Growing Beautiful Boxwood Shrubs

Zones:

5 to 9 for most, with a few varieties hardy to Zone 4.

Height/Spread:

Ranges from 1 to 20 feet tall, 2 to 8 feet wide.

Exposure:

They prefer partial or dappled shade, but can tolerate full sun — short of scorching mid-day sun. Overexposure to sun causes burning and bronzing of foliage. If planting in a brighter location, look for varieties that may be more tolerant of sun, such as ‘Morris Midget’.

Bloom time:

Small, insignificant, yellow-green flowers bloom in spring.

Color and characteristics:

Mainly grown for their foliage; their leaves grow opposite, are lance-shaped to almost rounded, and are leathery to the touch. Many have darker blue-green foliage, others a paler green, and some have variegated leaves.

Toxicity:

Boxwoods contain an alkaloid that is toxic to dogs, cats and horses, as well as humans. Contact with the sap can cause skin irritation, and ingestion of the leaves can trigger intestinal distress, dizziness, convulsions and respiratory failure. See more Common Poisonous Plants for Dogs and Cats.

When to plant:

Plant in fall or late winter to early spring.

Where to plant:

Different varieties have different needs, mainly with regard to exposure and cold hardiness, so plant them in a location that is appropriate for that particular variety. One thing they all have in common is that they don’t tolerate standing water or soggy soil, so make sure the area drains well. The most common problem is bronzing — damage to the foliage from too much sun or wind exposure, causing it to turn yellow-orange or reddish-brown. To keep them healthy and looking their best, provide protection from winter wind and summer sun, and avoid planting in southwestern exposures.

How to plant:

The planting hole should allow the crown of the plant to sit slightly higher than soil level. Mound up soil to the base to keep water from pooling. If planted too deeply, they can become stressed and die.

Photo by: Mykhailo Pavlenko / Shutterstock.

Pruning boxwood:

Trimming or shearing encourages new growth and is best done in late spring or summer. Avoid pruning or trimming in fall or winter, because the new growth can be too tender to handle frost. When cutting back, don’t overdo it, as this can produce too much growth. While a nice, compact bush may look healthy on the outside, that dense outer foliage can keep air and light from getting to the inner part of the plant. Dead leaves and stems can also build up and harbor fungal diseases. Thin the outer growth annually so that air and light can get in, and prune away any dead or diseased branches from the center of the plant. Shearing can be done with hand pruners, hedge clippers or electric trimmers.

Winter care:

Help them get through the winter by providing some extra protection from cold temperatures and winds with burlap wraps, decorative protection, or a windbreak. Surrounding them with a good layer of mulch will keep the roots insulated and conserve moisture to prevent dehydration damage from cold winter winds. If bronzing of the foliage does occur, resist the temptation to cut it back immediately. The new growth that is prompted from cutting won’t be any hardier than what was damaged, so hold off until spring when new growth can make a comeback.

Soil:

Boxwoods are extremely flexible and can adapt to various types of soil — provided it drains well. Ideal soil pH is 6.5 to 7. For more on proper soil preparation and how to adjust your pH if needed, read Garden Soil 101.

Amendments & fertilizer:

Apply a balanced all-purpose fertilizer in spring to promote foliage growth, and again in fall to encourage root growth. Apply the fertilizer throughout the root zone, which extends beyond the crown of the plant. Be careful; their shallow root systems can be damaged by over fertilizing.

Watering:

Newly planted shrubs will need regular watering for the first year, especially during hot, dry weather. In their second year, root systems are still developing, so continue to water regularly if rainfall isn’t enough. Once established, they’re quite drought tolerant and only need extra watering during dry spells. Water at the base of the plant to keep the foliage dry and conserve moisture with a layer of mulch that extends 12 to 15 inches past the foliage line.

Diseases and pests:

Boxwood leaf miners, scale insects, lesion nematodes, caterpillars and mites can be a problem; treat with organic neem oil or insecticidal spray. They can also be susceptible to powdery mildew, Pythium root rot, canker and leaf spots. Boxwood blight is a serious problem in many states. See below for more information and planting alternatives.

Deer resistance:

A useful part of a deer-resistant garden, as the same alkaloid that makes them toxic also makes them distasteful and can give off a pungent scent, deterring deer.

With so many sizes, growth rates and habits it can be tough to decide which one is best. Here are a few recommendations:

For topiaries and globes, groundcover, or rock gardens dwarf English boxwoods work well because their dense form and slow growth rate mean less pruning and maintenance. Fast-growers aren’t the best choice for complex topiaries as they may outgrow their shape quickly and need continual upkeep. (Staff picks: Buxus sempervirens North Star®, B. sempervirens 'Suffruticosa' and B. ‘Green Velvet’)

For hedges and edging that will fill in quickly, use moderate to fast-growing varieties and plant at half the distance recommended. (Staff picks: Buxus microphylla Sprinter®, B. microphylla var. japonica ‘Green Beauty’ and B. sinica var. insularis ‘Winter Gem’)

For spirals and cones use taller, more vigorous plants that have a naturally conical or columnar shape. (Staff picks: Buxus ‘Green Mountain’ and B. Green Tower)

For colder zones: Korean boxwoods (B. sinicas var. insularis) survive well in lower temperatures, making them the best choice for cold climate gardens.

Photo by: Lee Snider Photo Images / Shutterstock.

One of the most versatile plants in any landscape, the opportunities to use them are nearly endless. Here are a few ideas to get you started:

• Create a border along a property line, walkway or garden bed.
• Cover up unsightly foundation lines.
• Add structured elements to an otherwise natural-style or informal garden.
• Define outdoor spaces with low or medium boxwood hedges.
• Excellent choice for year-round container displays.
• Accentuate entrances, driveways or gateways with manicured specimens.
• Add curve-appeal with clipped spheres in square beds.
• Add some whimsy to your garden, patio or porch with a fun topiary shape.
• Plant with companions such as spirea, maiden grass, coneflower, liatris, Oso Easy® roses, rhododendrons and peonies.

Leaves affected by boxwood blight. Photo Courtesy of A. Windham / University of Tennessee.

What is boxwood blight?

Boxwood blight is a fungal disease that affects the leaves and branches of boxwood plants. First reported in the United States in 2011, it has now been detected in 27 states and continues to spread.

What are the signs of boxwood blight?

One of the first signs is light to dark brown circles with darker borders on the leaves. Plants drop their leaves quickly after being infected, so this stage is often missed. Dark brown to black streaks may also appear on stems.

Does boxwood blight kill boxwoods?

The disease doesn’t directly affect the roots, so plants may grow back. However, boxwood blight weakens plants and makes them susceptible to other pests and diseases. It is these secondary infestations and infections that usually kill the plants.

What should I plant instead if blight is a problem in my area?

If you live in an area that is affected, Gem Box® and Strongbox® inkberry hollies can be great boxwood alternatives. Both are native evergreens that grow similarly in size, shape, and texture, and provide better resistance to disease and winter damage.