When it comes to placing trees in our school grounds, there are various planting methods we must follow to ensure their healthy, successful and rapid establishment.
In most schools, it is the grassy spaces and traditional sports fields which we want to enhance with small or large trees. Grass, however, is the major negative feature, being vigorous and greedy for water and nutrients – and will absorb all of these before allowing the tree any spare. On top of that, men with mowers and strimmers/weedeaters attempt to cut long grasses around the bases of newly planted trees, ensuring a long slow death by ring barking. For these reasons, many newly planted trees die in the first few years. So we must get rid of the grass around the establishing tree.
Two categories of planting
There are two distinct planting categories we are going to follow:
The specimen tree: this is a stand-alone tree which develops its own characteristic shape, it is usually planted as a one off, or as an avenue or grouping with space around it as found, for example, in an arboretum.
A grouping of trees: also known as a stand, or a thicket or a grove. In this situation the trees are closely grouped together, and the whole will grow together and form a shape similar to what we see in a woodland.
Next month we will look specifically at planting specimen trees. For this post, we are going to concentrate on the second method with particular regard for ensuring effective tree planting in schools:
How to plant a group of trees
1. Identify the area that you want to plant out, bearing in mind that it is interesting to have a pathway meandering through trees. Depending on available space this will be the corners of fields, and those areas around sports pitches and along boundaries.
2. Using bamboo canes and string, get your children/students to mark out the area allowing at least a 2m path – or one which is based on the width of the grass cutting contractors mower – as the trees establish, the grass can be easily kept short. This looks good, forms a contrast to the tree zone, and allows good walking access.
3. Once done, you will have islands of grass. Inside these, we will plant our trees at 1-2m spacings, and very occasionally we will leave a much larger spacing for a bundle planting (see further down in post). 1m spacings are closer than most other tree planting schemes, but in our schools, we want to give the impression of faster growth for children, it will allow them to get among the trees, and later, the trees can easily be thinned by cutting them to ground level.
What type of trees?
4. Always plant some evergreens among the native deciduous trees. These will add diversity, good nesting sites, and give all important winter structure – this is important as the majority of the school year takes place during winter.
5. It is preferential to plant pot grown trees at 4-5ft heights, a simple concept for children to grasp when digging a hole and subsequently, seeing their newly planted tree. However, smaller bare root trees are cheaper and may suit your school budget. Evergreens, which generally establish slower but grow faster once settled, will probably be around 1-2ft heights optimal planting size – anything larger and the tree will struggle for a couple of years.
Ensuring effective planting
6. Remove or kill off the grass around the base of the tree, and mulch to a minimum of 1 ft/30cms diameter. You can use cardboard (which is full of beneficial fungi) or old carpet (replace this after a year) with compost, greenwaste or straw to 3” on top, and give it all good soaking to settle it. Do not suffocate the stem of the tree, a tree breathes through its bark.
7. Grasses in between the trees can grow long and provide good habitat.
8.Give TLC twice a year for 10 minutes per tree, clear weeds and replace mulch.
Tree planting strategy
Group species together for more consistent growth; use more shrubby/smaller growing species on the edges to maximise woodland edge effect. There are no rules, so experiment and be unique!
This is an old technique for planting a number of trees closely together. Plant up to 7 trees in the same hole or plant up to 13 trees within 1-2ft spacings of each other. This will make an interesting feature among the mass planting. Allow 4-5 metres diameter space around this bundle feature.
Use western red cedar; or lawson cypress; you can plant leylandii but allow more space for this fast grower. If natives are required, use holly sparingly – its leaves can be very prickly even years after falling. Holm oak is good but spread it out, it grows very large. Smaller thicket type evergreens shrubs like Cotoneaster franchettii, below, are great for edge effect and winter berry colour (loved by birds and bees).
Read more about community woodlands here.
See also Post on Focus Project Berry Hill: March 2021
Next month: Effective Tree Planting in Schools 2: The Specimen Tree.