There are lots of different organisations and projects that are active in tree planting at the moment – it’s an important investment in the future of our communities and the planet overall. More trees where they are needed is good news for everyone!
But different trees are suited to different locations and settings. The trees that tend to be planted in parks, woodland and green spaces – known as whips – are around 2-3 years old. While they are small and quite vulnerable, they are well suited to growing in green spaces surrounded by other trees of various ages. They are also often planted in groups to create a screen or as a measure to prevent flooding.
What's a whip?
You'll have seen these shorter, twiggy specimens being planted in parks, gardens, woodland, verges and roundabouts all over the place. They are easy to plant in large numbers, so when group tree planting events and volunteer days take place, this is the type of tree being planted.
By contrast, a street tree stands at 3-4 metres high, is between 7-10 years old, and has had a lot more care and attention lavished on it before it is planted.
This helps prepare the tree for the tough job that lies ahead: growing in the harsh environment of a street.
Because of its size, it needs to be planted by a tree expert, using specialist tools, equipment and techniques to give it the best possible start.
What makes a street tree?
Before leaving the nursery, each tree has undergone a long process of carefully controlled growth and development to get them ready for planting - and thriving - in their new urban environment. In most cases, they will already be 7 to 10 years old – often referred to by tree specialists as “instant impact” or semi-mature trees.
These street-ready trees have the potential to mature into strong specimens that will bring so many benefits to the area they’re planted in.
They therefore do cost more individually, but planting a more mature, sturdy tree means that its benefits are enjoyed sooner.
In this post, we’ll look at some of the stages and processes a street tree goes through before it is planted, to show just how much work goes into getting a tree ready for life in your street.
Raising a tree from seed
When growing trees to fit into the urban landscape, it’s not enough to simply allow a seed to germinate and grow the way it would in a forest.
Trees that self-seed are often varied in shape and form, and while this can be beautiful, it isn’t appropriate for an urban environment.
The constraints of urban streets mean that trees in these areas need to be smaller and grow in a uniform, predictable way. They need to have:
- A straight and strong stem
- The beginnings of a well-established branch system
- A strong root system.
To meet these requirements, expert growers in tree nurseries can apply a range of different techniques to control how each tree grows and prepare it for urban life. These include:
- regular pruning to encourage a uniform shape
- supporting with canes or stakes in its early stages of growth, so that a strong straight stem develops
- transplanting to ensure strong and healthy root development
- frequent watering – young trees need a lot of water to grow strong and healthy
- feeding to ensure it absorbs an optimum blend of nutrients
After all this care and tending over several years, the tree is then ready to be transported to its final planting site – the street of an eager but patiently waiting sponsor!
Nurturing and tending to the tree to this extent in its early years ensures that it will thrive in its final setting, bringing many decades of benefits to the area.
Giving nature a helping hand
Not all young trees are capable of growing vigorously and healthily, even if they are subjected to the nursery practices outlined above. These trees need expert intervention if they are to make the expected grade.
There are a number of ways in which nurseries manipulate and enhance the growth of trees:
- Budding and grafting
This involves taking a bud or small piece of the desired tree and attaching it to another young tree that can provide the healthy and strong root system necessary.
As the grafted material develops on its new host, the original plant is pruned with only the desired material remaining. It is then nurtured in a similar way as trees grown from seed.
Some street trees are raised from cuttings, which involves removing a part of the parent plant and encouraging it to produce a root system of its own.
A classic example of this is the London Plane tree. London Planes do not occur in nature and are the result of a cross between two parents: the oriental and the occidental plane. The only way the London Plane can be propagated in the nursery is by using cuttings.
Once a cutting has established its own root system, it is grown on in the same way as a seed raised tree.
- Genetically identical (clonal) trees
Some tree species do not occur in nature. Known as a ‘clonal’ selection, these trees are all genetically identical and have been bred at a nursery, normally through the ‘grafting’ technique described above. Each tree is derived from a single specimen to ensure uniformity.
Mountain Ash is one example of a clonal tree that is particularly good in urban areas.
We’ve outlined here just some of the processes that go on behind the scenes to shape and form a young street tree.
After going through so much development in its early years, each newly planted tree will still require careful attention if it’s to continue to thrive. It relies on us humans to water, prune, and protect it, but it will deliver so much in return over its lifetime.
Image credit: Lubomirkin