Italian Alder

Italian Alder (Alnus cordata) is the tree to plant when you need height quickly on a wet or exposed site. It grows to about 12m tall and 6m wide in a neat conical shape with a strong central leader, and it is one of very few fast screening trees that sits in damp ground. The glossy heart shaped leaves hold late into autumn, so the bare period is short.

Why you'll love it

• Height in a hurry. Fast growing and reliably upright, so a bare boundary reads as a treed one in a few seasons, not a decade.
• It copes with wet ground. Damp corners, dam edges and heavy clay that kill most trees are exactly where alders do their best work.
• And it copes with dry. Unusually for an alder, this one handles dry sites once established, which is why it turns up on exposed embankments and farm windbreaks.
• Upright and narrow. The conical form screens at height without a wide low crown taking over the bed underneath.

Where it works best

Screening and privacy. Plant 4m apart for a tall screen. Closer spacing crowds the crowns, pushes the canopy up and leaves a gap at eye level you cannot fix later.

Windbreaks. A staggered double row at 4m spacing filters wind across a paddock or an exposed boundary rather than blocking it.

Shade trees and avenues. Single trees give a high clean canopy along a driveway. Allow at least 6m from a building.

Growing Italian Alder in Australia

Position and climate. Full sun. It suits warm temperate, cool temperate and Mediterranean gardens, and it is frost hardy, so cold southern and tableland districts are well within range. It is not a tree for the wet tropics or for hot arid inland gardens.

Soil. Genuinely adaptable. Heavy clay, damp ground and poor soils all work, and it copes with drier sandy sites once the roots are down. It fixes its own nitrogen, so rich soil is unnecessary.

Water and feed. Deep soak twice a week through the first summer, then taper off. After two seasons it looks after itself except in extended drought. Feeding is rarely needed, though a light complete fertiliser in early spring helps on poor ground.

Pruning. Keep a single leader while the tree is young and remove any competing ones. Lift the lower branches over two or three winters for clearance, while the tree is bare and the structure is easy to read.

What to expect when it arrives

It is sold in one size, a 45 litre tree. That is semi advanced stock with a formed trunk and real height on day one. It will still need staking for its first year.

The tree is deciduous, so a winter delivery arrives bare or nearly bare. That is normal. Expect a metre or more of growth a year once established on a suitable site. Trees are delivered Australia wide, with delivery from $29.95, and advanced and large stock is freighted at cost. Every tree carries our 30 day healthy plant guarantee.

Plant care guides and related reading

• Compare options in fast growing privacy trees.
• For exposed sites, see plants for windbreaks.
• Browse the wider deciduous trees range.
• Our guide to the best fast growing screening trees.

Common questions

How far apart should I plant it for a screen?

Four metres apart in a single row. At that spacing the crowns meet without competing, and each tree keeps its lower branches instead of racing for light.

Will it really grow in wet soil?

Yes, and that is its main advantage over other fast screening trees. It tolerates ground that stays damp for long periods, though not permanent standing water over the root crown.

Does it drop its leaves?

Yes, it is deciduous. It holds its leaves late into autumn and comes back early in spring, so the bare window is shorter than with most deciduous trees.

How big will it actually get?

About 12m tall and 6m wide in a garden. On a deep, moist site it can go higher, so keep it well away from the house and overhead services.