The alder tree, Alnus glutinosa, is a deciduous British native tree in the birch family, which has rounded, bright green leaves and red-brown catkins. It grows to around 25m in height and is typically found in areas of damp ground, such as wet woodlands, marshes and the banks of streams and rivers. It makes an excellent garden tree, particularly for those with wetter-than-average soil, and can also be grown as a hedge. It's particularly useful for gardeners with poor soil, such as those with new-build gardens. Its roots fix nitrogen so it can tolerate, and even improve, soils that other trees couldn't grow in.
Alder is a fantastic tree for wildlife, being host to many moths, including the alder moth, which has a vibrant black-and-yellow striped caterpillar, and its seeds are eaten by birds. A short-lived tree, it's life expectancy is just 60 years.
Growing Alnus glutinosa
Grow alder in moist soil in full sun to partial shade. Water regularly until it becomes established. Due to its nitrogen-fixing capabilities, there's no need to fertilise alder.
Advice on buying Alnus glutinosa
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You can buy bareroot alder trees from November to March, or in pots throughout the year. Hedging whips are also available
Ensure you have the right growing conditions – alder tolerates a wide variety of soil types and will grow on poor soils, but it does best in a moist environment
Always check plants for signs of disease or damage before planting
Alnus is known for attracting bees, beneficial insects, birds, butterflies/moths and other pollinators. It is a caterpillar food plant, has nectar/pollen rich flowers, provides shelter and habitat and has seeds for birds.