Shrub · Berberidaceae
Oregon Grape
Mahonia aquifolium
Give it shade and shelter from winter wind, and Oregon grape hangs out yellow spring flowers and dusty blue-black berries.
Partial shade
Every 7–14 days
USDA 5–8
3–6 ft · 0.9–1.8 m
Overview
Oregon grape is an evergreen shrub from the Pacific Northwest, and its holly-like leaves are the thing you notice first: each one a compound blade of stiff, glossy leaflets edged with sharp, spine-tipped teeth. In cold weather that dark green surface flushes bronze and purple, then settles back to a deep, lacquered green as spring warms. It sits in the barberry family, not the grape family, and borrows its name from the fruit.
The shrub is slow, thickening to 3 to 6 feet tall over years, its woody stems stacking the leathery leaflets in tiers. Below ground it creeps outward on stolons, pushing up fresh suckers that fill in around the parent into a low, dense colony. Left alone, those shoots weave a knee-high thicket of prickly, evergreen foliage across a shaded bank.
In early spring the tips carry dense, upright racemes of small bright yellow flowers, and by late summer these give way to clusters of round, dusty blue-black berries with a pale bloom, the kind birds strip and people cook into jelly. Hardy to -20°F (-29°C), the tough foliage rides out hard winters wherever drying wind cannot reach it.
Care
The short version: set it in partial shade with shelter from winter wind, in moist, acidic, well-drained soil, and keep it watered until the roots take. After that the glossy shrub asks for little beyond a spring tidy-up.
Light
Oregon grape holds its deepest, most lacquered green in partial to full shade. In full sun the glossy leaflets bleach toward a washed yellow-green and scorch at the spined edges, worst through winter, so overhead shade keeps the surface dark and clean.
Water
Keep the soil evenly moist through the first season or two while the roots reach out. Once established the shrub takes dry spells in stride, so let the top inch dry and water only every 7 to 14 days. What it will not stand is roots sitting in waterlogged ground.
Soil
Give it moist, rich, acidic, well-drained ground in the 5.0 to 7.0 pH band. Alkaline, compacted, or soggy soil turns the leaflets a sickly yellow, and lime is the fastest way to drain the green out of them.
Temperature
The leathery foliage is cold-hardy from about -20°F to 90°F (-29°C to 32°C). Deep cold alone leaves it untouched; it is the drying wind, not the low reading, that browns and crisps the leaflet edges.
Humidity
Plain outdoor humidity is all it needs, so no level to hit. Air moving through the foliage counts more than moisture in the air, since crowded, still leaflets are where leaf spot and rust settle in.
Feeding
A single spring feed suits it. Use a balanced or acidifying shrub fertilizer, and shift to an acidic formula if the leaflets start to yellow from high-pH chlorosis.
Pruning
Prune after flowering to shape it or to cut a leggy, bare-stemmed plant back hard for fresh leaflets. Take out dead, damaged, or winter-browned stems at the same time, and pull the pale suckers as they surface to hold the colony in place.
Repotting
In the ground it never needs repotting, and in a pot it sits happily for years. Move it up only when roots circle the pot or the soil dries out far too fast.
Size & spacing
Expect a mature shrub 3 to 6 feet (91 to 183 cm) tall with a spread of 20 inches to 1.5 to 5 feet (51 to 152 cm) as the suckers thicken the base. Give it room to colonize, or trim the spreading edge back each year.
When to plant
Oregon grape moves through the year at its own pace. Plant it in spring or fall while the soil turns easily, look for the small yellow flowers to open in early spring, and watch the round blue-black berries deepen and ripen from late summer into early fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall
- Harvest: Yellow flowers in early spring; blue-black berries ripen by late summer to early fall
Hardiness
USDA hardiness zones: 5–8
Temperature: down to -29°C
Troubleshooting
Almost every problem with Oregon grape shows on the leaves, written across those glossy, spined leaflets, and most trace back to where it stands rather than any pest. Read the foliage closely and the cause is usually plain. Match what you see below, then fix the site before reaching for a spray.
Brown, scorched leaf edges that worsen over winter
When the leaflet margins dry to a papery brown and curl at the spined edge, that is winter leaf burn rather than disease. Bright winter sun and dry wind wick moisture from the glossy leaves faster than the frozen roots can push it back up, and a harsh summer exposure scorches them the same way. Move the shrub into partial to full shade with a windbreak, mulch and soak the ground before the cold sets in, and cut away the browned foliage in spring as fresh, green leaflets unfurl.
Fix:
- Site in partial to full shade with shelter from strong and drying winter wind
- Mulch and keep soil evenly moist going into winter
- Prune out badly burned foliage in spring as new growth emerges
Yellow leaves with veins that stay green
When a leaflet fades to pale yellow while a fine network of veins stays vivid green, that pattern is iron chlorosis, brought on by soil grown too alkaline for the roots to draw iron. A soil test names the cause. Elemental sulfur or an acidifying fertilizer pulls the pH down over time, and chelated iron brings the green back into the blades quickly.
Fix:
- Test soil pH
- Lower pH and acidify with elemental sulfur or an acidifying fertilizer
- Apply chelated iron for quick correction
Spots or orange rust pustules on the foliage
Sharp-edged spots or raised orange-to-brown pustules speckling the glossy blades are leaf spot and rust fungi, which settle on crowded plants held in humid, still air. Strip off the marked leaflets and bin them. Open the plant so air threads through the foliage and the surfaces dry after rain, and keep a labeled fungicide for the rare, severe outbreak.
Fix:
- Remove and dispose of affected leaves
- Improve air circulation and avoid overhead watering
- Apply a labeled fungicide if infection is severe
Toxicity
This is a gentle plant to keep close, though not entirely without edges. The cooked berries eat well, while the pale wood of the roots and stems holds berberine, a bitter compound that can upset a stomach if a pet or person swallows much of it. The stiff, spine-tipped leaflets do more day-to-day harm than the chemistry, so wear gloves when you handle it.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock
Safe for
People · Birds
Cats Mild
The pale inner wood of the roots and stems carries berberine, so a cat that gnaws through the bark may drool, vomit, or pass loose stools. A brush against a stiff, glossy leaflet comes to nothing; the upset needs a real mouthful of the woody tissue.
Dogs Mild
A dog that splinters the stems or chews the roots meets the same bitter berberine and can end up with a churning stomach and diarrhea. The more of the fibrous wood it swallows, the worse it runs, and most dogs recover on their own.
Horses Caution
Horses tend to shy from the spine-tipped, holly-like leaflets, but the berberine locked in the woody stems can still sour the gut if one grazes a quantity. Keeping the shrub beyond a horse's reach settles it.
Rabbits Caution
A rabbit is small enough that even a mouthful of the bitter, berberine-laced leaflets can unsettle its digestion. It does not belong in anything offered as forage.
Livestock Caution
Cattle, goats, and sheep usually turn from the rigid, prickly foliage, yet a real bite of stem or root could bring on mild digestive upset. Left to graze, they rarely single it out.
Birds Safe
Wild birds strip the plump, dusty blue-black berries clean and carry the small seeds off unharmed. Those fruits are one of the ways the shrub reaches fresh ground.
People Berries safe when cooked
The tart, dusky berries cook down into jelly or wine and are safe to eat that way, so the fruit is fine for people. The pale, bitter wood of the roots and stems is not, since the berberine in it upsets the stomach in any quantity.
The glossy, holly-like compound leaflets have stiff spine-tipped teeth that can prick or scratch skin; wear gloves and use care when pruning or handling.
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 gardens grow the straight species, but a couple of named selections stand out when space is tight or you want the yellow flowers laid on thicker.
'Compacta'
A low dwarf that tops out near 2 to 3 feet tall, its shorter stems packing the spined leaflets into a tight cushion good for close massing as groundcover.
'Apollo'
A low, spreading form that loads its dense, compact frame with a heavy crop of yellow flowers.
How to propagate
Oregon grape gives you three ways in, from quick to slow. Splitting the rooted suckers is the simplest, while stem cuttings and seed both make you wait for pale new roots to form.
Stem cuttingsModerate
Late fall to winter, after some cold exposure · Several weeks to months to root
Cut lengths of firm, half-ripened stem in late fall or winter once the wood has stiffened under some cold, and coat the raw ends with rooting hormone. Sink them into a moist, well-drained medium, where pale new roots push out slowly over several weeks to a few months.
DivisionEasy
Spring or fall · One growing season
Division is the direct route. The shrub throws pale stolons outward under the soil into a dense clump of suckers, so in spring or fall you can lift it, slice apart the already-rooted shoots, and reset them. Each rooted piece knits in over one growing season.
SeedModerate
Sow stratified seed in fall or after cold stratification · One or more years; seed is slow to germinate and reach size
Seed is the drawn-out route. Squeeze the small seeds free of the dark berry pulp and either sow in fall or chill them through a cold stratification, since they stay locked without that cold. The seedlings creep along for a year or more before they gain any size.
Myths
Oregon grape berries are poisonous because they look like holly or barberry fruit.
The small, dusty blue-black berries echo holly and barberry fruit closely enough to spark the fear. Raw, they are punishingly tart, but cooked into jelly or wine they turn good to eat, and the plant is listed as non-toxic to cats, dogs, and horses. The fruit is safe; only the pale, bitter wood of the roots and stems is worth keeping out of mouths.