Shrub · Berberidaceae
Japanese Barberry
Berberis thunbergii
Tough, thorny, and richly colored, and forgiving to grow, yet worth a careful thought before you plant it where it can spread.
Full sun
Every 7–14 days
USDA 4–8
3–6 ft · 0.9–1.8 m
Overview
Japanese barberry is a dense, rounded deciduous shrub, and it is one of the more forgiving ones you can grow. It reaches 3 to 6 feet (91 to 183 cm) tall and spreads even wider, carrying small leaves that turn red, purple, or gold depending on the cultivar you choose. Pale yellow flowers open in late spring, then bright red berries follow in fall and hang on happily well into winter.
If you are new to shrubs, this is a reassuring one to start with, because almost nothing seems to bother it. It copes with drought once it has settled, puts up with poor soil and city air, and deer leave it be thanks to the sharp single spines at every node. That same thorny armor makes it a fine low hedge and a quiet deterrent under a window.
There is one catch, and it is an honest one to know up front. Across much of the eastern and midwestern US this plant has slipped past the garden fence and turned badly invasive, and its thickets are linked to higher deer-tick numbers. In several states it is a regulated noxious weed, so the kindest first step, both for you and your neighborhood, is simply checking whether you can legally plant it at all.
Care
The short version: give it full sun for the richest color, tuck it into any well-drained soil, water it while it settles and then largely let it be, and always slip on thick gloves before you prune.
Light
Give it full sun for the strongest leaf color, especially the lovely purple and gold forms. It will happily take partial sun and even partial shade, though the foliage drifts toward green and the shrub grows a touch looser in the shade.
Water
Water regularly through the first season while the roots take hold, and after that you can ease right off, since it is drought tolerant once established. Let the top half of the soil dry between waterings, roughly every 7 to 14 days, and just be sure it never sits in soggy ground.
Soil
This is about as easygoing as shrubs get, settling into dry to medium soil of almost any texture, from clay to loam to sand. The single thing it will not forgive is poor drainage, so a spot that drains well matters far more than rich ground.
Temperature
You have plenty of room here, as it is a cold-hardy plant that is comfortable from about -29°F to 100°F (-34°C to 38°C), covering a wide stretch of the country. Hard winters and hot summers pass without complaint.
Humidity
Ordinary outdoor humidity suits it perfectly, so there is nothing to fuss over there. What matters more is air movement, because a damp, crowded canopy is where the few leaf diseases like to start.
Feeding
It rarely asks to be fed and generally thrives in average soil with nothing added, so you can happily skip this most years. If the growth ever looks weak, a light application of balanced granular fertilizer in spring is all it needs.
Pruning
Keep pruning light unless you are shaping a formal hedge, and there is no need to be timid. Cut right after flowering or in late winter, and an overgrown plant can be taken down hard in late winter and it will recover. Always wear thick gloves, because the stems are packed with spines.
Repotting
A container plant rarely needs moving on. Pot it up only when you notice roots circling the pot or peeking out the drainage holes, water running straight through, or new growth that has quietly stalled.
Size & spacing
A mature plant stands 3 to 6 feet (91 to 183 cm) tall and spreads wider still, around 4 to 7 feet (122 to 213 cm) across. Give each shrub that much elbow room so the canopy stays open and air can move freely through it.
When to plant
Think of this as a fall-and-spring shrub rather than a seasonal crop, which takes a lot of the pressure off. Set new plants out in spring or fall wherever it is legal, look forward to pale yellow flowers in late spring, and enjoy the red berries coloring up in fall and clinging on through winter.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall where legal to plant
- Harvest: Pale yellow flowers in late spring (April to May), followed by bright red berries in fall persisting into winter
Hardiness
USDA hardiness zones: 4–8
Temperature: down to -34°C
Troubleshooting
Japanese barberry is rarely much trouble, and when something does go wrong it usually traces back to wet soil or a crowded, airless canopy. Match what you are seeing below and act early, and a small hiccup stays a small hiccup.
Whole branches wilting and dying back as the shrub fades
This one is worth catching early, and soggy soil is nearly always behind it. Root rot takes hold when the ground stays wet, and once the roots have gone dark and soft those stems sadly won't recover, however carefully you water. Improve the drainage, lift out any plant that is too far gone, and you can spare yourself the heartache next time by keeping this shrub out of low, wet ground.
Fix:
- Improve soil drainage
- Remove severely affected plants
- Avoid planting in wet sites
Dark spots on the leaves and leaves dropping too soon
Don't panic if you spot this, because it is almost always anthracnose or a bacterial leaf spot getting a foothold in wet weather inside a crowded shrub. Pick off the marked leaves, tidy up any that have fallen, and open the plant up so a breeze can pass through. Water at the roots rather than over the leaves and it will bounce back.
Fix:
- Remove and dispose of infected leaves and debris
- Thin the shrub to improve air circulation
- Avoid overhead watering
Curled new shoots, a sticky film, or little bumps on the stems
Two small pests are usually at work here, and both are easy to handle. Aphids gather on the soft spring shoots and leave that sticky honeydew behind, while scale insects cling on as hard waxy bumps down the stems. A firm spray of water or a little insecticidal soap sees off the aphids, and you can prune away or dab oil on the worst of the scale.
Fix:
- Spray aphids off with water or apply insecticidal soap
- Prune out heavily scale-infested branches
- Apply horticultural oil for scale
Toxicity
This shrub is only mildly toxic, though it is not entirely harmless, so a little care goes a long way. The leaves, bark, and roots hold berberine, a bitter compound that can upset the stomach if a pet, child, or animal eats much of it. The everyday concern is really mechanical, since the sharp spines at every node scratch and puncture skin, so wear gloves and keep small children clear of the canopy and all will be well.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · People
Safe for
Birds
Cats Caution
A curious cat can take a nibble without much harm, though the berberine in the leaves and roots may unsettle its stomach if it eats a good deal, leaving you with drooling, vomiting, or loose stools. The thorns are the thing to watch most, since they can scratch a mouth or paw.
Dogs Caution
A small taste rarely bothers a dog, but chewing through the leaves or roots in any quantity can bring on drooling, vomiting, or loose stools from the berberine. Keep an eye on those sharp spines around an eager, sniffing nose.
Horses Caution
You can relax a little here, as horses usually steer clear of the thorny stems, and the berberine is only a gentle gut irritant anyway. It is the spines you want to mind if a horse leans into the canopy.
Rabbits Caution
The thick spines tend to keep rabbits away, which is a small blessing, because the bitter berberine can leave a little animal with an upset tummy. It is best not offered as forage.
Livestock Caution
Cattle, goats, and sheep mostly give the thorny growth a wide berth, and even a browse does no more than mildly irritate the gut. The thickets are better known for harboring ticks than for troubling your stock.
People Caution
People have leaned on the berries and bark in herbal medicine for a long time, yet eating much of any part can leave you with stomach cramps, nausea, and diarrhea from the berberine. Far more often it is the sharp single spines at every node that catch someone, so slip on gloves and keep little ones clear.
Birds None
Birds happily eat the bright red berries with no ill effect at all, then carry the seed far and wide, which is a big reason this shrub spreads the way it does.
Stems are densely covered with sharp single spines at each node that readily scratch or puncture skin; wear thick gloves and long sleeves when handling or pruning, and keep children and pets clear of the thorny canopy.
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
Most of the named forms are grown for leaf color rather than flower or fruit, so pick the shade you love. These are the ones you are most likely to come across.
'Atropurpurea'
If you want the classic purple-leaved barberry, this is it, holding a warm reddish-purple to deep burgundy all season long.
'Crimson Pygmy' (var. atropurpurea)
A neat little mound of deep crimson-purple leaves that many gardeners choose for low edging and tidy borders.
'Aurea'
A golden-yellow form that glows brightest for you when it is given full sun.
How to propagate
Japanese barberry multiplies all too easily, which is a mixed blessing: it means rooting a new plant is simple, and it is also why the shrub has become such a problem in the wild.
Stem cuttingsEasy
Softwood cuttings in early summer or hardwood cuttings in late fall/winter · 4 to 8 weeks to root
You will find cuttings root with hardly any effort. Take softwood cuttings in early summer or hardwood ones in late fall and winter, and they settle in and strike roots in 4 to 8 weeks. Low branches even root by themselves wherever they lean against the soil, a habit called layering that helps the shrub spread on its own.
SeedEasy
Seed ripens in fall and is widely bird-dispersed · Germinates the following spring, often at very high rates
Seed ripens in fall, birds carry it off, and it comes up the next spring at very high rates. That eager self-seeding is the very reason the plant runs wild, so please do not raise it from seed where it is prohibited.
Myths
Japanese barberry is a harmless, well-behaved shrub you can plant anywhere.
In truth it ranks among the worst invasive shrubs across the eastern and midwestern US, slipping out of gardens on bird-dropped seeds and on branches that root wherever they touch the ground. A number of states now ban or restrict its sale as a noxious weed, and its dense thickets go hand in hand with higher black-legged tick numbers. Do take a moment to check your state and local rules before planting, and lean toward the sterile cultivars or a friendly native instead.