White Alder • Alnus rhombifolia
Growth Habit and Environment
White Alder is a deciduous tree that has the widest natural range of any other plant we offer. Found from British Columbia clear down to Baja Mexico, it will grow between 50 and 80 feet tall and 30 to 40 feet wide. Like it's coastal Red Alder cousin, White Alder has a unique relationship with nitrogen-fixing bacteria on it's root nodules. Because of this it can be a great centerpiece in a garden or landscape, helping to provide nutrients to companion plants and wildflowers. Commonly found in riparian areas, along streams, rivers, and in wetlands, it is well-adapted to moist, fertile soils and can tolerate periodic flooding.
Seasonal Cycle
As temperatures start to rise and daylight increases at the close of winter, white alder trees begin to emerge from dormancy. Male catkins develop and release pollen, which is carried by the wind to female catkins on the same tree or ones nearby.
When spring temperatures reach optimal levels, leaves will emerge and the fertilized female catkins will start to develop into cone-like structures. As the season continues into summer, these cones will slowly start to open as seeds are produced.
As Summer cools into Autumn, leaves turn a yellow color and fall off before winter arrives. Cones will be fully opened by late October, and seed dispersal occurs.
Planting Tips
Ideally planted in moist soils or along the edges of consistently wet zones like streambanks or irrigated areas, White Alders exhibit rapid growth to about 20 feet and gradually extend to 50 feet. Care should be exercised in selecting planting sites due to potentially invasive roots, and their larger size might render them unsuitable for compact residential gardens. Caution is advised to avoid interference with irrigation systems and foundations.
Consistent moisture coupled with sun to light shade is essential. White Alders play a pivotal role in it's environment by fixing nitrogen into the soil, serving as valuable agents of ecological restoration, and will provide much needed nitrogen to other garden plants and wildflowers.
Transform Your Outdoor Spaces
At Oregon Tree & Vine, we believe that beautiful gardens can transform any outdoor space. Our wide selection of native plants with their vibrant flowers, edible fruits, and lush foliage, will help you create the garden of your dreams. We are committed to providing our customers with the highest quality plants and exceptional service.
