Mahonia aquifolium
Oregon Grape, Oregon Holly Grape, Oregon Holly
Hardy range 4B to 8B
Height 4' to 6' / 1.20m to 1.80m
Spread 36" to 6' / 90cm to 1.80m
Growth rate Fast
Form Upright or erect
Exposure Full shade to full sun
Persistence Evergreen
Bloom Color Yellow
Bloom Time Spring
The flowers are fragrant and showy.
Environment
This plant tolerates some drought and some salt.
This plant will grow in dry soil.
Suitable soil is well-drained/loamy, sandy or clay.
The pH preference is an acidic to slightly alkaline (less than 6.8 to 7.7) soil.
Leaf Color Green
Fall Color No change in fall color
Culture Notes
With holly-like leaves, blue fruits, and striking yellow flowers, Oregon holly has much to offer in the landscape. Fruits are attractive and appear to be produced in more abundance in the western portion of the country (see fruit photograph from Oregon). Plants will grow in sun or shade but should be shaded in the winter to prevent the purplish leaves from browning. Transplanting is most successful with either potted or balled and burlapped plants. Oregon holly reaches 4 to 6 feet tall with an equal spread. Plants grow moderately fast, spreading by the suckering root system. This plant is considered mostly allergy free and causes little or no allergy problems in most people.
Cultivars include: `Compactum' - about 3 feet tall; `King's Ransom' - upright with bluish green leaves that turn bronze-red in winter, somewhat more tolerant of winter weather; `Mayan Strain' - dwarf with glossy leaves; `Repens' - can be used as a ground cover.
Planting and establishing shrubs
The most common cause of young plant failure is planting too deep. Plant the root ball no deeper than it was in the nursery. In most instances, the root flare zone (point where the top-most root in the root ball originates from the trunk) should be located just above the landscape soil surface. Sometimes plants come from the nursery with soil over the root flare. If there is soil over this area, scrape it off. The planting hole should be at least twice the width of the root ball, preferably wider. In all but exceptional circumstances where the soil is very poor, there is no need to incorporate anything into the backfill soil except the loosened soil that came out of the planting hole. Never place ANY soil over the root ball. If a row or grouping of plants is to be installed, excavating or loosening the soil in the entire bed and incorporating organic matter enhances root growth and establishment rate.
Weed suppression during establishment is essential. Apply a 3-inch thick layer of mulch around the plant to help control weed growth. Keep it at least 10 inches from the trunk. If you apply it over the root ball, apply only a one or two inch layer. This allows rainwater and air to easily enter the root ball and keeps the trunk dry. Placing mulch against the trunk or applying too thick a layer above the root ball can kill the plant by oxygen starvation, death of bark, stem and root diseases, prevention of hardening off for winter, vole and other rodent damage to the trunk, keeping soil too wet, or repelling water. Regular irrigation through the first growing season after planting encourages rapid root growth, which is essential for quick plant establishment.
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