Californian red alder (Alnus rubra)

Californian red alder (Alnus rubra) is a tree that can grow higher than 15m tall and 3m – 8m wide. In this growing guide we’ll learn the cultivation details and how to plant Californian red alder (Alnus rubra).

This plant has several common names including: Californian red alder, tag alder, Oregon alder or red alder.

This is a deciduous plant that takes 20-50 years to reach full maturity.

Plant profile

Common name: Californian red alder, tag alder, Oregon alder, red alder
Scientific name: Alnus rubra
Plant type: Trees
Habit: Columnar / Upright
Height: Higher than 15m
Spread: 3m – 8m
Foliage: Deciduous
Sunlight: Full Sun
Soil: Chalk, Clay, Loam, Sand
Moisture: Moist but well drained
Garden type: Architectural, Wildlife Gardens
Planting type: Hedging & Screens, Low Maintenance

Seasonal colors

How to plant Californian red alder (Alnus rubra) – brewbooks from near Seattle, USA, CC BY-SA 2.0, via Wikimedia Commons

Trees are essential plants in gardens, large and small, with their sculptural presence.

In terms of design, they add height, structure and interest all year round with attractive flowers, foliage, fruits and trunks.

In addition, they provide home and a food source for birds and other wildlife.

How to plant

In this section we will learn how to plant Californian red alder (Alnus rubra), know its needs in terms of soil, watering and sun exposure.

Soil

Californian red alder (Alnus rubra) is a plant that adapts to all types of soils, chalk, clay, loam or sand.

• The chalky soil is pale and contains chunks of calcium-rich rock. It is a fertile and well-draining soil, almost always alkaline.

• Clay soil is composed of more than 25 percent clay particles. These particles have a high moisture holding capacity and the soil is heavy to dig and can be waterlogged in winter (dry in summer).

• The loam soil is dark, rich in organic matter but balanced in minerals. It offers the best of all worlds, retaining enough water for the plants, but allowing excess moisture to drain away. This is the most desired type of garden soil, perfect for most plants.

• Sandy soil is light, porous and very easy to drain. It is a soil poor in organic matter and nutrients. It is composed of relatively large mineral particles that allow water to drain quickly.

It is not very sensitive to soil acidity or alkalinity and grows well in soils with pH acid, alkaline or neutral.

Regarding drainage, Alnus rubra likes to grow in moist but well drained soil.

Sunlight

Californian red alder (Alnus rubra) should be grown in full sun places.

Cultivation profiles – Growing Californian red alder (Alnus rubra) – image source