Mahonia AQUIFOLIUM

Mahonia AQUIFOLIUM - Mahonia aquifolium, Oregon Grape, Berberis.

Mahonia is a genus of evergreen shrubs in the family Berberidaceae, comprising about 70 species and distributed across North and Central America, as well as East Asia.

Plants of this genus are evergreen shrubs with leathery leaves arranged in pinnately compound blades. Leaflets often have spiny-serrate margins, are dark green, glossy, and take on a reddish hue in winter. The bark is gray or brown, and the branches are spreading.

Flowering occurs in spring or autumn. The flowers are small, bright yellow, clustered in racemes or panicles. The fruits are blue-black berries with a glaucous waxy bloom, edible in certain species, ripening in summer or autumn.

Mahonia aquifolium is an evergreen shrub reaching one meter (3.3 ft) in height, forming fairly dense thickets through root suckers. The bark on young shoots is colored pinkish-gray, and on older ones brownish-gray. Alternate, compound imparipinnate leaf blades consist of 5-9 leathery leaflets with spinose-dentate margins. Leaf length can reach 20 cm (8 in). The leaves are dark green, glossy, and the petioles are reddish.

Multiflowered axillary racemes or panicles consist of bright flowers of a pale yellow color (sometimes with a lemony tint), whose diameter can reach 0.8 cm (0.3 in). Flowering occurs in April and May, while the berries ripen in September or August.

The fruits are oblong-elliptic berries colored blackish-blue; on their surface is a dense coating of glaucous bloom and fine fuzz. The berries reach 1 cm (0.4 in) in length and 0.8 cm (0.3 in) in width, possess a pleasant sweet-tart flavor, and are used in confectionery and for coloring wines.

Seeds are cleaned, dried, and sown directly into their permanent location. For spring sowing, mandatory stratification is conducted for four months at around 4 °C (39 °F). For autumn sowing, stratification occurs naturally. Seeds are sown onto moist substrate, lightly covered with soil, moistened from a spray bottle, covered with film, and germinated in light at 20-25 °C (68-77 °F).

Seedlings emerge in 4-8 weeks. Germination is accompanied by regular ventilation. Desiccation or waterlogging of sowings must not be allowed. Flowering of young plants occurs 4 years after sowing.

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This shade-tolerant plant exhibits high resistance to frost and drought, as well as low demands on soil. Cultivation in partial shade or light shade is recommended. When situated in the sun, shading during midday hours is provided. Indoors, diffuse lighting without direct sunlight is required. Basic care does not demand much time: watering, misting, fertilizing, pruning, soil care, and protection against diseases and pests.

In the warm season, a temperature of 18-26 °C (64-79 °F) is maintained. In winter, temperatures down to 5-8 °C (41-46 °F) are permissible. In the first years after planting, watering is done abundantly and regularly at the root and over the crown using a hose with a spray wand in the evening after sunset. Mature shrubs are watered in dry spells 2-3 times a week at 10 liters per bush. With regular precipitation, watering is not needed. After watering, shallow loosening of the soil is recommended.

A loose, well-drained substrate based on leaf mold, humus, and sand is used. Repotting or transplanting is performed in spring or summer by the pot-stepping method. Autumn transplanting is not recommended due to the risk of winter kill. Drainage is mandatory.

Twice per season, mineral fertilization is applied: in early March and mid-May, using Nitroammophoska or Fertika Lux (100 g per 1 sq. m). In autumn, a 5 cm (2 in) layer of humus or compost is added to the tree basin, which is dug into the soil in spring.

Sanitary pruning is carried out in early spring before bud break, removing damaged and dried branches. Formative pruning is done in autumn or right after flowering to shape a compact crown. Rejuvenating pruning is performed on mature shrubs to stimulate the growth of young shoots.

Young plants are sheltered for the winter with spruce boughs. Mature shrubs require shelter only in severe winters with little snow. Under snow cover, Mahonia endures frost without damage.