Alder Trees

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Alders are fast-growing deciduous trees that thrive on and improve poor soil. Most varieties develop tall, conical canopies.
Their roots quickly bind loose or rocky earth, and they grow in waterlogged conditions that most other trees can't handle.
They require plenty of sun to thrive.

Alders produce distinctive catkins (the male flower) that can be dusty yellow, vividly green, or pink, and green female flowers that resemble small, undeveloped pinecones.

What size Alder trees should I buy?

If you are not in a hurry to get a full sized alder tree, we recommend starting with the smaller 6/8cm girth size.
If you are in a hurry and need instant impact, then go for the 8/10cm girth size.

Standard trees are measured by their girth 1 metre above the ground, and young saplings are measured by height.
So, a 6/8cm Standard Alder tree is much bigger than a 60/80cm Alder sapling tree or hedge plant.
If a tree is available in both sizes, it will be noted in the product description.

Browse our other garden trees in standard sizes.

Your Alder trees are delivered by mail order, along with expert advice, friendly support, plus our bareroot Replacement Guarantee, so you can give them a whirl with complete confidence.

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FAQs

Alder trees will grow in almost any condition, from boggy lakesides to dry slopes. Their roots fix nitrogen, which fuels their rapid growth and helps them to thrive in very poor soils.

The wild species are classic pioneer trees that rapidly colonise exposed, sunny locations, grow vigorously, and then the main trunk begins to break apart by the age of about 100 years. In most cases, the tree lives on through its prolific suckers.

Which Alder Species should I Choose?

Common Alder (which is native) and Italian Alder are the largest species, up to 25-30 metres; Italian Alder saplings are also suitable for rough, country style hedges and makes an outstanding windbreak.
Red Alder can get pretty big too, over 20 metres in the UK.

Grey Alder is very vigorous but has a smaller final size, around 15-20 metres, and tends to produce a thicket of suckering stems: great for wildlife, but not ideal in your lawn!
However, its cultivar Aurea is slower growing, smaller, reaching under 12 metres, more slender and stands out with its bright yellow-green leaves, making it suitable for most gardens.

Where can I grow Alder Trees?

You can grow Alder trees almost anywhere in full sun. They even thrive in waterlogged soil where few trees apart from Willow, Poplar, and Hazel will grow.
However, they also grow well in dry, rocky slopes, and are recommended for preventing soil erosion.
They are exceptionally versatile because their roots fix nitrogen, essentially fertilising themselves.

Most of them will grow quite close to the sea, but they need deep, reasonably soil to be wind resistant. They can certainly grow in poor, sandy soils, but mature trees growing in them tend to blow over in sea gales.

Note: Alders 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.

How tall do Alder trees grow?

Common Alder up to 25-30 metres
Italian Alder up to 25 metres
Red Alder a bit over 20 metres (in the UK)
Grey Alder up to 15-20 metres
Grey Alder Aurea up to 12 metres (does not produce root suckers)

When and How do I plant Alder Trees?

Alder trees are only delivered and planted bareroot during late Autumn to early Spring, from November to March.

This is the best time to plant any tree, because bareroot trees are cheaper, easier to carry and plant, and tend to establish even better than their pot grown equivalents.

Watch our Tree Planting Video for instructions.
Although optional, we strongly recommend using Rootgrow.

Aftercare:

Remember: the two biggest killers of recently transplanted trees are underwatering, and being choked by weeds and grass.

Regular, thorough watering is vital during dry weather in their first spring and summer, and highly recommended the following summer, especially if there is a heat wave.
In the case of Alder, it is not possible to overwater.
Either remove weeds and grass by hand periodically, or use some form of mulch to suppress them.

Tree Planting Accessories

Standards that are 6/8cm in girth and upwards are quite big trees, so they need a tree planting stake and a tree tie (with a buffer between the tree and the stake) during their first couple of years.

A mulch mat is will suppress weeds & grass, and preserve moisture: remember that dry soil and competition with weeds are the two biggest killers of new trees.
Even with a mat, you should remove anything that manages to grow up between the mat and the trunk in late spring and summer.

You can buy those items separately, or save money with our Tree Planting Pack.

You definitely need a tree guard if there are deer or rabbits about.
In urban areas with no wild animals, tree guards are great for protecting against mowers and strimmers.
For that purpose, you can cut one tree guard into several pieces about 20-25cm long, to act as skirting around the base of the tree.

Mycorrhizal Fungi

We cannot recommend using Rootgrow fungi enough: it makes a huge difference, especially with larger trees, which are scrambling to regrow the root systems that they lost when we dug them up, in order to support their now top-heavy growth above ground.

Mycorrhizal fungi assist the roots in accessing soil nutrients and water, and protect the roots from soil critters.
In return, the tree shares sugar with them, and the result can be over 50% more growth above ground!