Shrub · Buxaceae
Common Boxwood
Buxus sempervirens
A slow, evergreen year-round broadleaf shrub that forms the structural backbone of a clipped, formal garden.
Full sun
Every 5–10 days
USDA 5–8
5–15 ft · 1.5–4.6 m
Overview
Boxwood earns its place wherever a garden needs persistent green architecture that holds form through the seasons. As a slow-growing evergreen shrub in the Buxaceae, its dense, fine branching is what allows close shearing into a tight hedge, a low edging, or a rounded specimen. Unpruned it can reach 15 feet, but the slow habit means most plantings are held well below that with routine shaping.
The slow growth rate is the governing trait behind almost every decision you make with boxwood. Because annual extension is minimal, a mature hedge represents years of accumulated growth, which is why it is planted as a long-term investment rather than a fast screen. That same restraint comes with real range: the species takes deep shade to full sun, withstands cold to zone 5, and persists for decades once established.
Its weaknesses are few but consequential, and most trace back to moisture and air. Boxwood blight can defoliate a plant within days, leafminers and mites disfigure foliage, and saturated soil drives root rot. Correct siting, sanitation, and spacing for airflow address the common thread, since still, humid conditions favor the fungal pathogens that cause the worst of the damage.
Care
The short version: boxwood spans full sun to full shade, requires evenly moist but well-drained loam to keep its shallow roots aerated, and grows slowly enough that a single shaping after the last spring frost meets most of its pruning needs.
Light
Boxwood is notably plastic in its light requirement, performing across full sun to full shade. Growth is densest in sun, where higher light supports more branching, but full winter sun on an exposed site is the exception to avoid, because it scorches the evergreen foliage brown.
Water
Maintain the soil evenly moist but never saturated, irrigating roughly every 5 to 10 days once established. The root system is shallow, so 1 to 2 inches of organic mulch moderates soil moisture and temperature, and cultivation near the base should be avoided to prevent root injury. Overwatering and poor drainage are the direct precursors to root rot.
Soil
Site boxwood in well-drained loam held evenly moist. It tolerates a broad pH from 6.0 to 8.0, so slightly acidic through slightly alkaline soils all suit it, which reflects its adaptability rather than indifference. Heavy, waterlogged clay is the condition to amend or avoid, since impeded drainage is what predisposes the plant to root pathogens.
Temperature
The species is hardy across a wide range, from about -20°F to 100°F (-29°C to 38°C). The limiting factor is rarely temperature itself but exposure, because desiccating winter wind and sun draw moisture from the evergreen leaves faster than frozen roots can replace it, which causes more injury than cold alone.
Humidity
Ambient outdoor humidity is sufficient, so no target level applies. Air movement matters far more than humidity, because stagnant, damp conditions within a crowded planting create the leaf-wetness and still air that fungal pathogens such as blight require to establish.
Feeding
A balanced fertilizer in spring supplies what boxwood needs to sustain vigor through the season, timed to coincide with the flush of new growth. Combined with adequate mulch, that single annual feeding maintains foliage color and density without additional inputs.
Pruning
Shape boxwood after the last spring frost and never before, because pruning stimulates tender new growth that a late freeze would kill. Remove dead or diseased branches promptly to limit pathogen spread, and rake leaves lodged in the branch crotches, since trapped debris holds moisture and serves as an infection court.
Repotting
Boxwood is rarely repotted and responds poorly to root disturbance once established. In containers, monitor for roots circling the pot, water draining straight through, or stalled growth, all signs of a root-bound plant, and step up the pot size only when they appear.
Size & spacing
Mature plants reach 5 to 15 feet (1.5 to 4.5 m) in height and a comparable spread, though shearing holds most far smaller. Spacing a hedge to its mature spread is a disease measure as much as a sizing one, because adequate gaps let air move between plants and reduce the leaf wetness that fungal disease exploits.
When to plant
Boxwood is best planted in spring or early fall, when soil is workable and temperatures are moderate enough to limit transplant stress. Choose a site sheltered from strong wind and full winter sun, and allow the root system one mild season to establish before it faces the moisture and temperature extremes of summer or hard winter.
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 can remain sound for years, then express several problems in sequence as conditions shift. Most disorders register in the foliage, from abrupt browning and defoliation to blistering and stippling, while the most serious begin unseen in the root zone. Diagnose against the descriptions below and intervene early, since the severe diseases cannot be cured once established.
Brown leaf spots, sudden defoliation, and dark stem cankers
These symptoms most often indicate boxwood blight, a fast-moving fungus that defoliates a plant within days, though Volutella blight can produce similar damage after winter injury weakens the tissue. No treatment cures the infection once it establishes. Excise and bag the diseased stems, rake up all fallen foliage, apply fresh mulch to bury inoculum, and protect remaining growth with a chlorothalonil fungicide.
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
A plant fading from green to yellow over dark, decayed roots points to Phytophthora root rot, a water mold that thrives in wet, poorly drained soil. The crown confirms it, since the bark peels away once infection reaches that point. No fungicide reverses the disease, so the remedy is cultural: improve drainage, amend heavy clay, or relocate the plant to a raised bed, and reduce irrigation to deny the pathogen the saturated conditions it needs.
Fix:
- Improve soil drainage
- Amend heavy clay soils or plant in raised beds
- Avoid overwatering
Blistered, swollen leaves with yellow blotching
The raised blisters are feeding galleries of the boxwood leafminer, whose larvae develop inside the leaf tissue. Splitting a blistered leaf exposes the orange maggots within the mine, which confirms the diagnosis. Monitor for adult fly emergence from mid-April into early May, the window when treatment lands best, then apply 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
Dingy, silvery foliage with fine stippling
Fine yellow scratch-like flecks and a dull silvery cast are diagnostic of the boxwood mite, whose feeding removes chlorophyll from the upper leaf surface. Tapping a branch over white paper dislodges the tiny mites, making them visible as they move. Suppress them with horticultural oil at 1 to 2 percent or insecticidal soap, and keep plants out of hot, baking sun, where heat stress accelerates mite reproduction.
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 with a white waxy coating
The boxwood psyllid extracts sap from expanding shoots, and that feeding deforms the new leaves into a cupped, curled shape. Opening the distorted shoots reveals small pale-green nymphs sheltered under a white waxy secretion. The injury is largely cosmetic, so light infestations warrant no action, and acephate is justified only when populations become heavy.
Fix:
- Treat only heavy infestations
- Apply acephate foliar spray
- Apply soil-applied dinotefuran or imidacloprid
Brownish-yellow foliage in late winter
A dull brownish-yellow cast on plants exposed to open winter sun and drying wind is winter bronzing, caused by water loss the frozen roots cannot replace. The discoloration is unsightly but rarely harmful, and new spring growth typically emerges a normal green. Site or move plants where they are sheltered from wind and harsh winter sun, ensure good fall soil moisture, and mulch to insulate the shallow roots.
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 no part of it is safe to ingest. Foliage and stems contain steroidal alkaloids, principally buxine, which induce vomiting and diarrhea in pets and people, while larger doses can produce seizures or respiratory failure in horses and livestock. The compounds are intensely bitter, which limits intake in most animals, but pets, grazing stock, and children should be kept away from the foliage and any prunings.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Moderate
A cat that chews the foliage typically begins drooling, then vomits, with diarrhea following shortly after. The intense bitterness usually limits intake before a cat consumes enough to cause serious harm.
Dogs Moderate
Vomiting and diarrhea develop soon after a dog ingests foliage or chews fallen prunings. Raking clippings up and keeping them out of reach during a trim removes the most accessible source.
Horses Severe
Horses are affected most severely. The alkaloids can induce colic, diarrhea, seizures, and at high doses respiratory failure, which is reason to keep boxwood and its trimmings well clear of any paddock.
Rabbits Toxic
The buxine that sickens other animals renders boxwood unsafe for rabbits as well. The leaves and stems should never be offered, and the shrubs should be fenced off from any free-ranging rabbit.
Livestock Severe
Cattle, goats, and sheep can develop serious digestive and respiratory disturbance from the foliage, and heavy grazing has proven fatal. The bitterness deters most stock, though hungry animals will still sample it.
Birds Toxic
No part of boxwood is safe for birds to consume, so poultry and pet birds should be kept from pecking at the leaves or scattered clippings.
People Caution
No part of boxwood is edible, and consuming the leaves or stems can cause vomiting and diarrhea. The sap also irritates sensitive skin, so gloves are advisable during pruning and children should be kept away.
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
Cultivar selection in boxwood ranges from low spreading mounds to narrow upright forms, and a few are worth knowing by name for their habit or their resistance to specific pests.
Vardar Valley
A low, spreading selection that matures around 2 to 3 feet with distinctly bluish foliage and notable resistance to the boxwood leafminer that afflicts other types.
Suffruticosa
The classic English boxwood, a dense and fragrant dwarf whose extremely slow growth is matched by the poorest leafminer resistance of any cultivar.
Dee Runk
A narrow, columnar form that reaches roughly 8 feet in height while holding to about 2.5 feet in width, suiting it to a confined vertical accent.
Elegantissima
A variegated cultivar valued for the creamy-white margins that edge every leaf.
How to propagate
Boxwood is slow but dependable to propagate vegetatively, and cuttings are the standard route because they preserve the exact characteristics of the parent plant.
Stem cuttingsModerate
Mid-July to early fall (semi-hardwood, current season's growth) · Several weeks to a few months to root
Boxwood roots reliably from cuttings provided the timeline is respected. Collect semi-hardwood pieces of the current season's growth from mid-July into early fall, take them only from healthy, disease-free plants, and hold the cuttings moist and shaded during preparation. Rooting proceeds slowly over several weeks to a few months, and hardwood cuttings root with comparable success.
Myths
Boxwood is harmless to pets because it is a common landscape hedge.
All parts of the plant contain alkaloids toxic to dogs, cats, and horses. A pet that chews the foliage develops vomiting and diarrhea, and horses can react far more severely. Familiarity as a hedge does not make the plant safe to eat.
A fungicide will cure boxwood blight once a plant is infected.
No product cures the disease once the pathogen is inside the plant. Boxwood blight can only be managed, never reversed, through removing infected material, maintaining strict sanitation, and applying protective fungicides to slow spread to healthy plants.