Mahonia

Fundamental Facts

HARDINESS: Zones 5 to 8
PREFERRED SOIL pH: Slightly acid
PREFERRED SOIL TYPE: Fertile, moist, well-drained
PREFERRED LIGHT: Partial shade
ATTRIBUTES: Hollylike leaves, yellow flowers, blue berries; for beds, foundations
SEASON OF INTEREST: Year-round
FAVORITES: Oregon grape holly, leatherleaf mahonia, and their cultivars
QUIRKS: Very sensitive to sunburn and windburn
GOOD NEIGHBORS: Azalea, barberry, ferns, hosta, pachysandra, lamium, epimedium
WHERE IT GROWS BEST: Partial shade with wind protection
POTENTIAL PROBLEMS: Parched leaves from excessive sun
PRUNING: Lives many years; cut out oldest canes at ground level in winter
CRITTER RESISTANCE: Good
SOURCE: Nursery plants
DIMENSIONS: 3-8 ft (1-2.4 m) tall, 3-6 ft (1-1.8 m) wide

Mahonia in the Landscape

It is the beauty of mahonia's large, blue-green, hollylike leaves that makes this shrub so useful in the landscape. A group of mahonias, or a single one, flanked by azaleas or ferns makes a dramatic picture. And adding to this shrub's appeal are its early flowers and berries. Yellow flower clusters open in early spring, weeks ahead of daffodils, and develop over summer months into bunches of dark blue berries that persist until birds snap them up.

Mahonias perform best if you find a shady, sheltered spot where they won't be scorched by sun or whipped by winter winds. Place them along a house foundation, in front of a hedge, or near a wall where they'll receive a few hours of morning sun but shade from midday onward. Nestle these stiffly upright plants among other shrubs, such as barberry and camellia, or with shade-loving perennials, such as ferns and hostas. Mahonias are also stunning when under/planted with pachysandra, lamium, or other shade-tolerant groundcovers.

Mahonias Large and Small

The most popular species is Oregon grape holly (Mahonia aquifolium), native to the forests of the Pacific Northwest. Its new spring leaves have a reddish cast, and the bronze coloring often returns with winter's cold. Growing 3-5 ft (1-1.5 m) tall, this species spreads by underground stems into a broad clump. Yet it's far from invasive, and routine thinning of old canes in winter will maintain its size.

Lending a strong architectural presence to the landscape, leatherleaf mahonia (M. beolei) grows 8-10 ft (2.4-3 m) tall and about 6 ft (1.8 m) wide. Its large leaves, composed of 9-15 spined leaflets, often have a blue-green hue and are held at a stiffly horizontal angle from the stems.

Growing Mahonia

Plant container-grown plants in either fall or spring, in holes that are the same depth as the nursery containers but twice as wide. Enrich the soil in the hole with compost or leaf mold, set plants at the same depth at which they grew in their containers, fill in the hole, and water well. Mulch with a 2 in (5.1 cm) layer of shredded bark or pine needles to keep the soil moist. After their first season, mahonias become drought tolerant.

These tough plants have few pest or disease problems but may need pruning every other year to help maintain their vigor. In winter, lop off the oldest canes, cutting them close to the ground. You can remove up to one-third of the canes at a time. Never prune mahonia by cutting off the stem tips, or you will remove the best foliage along with flower buds and all chances of seeing fruit develop.