with a cutting of six inches long.
- Next, remove the leaves and leave two sets at the top.
- Take the cut end, dip it in the rooting hormone, and prepare where you want to grow your cutting. Dig a planting hole and work in coarse sand with compost into the soil.
- Plant your cutting about an inch deep and fill it up while pressing slightly to remove the air pockets; water frequently keeps the soil moist.
- You should notice your cutting developing new growth in spring to show it has rooted.
Another great way to start growing your Sky Pencil Holly is from seed. But you may find your new plant is not true to the parent. Still, germination of the seed can take years and is not recommended.
As with your shrub, it will need well-drained soil with bright light to partial shade to develop.
Pests and Diseases
The Holly can become the home of pests and other problems like strong winds causing damage to the foliage. In addition, a critter like the Holly Leaf Miner female can suck out the fluids of the leaves in late spring. You will notice the leaves turning yellow-brown and will then turn black.
Other insects are whiteflies, spider mites, and scale. Common plant diseases are stem cankers, root rot, and nematodes. Another concern is yellowing leaves from too-alkaline soil, causing an iron deficiency, but it is rare.
To remedy the concern, using a fertilizer made for acid-loving trees and shrubs is best.
III. Uses and Benefits
Unique and with a style all its own, Sky Pencil holly (Ilex crenata ‘Sky Pencil’) is a versatile plant with dozens of uses in the landscape. The first thing you’ll notice is its narrow, columnar shape. If left to grow naturally, it grows no more than 2 feet (61 cm.) wide, and you can prune it to just a foot (31 cm.) in width. It is a cultivar (cultivated variety) of Japanese holly and has evergreen foliage that resembles boxwoods more than hollies. Read on to find out how to plant a Sky Pencil holly and how easy it is to care for this interesting plant.