Shrub · Buxaceae
Common Boxwood
Buxus sempervirens
Densely leaved and evergreen year-round, boxwood holds a deep, even green that forms the backbone of a clipped garden.
Full sun
Every 5–10 days
USDA 5–8
5–15 ft · 1.5–4.6 m
Overview
Boxwood reads as a solid mass of small, deep green leaves packed tight along fine, closely set twigs. It is a slow-growing evergreen shrub in the box family, and that dense branching is what lets it be sheared into the crisp surface of a hedge, a low edging, or a smooth rounded ball. Left unshaped it can climb to 15 feet, the foliage carrying its even green all the way up.
Up close, the plant is all texture and restraint. Each season adds only a little new growth, the fresh leaves emerging a brighter green against the older, deep evergreen foliage behind them, so a mature plant is a slow accumulation of countless small leaves. That same foliage holds its color through deep shade to full sun, stays green through cold to zone 5, and persists for decades once the plant is rooted.
The plant's troubles are written on its leaves and stems if you look. Boxwood blight can spot and drop the foliage within days, leafminers and mites pock and dull the leaf surface, and root rot works unseen below. A well-chosen spot, clean foliage, and air moving through the canopy keep that close green surface intact.
Care
The short version: boxwood holds its dense green foliage from full sun to full shade, roots into evenly moist but well-drained loam, and adds so little growth each year that one shaping after the last spring frost keeps its leafy surface even.
Light
Boxwood holds its dense green foliage across full sun to full shade, with the leaves packing in thickest under sun. The one light to keep off it is full winter sun on an exposed site, which burns the evergreen leaves to a scorched brown.
Water
The soil stays best evenly moist but never soggy, watered roughly every 5 to 10 days once established. The roots run shallow just beneath the surface, so 1 to 2 inches of organic mulch keeps them cool and damp, and the soil over them is left undisturbed. Overwatering and poor drainage rot those shallow roots.
Soil
Boxwood roots into well-drained loam held evenly moist. The leaves stay healthy across a pH from 6.0 to 8.0, so slightly acidic through slightly alkaline ground all suits it. Heavy, waterlogged clay is the soil that smothers the roots and is best amended or avoided.
Temperature
The evergreen foliage endures a wide range, from about -20°F to 100°F (-29°C to 38°C). The leaves suffer less from the thermometer than from exposure, since drying winter wind and sun pull moisture from them faster than cold alone harms them.
Humidity
Ordinary outdoor humidity keeps the foliage in good order, so no level needs managing. Air moving through the dense canopy matters more, because still, damp air trapped among the close leaves is what blight and other fungal diseases settle into.
Feeding
A balanced fertilizer in spring keeps the leaves a deep, even green through the year. Paired with good mulch over the roots, that yearly feeding holds the foliage dense and well-colored without anything more.
Pruning
Boxwood is sheared after the last spring frost and never before, since an early cut pushes soft new leaves into a late freeze. Dead or browned branches come out as they show, and any leaves caught in the branch crotches are raked clear, since that trapped litter is where leaf disease begins.
Repotting
Boxwood is rarely repotted and sulks when its roots are disturbed. In a container, roots circling the pot, water draining straight through, or new leaves that stall in size all signal it is time to move up a pot.
Size & spacing
Plants reach 5 to 15 feet (1.5 to 4.5 m) tall and about as wide, the small leaves carried evenly across the whole form, though shearing keeps most far smaller. Spaced to its mature spread, a hedge lets air slip between the dense canopies and leaves disease less foothold among the leaves.
When to plant
Boxwood is set into the ground in spring or early fall, while the soil is workable and the weather is mild. A spot sheltered from harsh wind and full winter sun protects the evergreen leaves, and the roots take a season to knit in before summer heat or deep cold reaches the foliage.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or early fall, in a site sheltered from strong winds and full winter sun
- Harvest: April to May (greenish-cream, insignificant flowers)
Hardiness
USDA hardiness zones: 5–8
Temperature: down to -29°C
Troubleshooting
Boxwood keeps its even green surface for years, then shows its few faults across the leaves all at once. Most signs are plain on the foliage, from browning and bare twigs to raised blisters and a fine silvery stippling, while the worst start unseen at the roots and only later pale the leaves. Match the look of your plant below and act early, since the serious diseases leave no cure.
Brown leaf spots, fast leaf drop, and dark stem cankers
Circular brown spots that spread across the leaves, leaves dropping within days, and dark brown to black lesions on the stems mark boxwood blight, a fast-moving fungus, though Volutella blight can scar the stems and leaves the same way after winter injury. Once it is in the plant there is no cure. The diseased stems are cut out and bagged, every fallen leaf is raked up, fresh mulch goes down, and a chlorothalonil fungicide coats what foliage remains.
Fix:
- Remove and bag diseased stems and rake up all fallen foliage
- Apply fresh mulch over the soil surface
- Apply chlorothalonil, or chlorothalonil mixed with thiophanate methyl, fungicide
Yellowing foliage over rotted roots and peeling crown bark
Foliage shifting from dark green to light green to yellow over roots that come up dark and rotted is Phytophthora root rot, settled in wet, poorly drained soil. At the crown the bark peels loose once it is infected. No spray reaches it, so the answer is better drainage, amended heavy clay, or a raised bed, with less water at the roots.
Fix:
- Improve soil drainage
- Amend heavy clay soils or plant in raised beds
- Avoid overwatering
Swollen, blistered leaves with yellow blotches
Raised blisters that swell the leaf and stain it yellow or brown are the boxwood leafminer at work, its larvae feeding within the leaf tissue. Split a blistered leaf and small orange maggots sit inside the mine. The adult flies appear from mid-April into early May, and treatment is a foliar spray of acephate or spinosad, or a soil drench of imidacloprid.
Fix:
- Apply acephate or spinosad foliar spray to larvae in mines
- Use malathion contact spray against adults
- Apply soil-applied dinotefuran or imidacloprid
Dull, silvery, finely stippled leaves
A fine scatter of tiny yellow scratch-like flecks across the upper leaf, dulling the surface to a dingy silver, is the mark of the boxwood mite. Tap a branch over white paper and the tiny mites drift across it. Horticultural oil at 1 to 2 percent or insecticidal soap clears them, and plants stressed in hot, baking sun show it worst, since heat speeds the mites along.
Fix:
- Apply horticultural oil at 1-2 percent to kill eggs and adults
- Apply insecticidal soap
- Apply tau-fluvalinate miticide if needed
Cupped new leaves under white waxy fluff
New leaves that curl and cup inward, capped with a white waxy fluff, show the boxwood psyllid drawing sap from the soft growth. Pry the distorted shoots apart and small pale-green nymphs sit beneath that white waxy coating. The damage is mostly cosmetic on the leaf, so light cases are left alone, and acephate is used only when an infestation runs heavy.
Fix:
- Treat only heavy infestations
- Apply acephate foliar spray
- Apply soil-applied dinotefuran or imidacloprid
Brownish-yellow foliage in late winter
Evergreen leaves turning a dull brownish-yellow in late winter are showing winter bronzing, brought on by open winter sun and drying wind. The color looks alarming but rarely harms the plant, and the new spring leaves come in a fresh, healthy green. Plants sheltered from wind and harsh winter sun, watered well in fall, and mulched over the shallow roots keep their green.
Fix:
- Site or transplant plants where they are sheltered from winter wind and full winter sun
- Ensure adequate fall soil moisture before winter
- Apply organic mulch to protect shallow roots
Toxicity
Boxwood is toxic, and none of its small green leaves or fine stems is safe to eat. The foliage and stems carry steroidal alkaloids, chiefly buxine, that cause vomiting and diarrhea in pets and people, and large amounts can lead to seizures or respiratory failure in horses and livestock. A sharp, bitter taste in the leaves turns most animals away before they swallow much, but pets, grazing stock, and children should be kept clear of the foliage and any prunings.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Moderate
A cat that chews the small leaves usually drools, then vomits, with diarrhea soon after. The bitter taste of the foliage stops most cats before they eat enough to cause real harm.
Dogs Moderate
A dog that nibbles the foliage or gnaws fallen prunings shows vomiting and diarrhea soon after. Clippings are best raked up and kept out of reach during a trim.
Horses Severe
Horses are hit hardest. The alkaloids in the leaves can bring on colic, diarrhea, seizures, and in large amounts respiratory failure, so boxwood and its trimmings stay well away from any paddock.
Rabbits Toxic
The same buxine in the leaves and stems that sickens other animals makes boxwood unsafe for rabbits. The foliage is never offered, and the shrubs stay fenced off from any free-ranging rabbit.
Livestock Severe
Cattle, goats, and sheep can suffer serious digestive and respiratory trouble from the foliage, and heavy grazing has proven fatal. The bitter leaves deter most stock, though hungry animals still try them.
Birds Toxic
No part of boxwood is safe for birds to eat. Poultry and pet birds are kept from pecking at the leaves or scattered clippings.
People Caution
No part of boxwood is edible, and eating the small leaves or stems causes vomiting and diarrhea. The sap also irritates sensitive skin, so gloves are worn during pruning and curious children kept away from the foliage.
Sap can cause contact dermatitis in sensitive people; wear gloves when pruning.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Boxwood varies in form and in the color of its leaves, from low blue-toned mounds to slim upright columns, and a few cultivars are worth knowing for the look of their foliage or their resistance to pests.
Vardar Valley
A low, spreading form near 2 to 3 feet tall whose leaves carry a distinct bluish cast, and it shrugs off the boxwood leafminer that troubles other types.
Suffruticosa
The classic English boxwood, a dense, fragrant dwarf of tightly packed small leaves that grows painfully slowly and resists leafminers the least of any cultivar.
Dee Runk
A narrow column of dense foliage rising to about 8 feet tall while holding to just 2.5 feet wide, a slim vertical accent.
Elegantissima
A variegated cultivar whose every leaf is ringed with a creamy-white margin against the green center.
How to propagate
Boxwood is slow but reliable to root from cuttings, and a short, leafy piece of stem is all it takes to grow a true copy of a plant whose foliage you admire.
Stem cuttingsModerate
Mid-July to early fall (semi-hardwood, current season's growth) · Several weeks to a few months to root
Boxwood roots readily from cuttings given time. Semi-hardwood pieces of the current season's growth, their stems just firming and still leafy, are taken from mid-July into early fall from healthy, disease-free plants, and kept moist and shaded while worked. Rooting is slow, running from several weeks to a few months, and firmer hardwood cuttings strike just as well.
Myths
Boxwood is harmless to pets because it is just a common landscape hedge.
Every part of the plant holds alkaloids that are toxic to dogs, cats, and horses. A pet that chews the small leaves gets vomiting and diarrhea, and horses can react far worse. Being a familiar hedge doesn't make it safe to eat.
A spray will cure boxwood blight once a plant is infected.
Nothing cures the disease once it is in the plant. Boxwood blight can only be managed, never reversed, by cutting out infected stems, keeping the fallen leaves cleared, and coating healthy foliage with protective fungicides to slow the spread.