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Grey Alder, Alnus incana, is a very hardy tree that loves wet sites and will thrive on poor soil if it is in full sun. It can be used in a rough country hedge, but we really recommend Italian Alder or Common Alder instead for use as hedging. Grey Alder tends to produce a thicket of suckering stems from the base of the tree that are good for supporting wildlife.
Grey Alder trees can reach 30 metres tall in ideal conditions, but 20-22 metres is more normal.
The plants on this page are young saplings, ideal for woodland planting projects. You can also buy larger Grey Alder trees and the ornamental variety, Alnus incana 'Aurea', either of which will give you more of an instant impact in a garden.
Browse all of our other Alder varieties here.
Grey Alder plants are only delivered bareroot, during winter (Nov-March).
Choosing a size:
When you are ordering Grey Alder, we generally recommend that you use plants that are graded at 40/60cms or 60/80cms, especially if you are using them for a hedge. They are cheaper than large plants, easier to handle and they will establish well in poor conditions. Use larger plants if you want a tall tree quickly.
All our sapling trees are measured by their height in centimetres above the ground (the roots aren't measured).
Spacing a Grey Alder hedge:
Plant Grey Alder hedging at 3 plants per metre, 33cms apart.
General description of Grey Alder plants:
Grey Alder is a very vigorous tree that will grow in any soil apart from chalk or very acidic peat. It needs plenty of sun and although it will grow on dry soil, it really prefers wet sites that are prone to waterlogging. Italian Alder is better for dry sites.
Grey Alder has silver-grey young leaves and shoots and the bark is also grey. It bears decorative, 10cm long, yellow-pink male catkins in early spring, alongside the green female cones, which mature by the autumn. The seed are wind borne, but some small birds will still snack on a few of them. This tree is very hardy and will grow in the coldest Scottish frost pockets or exposed hillsides.
The alders are pioneer species: they are quick to take advantage of open soil, quick to reach maturity and quick to die, by tree standards. After 90-100 years, Grey Alder's main trunk will begin to die back. If its lower stems are in the shade, the whole tree will die. This process is an essential part of woodland ecosystems and alders are often planted as companion trees for other, slower growing plants (like Oak) in forestry projects.
Note on Alder roots: Alder has invasive roots that can break old water pipes and damage the foundations of old buildings or walls. 30 metres away from vulnerable structures is a safe distance to plant Alder. New build, concrete foundations are not at risk.
History & uses of Alnus incana
Grey Alder is a European and Russian tree that was introduced to Britain in the 1700's
Alders are commonly used for improving sites with poor soil (such as closed rubbish dumps and former industrial zones) and helping to protect against soil erosion. Like other Alders, Grey Alder has fibrous roots that hold the soil together and release nitrogen for neighbouring plants to benefit from.
Grey alder wood isn't very strong or good to burn, but it is rot resistant and easy to carve. It is a traditional material for making clogs.