Alnus cordata, are very vigorous in the right conditions and young trees can grow up a metre a year once they have established. These are tidy trees with a fairly narrow canopy, tapering to a point at the top. Their glossy leaves look lovely in the sun and are among the last to fall in Autumn. In early spring they produce round female cones and long yellow male catkins, which provide pollen for bees, although the wind does most of the pollination. They are superb windbreak trees. Italian Alder is soil tolerant - it prefers wet (heavy, damp clay is best), but it will grow on dry, chalky terrain too. None of the Alders like full shade but you can plant young trees in partial shade if they will grow up into full sun.
The Alder family are nitrogen fixing trees: they increase soil fertility by releasing water-soluble nitrogen-based compounds from bacteria that live on their roots. This means that they are great for growing on really poor soil and can be interplanted with slower growing species to provide shelter & improve the soil for them. Their matted, fibrous roots are also very effective at holding loose or rocky soil together and helping to prevent erosion on river banks. Note on Alder roots: Alder have invasive roots that can break old water pipes and damage the foundations of old buildings or walls. 15 metres away from vulnerable structures is a safe distance to plant Alder. New build, concrete foundations are not at risk. Italian Alder will usually grow to 20-25 metres tall: in ideal situations, with full sun and rich clay soil, it can grow to 30 metres.
How Standard Trees are Measured: All our standards, are graded by their girth in centimetres 1 metre above ground level (basically, their trunk's waist measurement). They aren't measured by their height, which will vary. So, a 6/8 standard has a trunk with a circumference of 6-8 centimetres and an 8/10 standard has a trunk 8-10 centimetres around. This measurement makes no difference to the tree's final height. Standard trees are 2.5 - 4.5 metres tall (on average) when they arrive; they are the most mature trees that you can buy from us.
History & uses of Alnus cordata: This tree was imported to Britain from Corsica and Italy in 1820. It is very resistant to rot - the piles that support Venice are made from Italian Alder