Boxwood is toxic to dogs, cats and horses. When grown as a hedge or formal screen, the primary maintenance for the shrubs will be in regular pruning, though this will not be necessary if you are using them as specimen plantings.
Light
Boxwoods will take full sun to partial shade, but planting them in an area bathed in dappled shade for the hottest part of the afternoon is preferable. When sheltered by trees, the roots of dwarf boxwoods will profit from the cooler soil temperatures.
Soil
Boxwood shrubs require well-drained soils, or they will suffer from root rot. Although they may tolerate soils with a lower pH, they prefer a soil pH in the 6.8 to 7.5 range.
Water
For the first two years, boxwoods require deep weekly watering. Avoid shallow watering, since moisture will not reach the deepest roots. Mature plants will thrive with a deep watering every 2 to 4 weeks.
Temperature and Humidity
Boxwoods typically thrive in the climate conditions in zones 6 to 8. In very hot summer weather, the shrubs will appreciate more water and shade. Zone 5 gardeners may find that stem tips die back in cold weather.
Fertilizer
Fertilize with an all-purpose fertilizer in spring prior to the emergence of new growth. For the amount, follow the product label instructions.
Types of Boxwood Shrubs
There are many kinds of boxwoods, and the best plant for you depends on your particular landscaping needs.
Buxus sempervirons ‘Suffruticosa’ cultivars are favored in gardens because they grow more slowly. The growth habit is tighter and more compact than the ‘Arborescens’ cultivars. These shrubs grow to 2 to 3 feet in height with a 2- to 4-foot spread. B sempervirens’ Arborescens’ is a considerably larger, faster-growing plant, growing as tall as 20 feet with a spread of 8 to 10 feet.B. sempervirens ‘Monrue Green Tower’ is a columnar form, 9 feet tall and 1 to 2 feet in spread. It is great for a tall screen or for topiary use. Two plants can be used to flank an entryway.Buxus microphylla var. japonica, the Japanese boxwood, is one of the most popular shrubs for low hedges. It is also preferred where a more drought-tolerant shrub is needed. It is for zones 6 to 9 and has mature dimensions of 6 to 8 feet tall by 10 to 15 feet wide. Japanese boxwoods figure prominently at a number of historic sites in the Far East.B. microphylla japonica ‘Winter Gem’ is 4 to 6 feet tall with a similar spread. The cultivar’s name comes from the pleasing gold and bronze tinges of its foliage in winter.B. microphylla japonica ‘Golden Triumph’ is 2 to 3 feet tall and 3 to 4 feet wide; it is valued for its variegated leaves.
Pruning
Although they are known for their tolerance for hard pruning, most boxwoods will form a nice informal shape without much pruning at all. Only occasional pruning is required to clean out dead branches or those that are twisted together. When pruning hard for shape, the trimming can be done almost any time during the growing season, though it should be avoided in late fall to avoid winter bronzing.
Propagating Boxwood Shrubs
Boxwood is best propagated by rooting from stem cuttings in midsummer. Here’s how to do it:
How to Grow Boxwood Shrubs From Seed
Growing a boxwood shrub from seed takes time but is often successful. Start with 2-inch pots filled with organic potting soil. Make sure the pots have good drainage holes; the addition of a small amount of gravel in the bottom can help ensure better drainage. Place seeds in wet paper towels and place those paper towels in the refrigerator for one month. Make sure the paper towels stay damp. After the month is up, move the paper towels and seeds to a much warmer place of about 70 degrees Fahrenheit. Keep the paper towels damp and expect germination from your seeds in about one month. Once the seeds sprout, plant them with the sprout side down in the pots, one seed per pot. Cover the pot with plastic wrap and place it in a sunny spot. Keep the soil moist. When a green shoot appears above the soil, remove the plastic wrap. Care for them in their pots until they become too big for the pot, at which point they are ready to be hardened off and transplanted outside.
Potting and Repotting Boxwood
If you choose to grow boxwood in a container, opt for a container that is as wide as the boxwood is high. For example, if you have a 12-inch-tall boxwood, you need a 12-inch diameter pot. When it outgrows its current container, transplant it into one only a few inches bigger, keep the soil moist, and watch the plant for signs that it’s struggling—your soil might need to be amended.
Overwintering
In the northern part of the hardiness range, new growth is susceptible to winter damage. Protect the boxwoods with a burlap wrapping or similar protection during the first several years.
Common Pests and Plant Diseases
Leafminer, boxwood mite, and boxwood psyllid are common pests. The damage is disfiguring but not fatal, and the pests can be treated with horticultural oils. In the deep South, nematodes are of concern. Boxwoods can be susceptible to fungal blights and leaf spot, and root rot can also be a problem in poorly drained soils.
Common Problems for Boxwood Shrubs
A common problem for boxwood is “winter bronzing,” a shift to reddish-brown or yellowish foliage color caused by winter exposure to wind and sun. One way to address the problem is to spray an anti-desiccant on the shrubs in late November and again in late January and to make sure your plants are watered sufficiently throughout the growing season. Also, you can build a structure around your bushes to shelter them from the wind and sun in winter. But some gardeners do not mind—and even actually value—the winter bronzing on the foliage.
