Growth of a White Alder

Size and Form

• The white alder tree is a fast growing tree with a mature height of 50 to 75 feet. The tree spread ranges between 30 to 40 feet and is medium textured. The oval to pyramidal crown is moderately dense and symmetrical in shape. Mature white alder trees have numerous, straight trunks growing from a single clump. The slender, horizontal tree branches have weeping, pendulous tips.

Description

• Younger white alder tree has a smooth, gray to green bark that is mottled on the lower half. With maturity the bark becomes reddish brown and plated. The deciduous, dark green foliage develops lighter undersides during summer. The 2- to 4-inch long, alternate, simple leaves are oval to ovate shaped with finely serrated margins. Flowers bloom in the form of male and female, greenish yellow catkins ranging in length from 1 ¼ to 4 inches. The catkins grow in clusters on twig ends and get conelike and woody as they mature.

Growth Requirements

• Plant white alder in an area of full to partial sun. The tree adapts well to a range of well-drained, moist, clay, sand or loam. White alder also grows well in very wet soil and is tolerant of acidic or alkaline ground. The thin bark of the tree is easily susceptible to mechanical damage. The tree needs an open area for healthy root development. White alder is hardy in USDA Zones 8b to 11 and requires minimal pruning to keep in form.

Problems

• The tree is well resistant to disease but is prone to serious damage from infestation from the flatheaded borer, a close relative of the bronze birch borer. The bronze birch borer severely damages white barked birch tree in the eastern regions of the United States. To reduce chances of infestation, do not prune trees in spring when the beetles are in active flight. Prune and destroy infested tree areas between fall and March when the infestations are easy to detect.