Growing Beautiful Boxwood Shrubs

Photo by: Lee Snider Photo Images / Shutterstock.

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:

Boxwoods 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:

Boxwoods are mainly grown for their foliage. Their leaves grow opposite, are lance-shaped to almost rounded, and are leathery to the touch. Many boxwoods 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.

When to plant:

Boxwoods can be planted in fall or late winter to early spring.

Where to plant:

Different boxwood 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 with boxwoods is bronzing — damage to the foliage from too much sun or wind exposure, causing it to turn yellow-orange or reddish-brown. To keep boxwoods 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 boxwood plant to sit slightly higher than soil level. Mound up soil to the base to keep water from pooling. Boxwoods that are planted too deeply can become stressed and die.

Photo by: Mykhailo Pavlenko / Shutterstock.

Pruning boxwood:

Trimming or shearing boxwoods encourages new growth and is best done in late spring or summer. Avoid pruning or trimming boxwoods in fall or winter, because the new growth can be too tender to handle frost. When cutting your boxwoods back, don’t overdo it, as this can produce too much growth. While a nice, compact boxwood 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.

Boxwoods in winter:

Help your boxwoods 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, boxwoods’ shallow root systems can be damaged by over fertilizing.

Watering:

Newly planted boxwoods 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. Boxwoods can also be susceptible to powdery mildew, Pythium root rot, canker and leaf spots. Boxwood blight can be troublesome, causing rapid defoliation and plant dieback. Plants are weakened and made vulnerable to secondary attack from other pests or diseases, leading to plant death. For more, see Boxwood Blight.

Deer resistance:

Boxwoods are a useful part of a deer-resistant garden. 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 ‘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 var. japonica ‘Green Beauty’ and B. sinica var. insularis ‘Winter Gem’)

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

For colder zones: Korean boxwoods survive well in lower temperatures, making them the best choice for cold climate gardens.

One of the most versatile plants in any landscape, the opportunities to use boxwoods 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, Knockout roses, rhododendrons and peonies.