Mahonia aquifolium Oregon grape

Oregon grape or Oregon grape holly is an old-fashioned plant that is so easy to grow and that can turn into a jewel in your garden if you give it what it needs. We commonly see it in neglected cottage gardens where it does not often look its best, put in the silliest corner, just waiting for the autumn to be sheared like a sheep for the attractive evergreen leaves. It comes from North America (British Columbia to Oregon) and was named in honour of Bernard McMahon (1775-1816), a significant American nurseryman of Irish origin. It was first introduced as a garden plant in 1823 and our first Czech plant was planted only some 20 years later in 1844, in Královská obora (the Royal preserve, in existence from the Middle Ages) in Prague.

The species of Oregon grape is an evergreen shrub with leathery, deep green, highly glossy, pinnate leaves composed of holly-like leaflets with serrated or thorny leaf margins. In autumn when some of the leaves turn bright red and maroon if cultivated in a sunny location. These coloured leaves will fall off in spring and will be replaced, still, most of the leaves remain on the plant, unchanged, throughout the year.

In April, it makes short, raceme-like, upright panicles composed of thousands of small, sulphur-yellow, strongly scented flowers. They are followed by oval, blue berries in late summer. They are not poisonous, they are even classified as edible and were formerly used as a cheap substitute for true grapes in winemaking, and to dye real wine if its colour was too weak. The juice is not recommended for pregnant women.

Oregon grape makes upright, often twiggy or even leggy shrubs of versatile use – small specimens in front yards or combined with other shrubs or conifers in an evergreen border and is often used in mass plantings in parks where evergreen foliage is the key demand. It grows moderately and benefits from annual pruning that will secure a more handsome habit.

Oregon grape will tolerate almost anything but it will thrive in moist soil and filtered sunlight. For best results provide year-round mulching above its roots to retain moisture. This way it can cope with full sun, too, where it will exhibit the best habit. It will also grow in full shade. Pruning of any sort, even back pruning is possible after flowering and the plant will always look better rejuvenated. Occasional fertilizing will enhance its appearance but is not a must. The best soil is slightly acidic, well-drained, yet it proved to cope with much worse soil conditions – chalky or slightly clay with occasional waterlogging. Although it is generally not recommended for too dry locations such as arid street strips and heat-absorbing parking lots, it has been observed to handle occasional droughts and its roots have even resisted fires. Late frost doesn't harm its flowers at all, they can bloom and be covered with snow again. Fully hardy to min. -29 °C (USDA zone 5) and in protected habitats it can withstand down to -34 °C.

Last update 29-01-2019; 25-01-2023