Any artistic masterpiece is improved with the perfect frame. Likewise, a garden—a living masterpiece—is enhanced when surrounded by an elegant border. Defining an herb garden with a solid green edge is like framing a picture: It draws the eye to the beauty within and defines its boundaries.
One of the most easily recognized garden borders, boxwood (Buxus spp.) is also a symbol of the gardener’s long-term commitment and investment. Boxwood’s slow growth habit can be both an advantage and a disadvantage. If you want to plant a classic boxwood border, know that boxwood is not an instant hedge. It may take years to see the lush, thick green hedges of an elaborate Edwardian or Colonial garden.
Start with a plan. The basic idea might come from a book or magazine, or from a park or garden you admire. Those inspirational borders, well-groomed and solid, took years to establish and are probably the beneficiary of year-round attention. But with the proper care and some patience, your garden may someday be a source of inspiration as well.
Boxwood, commonly known as box in England, is one of the oldest ornamental plants. It is thought to have been used in formal hedges by the ancient Egyptians and then later by the ancient Greeks and Romans. The Dutch first brought boxwood to America from Amsterdam in 1653 and grew it near what is now Long Island, New York. There are many established boxwood hedges in America that are 100 or 200 years old.
American boxwood (Buxus sempervirens) and English boxwood (B.s. ‘Suffruticosa’) are the best-known varieties; English boxwood is the true, dwarf form most commonly seen in formal gardens. Originally established in Colonial gardens, traditional European varieties continue to dominate the American landscape. As boxwood’s popularity grows, many more Asian and American varieties are appearing in modern landscapes.
Boxwood’s uses extend beyond the garden border. The woody portions of the plant have been used to treat rheumatism, syphilis and other venereal diseases. It was thought to cure leprosy and has been used in cases of epilepsy, piles and for toothaches. The leaves in powdered form are an effective vermifuge. Boxwood has cosmetic uses as well. Various perfumes were made from the leaves and bark, and a decoction was recommended to promote hair growth. An auburn hair dye was created by boiling the leaves and sawdust in lye. On the farm the dried and powdered leaves were used to improve the coats of horses, and some English farmers still use the old-fashioned remedy of using powdered leaves to treat intestinal worms in horses. The wood of the boxwood plant is tough and heavy, rivaling brass in its strength, which makes it ideal for use in engraving. Boxwood has also been used to make musical instruments, rulers and other items that call for rigid, non-expansive material.
About 115 boxwood cultivars are commercially available in a wide variety of sizes up to about 30 feet. Hedges and herb garden borders are usually dwarf varieties, which reach about 3 feet. All boxwood is evergreen with opposite dark green leaves. Long known to craftsmen for its strong wood, boxwood also has a reputation for low maintenance. Much of the attention boxwood requires can be given in the less-hectic fall and winter months, but a year-round border patrol is recommended. Boxwood is sometimes the only greenery remaining in a winter herb garden. A dense, green year-round standout, it is well worth the long start-up time.
The best time to plant and mulch boxwood is in the fall. In the winter, prune, thin and protect shrubs. Winter protection may be necessary, especially from drying winds and sun exposure. Foliage tends to turn bronze in the winter due to cold and exposure. Remove damaged or dead branches so new growth will fill the vacant areas. The largest selection of boxwood nursery stock is available in spring, which is another good time to plant new shrubs and inspect for insects. In the summer, keep boxwood weed-free and water well.
Jack Roberson breeds award-winning plants, perennials and shrubs. Although he is most recognized as the creator of American daylily ‘Stella De Oro’, Roberson’s recent horticulture venture is breeding boxwood.
“Good choices for boxwood borders are ‘Green Mountain’, ‘Green Velvet’ and ‘Winter Green’,” Roberson says. “All are very cold-hardy and good choices for hedges in (USDA Hardiness) Zone 6. Another good choice for small gardens is ‘Morris Midget’(B.m. var. japonica ‘Morris Midget’) because it is a compact, low-growing mound. Like most boxwood, it will tolerate full sun or part shade.”
Boxwood is susceptible to too much water in the summer and winter. Planting in low-lying areas, or under a downspout, even in the hottest part of the country, is a bad idea. Roberson uses cottonseed meal (a natural slow-release fertilizer) to fertilize his boxwood gardens. Boxwood is hardy through Zone 5 with some protection.
Boxwood plants are somewhat expensive. Buying enough established boxwood to outline even a small herb garden can strain any budget. A good way to test your selection before investing in dozens of the same variety is to buy one or two boxwoods and plant them in the garden as a focal point, or purchase four plants to establish the corner posts of your garden. Boxwood planted in containers also can serve to define a garden’s borders. From these few anchors in the garden, make cuttings to multiply the boxwood and establish a garden frame (see “Making More,” Page 18). Cuttings and layering are the best ways to increase your stock.
Plant a few extras when the herb garden border is established. Use these back-up boxwood plants, grown in containers or in another isolated part of the yard, to replace injured or weak plants. Test planting and asking your local agricultural extension office and local herb growers are the best ways to select hardy boxwood that is suited to your microclimate and landscape plan.
Spacing plants and giving them plenty of room to establish roots will prevent overcrowding and reduce disease and maintenance. Well-spaced starter boxwood shrubs may, at first, look lost. If definition is important to you, then consider annuals to fill gaps until the boxwood begins to define your garden.
Colorful and fast-growing coleus (Coleus blumei) or the deep greens of basil (Ocimum basilicum) will quickly fill spaces between boxwood shrubs until the boxwood grows to fill the frame or border. Both plants can be pinched back or trimmed to form a temporary hedge.
Traditional boxwood borders or knot gardens are not accomplished in a single garden season. The keys to a successful boxwood border or knot garden are time and patience. The efforts are rewarding.
Newly planted boxwood needs the care and attention that any newly planted woody shrub or tree requires. Boxwood tends to be deer-resistant and have few insect problems. Insect pests such as psyllids, leaf miners and mites are usually minor problems on well-spaced and pruned plants.
• Boxwood roots like well-drained soils. Root rot is a problem in poorly drained soils.
• Use organic mulch, such as shredded hardwood bark, pine needles and shredded leaf mulch, to control weeds. A 1-inch layer of organic mulch will prevent soil erosion and moisture loss and protect roots. Fertilize with an annual application of rich compost.
• Avoid digging around boxwood’s shallow fibrous root system. Boxwood is easily damaged or killed with too much cultivation in the bordered herb garden or flowerbed. It does not tolerate foot traffic or compacted soil.
• Prune dead or damaged branches to revive growth. While shearing may be necessary on huge estate gardens, most home gardeners will benefit by taking the time to hand prune boxwood, observing signs of stress or insect infestation. Thinning and hand trimming hedges will allow for a denser, hardier border.
The quickest way to produce a lot of boxwood plants is by taking stem cuttings from a parent plant. The advantage will be progeny identical to the parent plants.
Remove cuttings from 1- or 2-year-old branches anytime from July to December and place into containers filled with simple potting mixes. Take cuttings that are 3 to 4 inches long. Remove lower leaves and place cuttings an inch deep in a shallow container filled with equal amounts of sharp builder’s sand and perlite, or a mix of half pine bark and half perlite. High humidity and good drainage are ideal rooting conditions. Cover with plastic. Water cuttings by misting with a spray bottle. Gradually remove the plastic covering to harden off the plant.
Roots should appear in two to three months. After roots have formed, transplant cuttings into their own individual containers. Little boxwood plants do well in a greenhouse or outdoors in a protected area for two or three years until they are ready to be planted in the garden.
When growing boxwood in containers, use a slow-release fertilizer in the soil mix. Because regular watering and good drainage is necessary in containers, nutrients tend to leach out of soil mix. Do not overfertilize boxwood as the shallow roots are easily burned by direct contact with strong commercial fertilizers. Always use a low concentration of fertilizer, never more than 10-10-10.
Freelance writer and Master Gardener Patsy Bell Hobson recently moved to a 150-year-old home in Cape Girardeau, Missouri. To her delight, the property included an established boxwood hedge that provides a resource for cuttings and mandatory lessons in care, maintenance and pruning.
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