Evergreen Alder (Alnus jorullensis): complete guide

Overview

Alnus jorullensis, known as Evergreen alder, Mexican alder, or mount Jorullo alder, is a unique deciduous tree from Mexico and Central America. This is one of the few alder species that is nearly evergreen - leaves persist much longer than usual. This makes it striking in autumn and winter. As a nitrogen-fixer, this is a valuable tree for forest restoration in warmer climates.

Appearance and Growth

Evergreen alder reaches 15 to 25 metres with a straight trunk and lightly fissured grey bark. Leaves are lanceolate-acuminate, 7 to 15 centimetres long, dark green, and remain on the tree longer than relatives. In spring, the tree bears yellow-green male catkins. Female seeds form small, woody cones. The tree grows rapidly - 60 to 100 centimetres annually in good conditions. Foliage sometimes persists until January or February.

Ideal Location

Plant this tree in full sun to light shade. It tolerates warm locations well and can even grow in sunny, dry corners, though naturally it inhabits moister environments. In temperate southern Netherlands, Belgium and Rhineland, it grows well.

Soil

Evergreen alder thrives in moisture-retaining, well-draining soil. It can grow in acidic to neutral soils (pH 5.0 to 7.0). This tree fixes nitrogen, so it adds nutrition to poor soils. Add organic matter for better water-holding capacity. Good drainage is essential - wet feet cause rot.

Watering

During growing season, water regularly, especially in dry periods. This tree prefers moist soil. Once established, it tolerates longer dry periods, though it is not drought-tolerant. After heavy pruning, provide extra water.

Pruning

Evergreen alder tolerates pruning well. Remove dead, diseased or crossed branches. Shape the tree for better silhouette. Heavy pruning can be done during dormancy (December to February), though in temperate climates some growth may occur year-round.

Maintenance Calendar

March-April: Monitor growth, remove dead wood. May-June: Blooming, full growth. July-October: Summer maintenance pruning. November-February: Late foliage may persist, minimal activity.

Winter Hardiness

Evergreen alder is hardy to about -10 degC, meaning it grows well in southern Netherlands, Belgium, Rhineland-Palatinate and southern Germany. In severe winters, growth may retreat or be damaged, but the tree usually recovers. In very harsh years, young trees may die. This is not a tree for northern Netherlands or Poland.

Companion Plants

Use Evergreen alder in mixed woodlands and hedgerows in warmer zones. Combine with other southern deciduous trees. The semi-evergreen nature makes it interesting in autumn-winter gardens. Underplanting thrives thanks to nitrogen fixation.

Closing

Alnus jorullensis offers something unusual - an alder that retains foliage late in season. For warmer regions of Netherlands, Belgium and Germany, this is a valuable tree for forest plantings and landscape enhancement. Visit gardenworld.app for more information on trees for warmer climates.