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The Toorak Gum Tree or Evergreen Silver Birch is a selected variety of Evergreen Alder (Alnus jorullensis), also known as Mexican Alder. It is a fast growing, hardy evergreen tree. It was Melbourne’s most popular tree in the 1970s, but misunderstood and with it’s best features underappreciated, it then passed into relative obscurity. Hello Hello Plants founder Chris has always had a love for the Evergreen Alder tree since he first helped his father collect the seed from a rare tree nursery, and he thinks it’s due for a comeback.
Features of the Evergreen Alder (Toorak Gum Tree)
The Evergreen Alder (Alnus jorullensis) has many very useful qualities that can be put to great advantage:
Fast Growing
First benefit of the Toorak Gum Tree is amazing growth speed. If you plant a small seedling, say 50 or 60 centimetres tall, keep it free of grass and weeds at the base, keep it well watered and lightly fertilised, it’s capable of growing up to five metres in one year.
Their requirements for fast growth are simple: they hate grass around their base, so need to be kept grass and weed free. They need some water during the dry months and give them just very, very small regular doses of fertiliser and they grow like crazy.
Poor Soil
If watered and fertilised with a slow release fertiliser like Osmocote, the Evergreen Alder will flourish and thrive in the most difficult soils. They can thrive in the heaviest clay, even in spots where excavation has been done and there is only infertile subsoil left. Around the world, various varieties of Alders have actually been used to regenerate old mine sites for this reason.
Boggy, Waterlogged Soil & Flooding
The Toorak Gum Tree (Alnus) is flooding and wet feet tolerant, and actually love to be flooded every so often. They do well in locations where conifers or other trees would die from wet feet (root rot). And because Evergreen Alders are evergreen, they’re good at taking up excess moisture during the winter when other trees such as willows are dormant and not taking up moisture at all.
Fire Resistant and more
Evergreen Alders are also fire resistant and they resist burning and can be used on the northern side of houses and shedding to slow or resist bushfire onslaught. They are frost tolerant.
Uses of Evergreen Alder trees
Wind Breaks, Hedges & Screens
Fast growth makes Evergreen Alders great as wind breaks because they can be quickly established, and are very wind hardy. They can also act as a frost screen. Being evergreen they keep their leaves all year round, and have lovely foliage that looks like Silver Birch but never turns yellow and drops off. This is why they were once marketed as the “Evergreen Silver Birch”.
Evergreen alders are able to be hedged or trimmed or pleached, and respond very well to trimming. They can be kept quite short and narrow with a regular prune, and they tend to have a straight central leader (top stem) and trunk. With the bottom branches removed and the sides and top trimmed, they lend themselves to making a very hardy pleached hedge.
Nurse & Barrier Trees
A nurse tree is one that is planted with other smaller or important plants such as crops, to provide protection, shelter and other benefits. Because they are one of a special class of plants that add nitrogen to the soil rather than using it up (called nitrogen fixing), they actually help to feed other trees and surrounding plants.
For this reason Evergreen Alders make excellent nurse or barrier trees, planted around an area designated for more vulnerable plants, including an ornamental garden. In their homeland of South America, they are planted between fields by coffee farmers for this exact reason.
Rural Properties & Gardens
Evergreen Alders are very useful for establishing a garden on a rural property. Often these sites have poor soil (heavy clay in a lot of Victoria, which the Alnus loves) and are very exposed. When Chris is doing rural garden designs, often they have to be planned and planted in two stages. First, plants to provide shelter from winds and sun are established in strategic spots, and then the more delicate ornamental plants come later.
Evergreen Alders grow rapidly if given access to water, and this means they are one of the fastest ways to establish a protective windbreak or screen for the rest of the garden. As they grow so fast, there are situations where they can be put in at the same time as other plants, getting rid of the need to wait to get the rest of the garden done.
Invasive roots
Because the Alnus is a fast growing water lover, it can have an aggressive root system. This means you need to be careful not to plant them in spots where this could be a problem, such as close to house foundations or right next to pathways and paving.
Evergreen Alder planting & care
Evergreen Alders will grow about 8 metres tall and 4 to 5 metres wide, but they love to be trimmed and can be kept at almost any height. If you want a neat hedge shaped screen, trim them 3 times a year, or if you just want to keep the trees small trim them once a year. The time of year for the trimming doesn’t matter – do it whenever you feel like.
If you’re planting a screen you plant them 2-3 metres a part. For an avenue plant them 6 to 7 metres apart.
Toorak Gum tree history in Melbourne
The Evergreen Alder or Toorak ‘Gum Tree’ Alnus (Alnus jorullensis) was first marketed in the early 70’s as the Evergreen Silver Birch. The Toorak ‘Gum Tree’ Alnus quickly became Melbourne’s most popular evergreen tree at that time.
It was easy to grow, it grew 6-9ft per year for the first few years and had cascading fine foliage, just like a silver birch. The suburb where they became most popular was Toorak. In Toorak, households planted them on nature strips and planted them in front yards and as screening trees up the side of houses. Unfortunately because they were a new product, people didn’t know how big the Toorak ‘Gum Tree’ Alnus would grow, nor did they know how easily the Toorak ‘Gum Tree’ Alnus could be shaped and pruned. This lead to people planting large numbers of Toorak ‘Gum Tree’ Alnus in inappropriate situations.
They were allowed to grow, without pruning, to their full size, often with several trees planted into courtyards or tiny gardens. A full sized Toorak ‘Gum Tree’ Alnus, as with any trees, can create problems when planted in the wrong spot. The inappropriate planting and management of the Toorak ‘Gum Tree’ Alnus gave the tree a bad name and created a Toorak ‘Gum Tree’ Alnus backlash.
In spite of the backlash the Evergreen Alder or Toorak ‘Gum Tree’ Alnus, Alnus jorulensis are still one of the top selling evergreen trees as they grow in any soil, even waterlogged, heavy clay and subsoil and if they are kept grass free around their base, well watered and fertilised they are capable of growing 9ft per year for the first few years.
These days gardeners are learning that if Toorak ‘Gum Tree’ Alnus’ are pleached or pruned to contain their overall size this prevents them from developing oversized trunks and root systems. Toorak ‘Gum Tree’ Alnus love to be trimmed. The harder you cut them the branchier and bushier they become, creating a dense screen.
At Hello Hello Plants we can access a supply of Toorak ‘Gum Tree’ Alnus, and that’s because one day each year we go to the leafy streets of Toorak and collects the ripe seed pods from the best looking Toorak ‘Gum Tree’ Alnus’ surrounding some of the best homes in Melbourne. It normally take 5 or 6 hours to pick enough seed pods to grow a years supply of Toorak ‘Gum Tree’ Alnus.
Chris likes to pick them himself as good seed selection is critical in controlling the quality of the trees. Also Chris enjoys his day out in Melbourne’s leafiest suburb, as picking seed has been a tradition of Chris’ for nearly 30 years.
So if you’re looking for an economically priced fast growing hardy tree that loves to be controlled, consider ordering a Toorak ‘Gum Tree’ Alnus or two.
Evergreen Alders Now for Sale
Hello Hello Plants is an online plant superstore based in Melbourne, Australia. We maintain our own fleet so we can deliver door-to-door all over Victoria. We stock a select range of the plants you see online at our physical retail nursery in Campbellfield (sadly they can’t all fit). We offer a one-on-one garden design service, and our resident garden guru Chris has over 60 years experience in the plant word and is passionate about educating people on plants & gardening.
