Oregon Grape Growing Profile

Mahonia aquifolium

blue mahonia berries and leaves
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The Oregon grape (Mahonia aquifolium) is a broadleaf evergreen shrub that grows well in shadier spots. It originated in western North America and is the state flower of Oregon. It will provide color throughout all four seasons with its green (spring) and burgundy (fall) foliage, yellow flowers, and purplish-blue fruit.

Latin Name

The name assigned to this species is Mahonia aquifolium and it is included in the Berberidaceae family.

Some botanists believe this should be placed in the Berberis (barberry) genus. Even though the common names suggest a connection, this is not a true grape (Vitis) or in the Vitaceae (grape) family.

The genus name of Mahonia was given to honor American horticulturist Bernard McMahon. Additionally,  aquifolium means that the leaves are like those of holly trees and shrubs  (Ilex), though they are in a different family.

Common Names

There are many different names that are associated with this plant. They are Oregon grape, Oregon grape-holly, Oregon-grape, Oregongrape, mountain grape, Oregon hollygrape, holly-leaved barberry, tall mahonia, Oregon grapeholly and Oregon holly-grape.

Many of these names are also used for other species of Mahonia, so specify that you want M. aquifolium to help avoid confusion.

Preferred USDA Hardiness Zones 

This shrub is best suited for USDA Zones 5-9. It is native to western North America.

Size

Oregon grape will be 3 to 10 feet tall and 2 to 5 feet wide.

Exposure

Partial shade is ideal for this species. It can also be grown in full shade or full sun, though too much light can cause foliage scorching.

Foliage/Flowers/Fruit

The evergreen leaves are sharply toothed like members of the holly genus as noted in the species name.

These are actually pinnately compound leaves that are up to 12" long and made up of several leaflets.When they first appear, they are red. As time passes they turn into a shiny green hue. During autumn they become burgundy but do not fall off.

In April and May clusters of cheery yellow flowers appear.

The fruit is a berry that does resemble a grape in shape and color. They are edible but are quite tart and can be used to make jams, jellies, and preserves.

Design Tips

If you want a similar looking shrub that is more of a groundcover, choose the creeping mahonia (Mahonia repens)This species only is about a foot tall at maturity.

Oregon grape can be used as part of a wildlife garden to attract butterflies, bees, hummingbirds, and other birds to your yard.

Look for the 'Compactum' cultivar if you want a shrub that is shorter (3 feet tall) than the species.

It can be used as a privacy screen to keep unwanted visitors out since the leaves are sharp.

This shrub can clone itself and spread. On one hand, this can be a useful feature as you can use it to populate a native garden or divide to create new plants. However, this tendency can also lead to the species being invasive in some locations. Your local extension service will know if it is a problem in your area.

Growing Tips

The soil needs to be moist with good drainage for optimal growth. It needs to be acidic or at least neutral as alkaline soils can be problematic. Change your soil to be more acidic if the pH is not too much above neutral.

Propagation can be performed through the use of seed germination, taking cuttings, and dividing existing plants. The plant will also naturally propagate itself through cloning.

Try to find a planting location that offers some shelter from the wind. Since these are evergreen and do not drop in the fall, the leaves may dry out in the winter if the shrub is hit by wind often.

Maintenance/Pruning

The Oregon grape does tend to form suckers, so pruning can be used to control these to some extent. It is quite tolerant of pruning and can even be cut all the way down to the ground if you want to give it a fresh start, but usually is not in need of much trimming.

Pruning should be done in spring once the shrub is done blooming.

Pests

On this plant, you may find signs of whiteflies, aphids, or scales. These insects are all likely to leave honeydew, which can lead to sooty mold.

Diseases

If your planting site receives too much sunlight, the leaves may become scorched. They may also develop chlorosis if placed in alkaline soil. You can sometimes see rusts or leaf spots develop on this shrub.