How are Mature Pleached Trees made?
Mature Pleached trees or screen trees start life as a seedling or cutting, much like any other tree, being repotted or replanted a number of times in their formative years. They grow happily on the nursery with hundreds or even thousands of other trees. When the time is right, highly skilled nurserymen and woman go out into the field with tags in hand and pick the very best trees suitable to pleach. Criteria for choosing the best trees for training includes selecting those with the straightest stems, healthy root stock and appropriately spreading and uninform crowns. Once tagged and lifted the trees are loaded onto trailers and sent to potting sheds for training.
Training is usually performed best with a team of two or three skilled nurserymen. The first job is to clear the stems of all foliage to a predetermined height – Popular ‘clean stem’ heights include 120cm, 150cm 160cm, 180cm, 200cm and 210cm – determined by the average height of walls and fences.
Pleached trees are available with stems heights outside these sizes (from full screens with 30cm stems to tall screens starting at 230cm or more), but in the main the above ‘clean stem’ sizes are the most popular. Once the stems are cleared, a premade bamboo frame is placed face down on the training table. A tree is laid over the frame with the stem positioned over the midpoint of the frame. The bottom of the frame is positioned in line with the lowest branches. Now the stem is attached securely to the center of the frame. Next the branches are carefully manipulated one by one and tied to the frame using a soft expandable tying material, creating a lattice work of branches covering the screen. When training is complete, the trees are checked for quality before being returned to the field, where they develop for between 1 and 5 years on average. Each new season fresh growth is tied to the frame or trimmed away, creating a screen which will measure approximately 30-40cm in depth after 3 years of training (slower growing varieties such as Taxus can take longer to develop). Once the crown is full and it has taken on a definitive square shape, tying in all but stops, with a light trim once or twice a year being the only maintenance required to keep the trees looking in tip top condition. A tree trained for 1 season (1 year) will have a relatively full screen but it will have little density. A tree trained for 5 seasons (5 years) will cover the frame entirely and measure roughly 30-40cm in depth or more. A 5 year pleached tree will command a higher price than a pleached tree trained for 1 year.
Hedgeworx pleached trees are available for sale with training from 1 year to 5 years and in some instances much longer. We have sold trees in the past which have been trained for over 12 years. Please enquire about these older specimens.
Frame width and height is usually determined by the size of the tree being pleached i.e. what size frame is the tree capable of supporting. Typically frame widths vary from between 120cm wide (young trees) to 220cm wide (older trees). The height of frames varies considerably more. In some species frames start at just 30cm above ground level while in others they may only start at 200 or 210cm above ground level for example.
Perhaps one of the main reasons canopies on older trees do not exceed 220cm wide is due to the size of delivery vehicles. More specifically the internal width of a lorry. The internal width of a curtain sided articulated lorry trailer is 2490mm. Trees any wider than this need vehicles with wide load capabilities.
Bamboo is by far the most widely used material for pleached frame work. The advantage bamboo has over all other material is it has a high compressive and tensile strength, it is light weight, easily available and therefore cost effective. Being a natural product, it is also better for the environment.
Bamboo quickly turns a silvery/grey colour after a few weeks of being outdoors, blending in with the foliage and branches it supports. Finished frames can be easily alerted if necessary and damaged sections replaced with a new piece of cane by a novice gardener. Bamboo does deteriorate over time, but this takes many years and it always outlasts its usefulness. In our experience a disintegrating frame is a sure sign it has finished its job and the time has come to remove it all together. Our frames vary in size from 120x120cm all the way up to 220x600cm. It is important to note that while frame sizes dictate the size of the screen, the branches and foliage can often
fall outside this area making the screen wider and taller than the frame itself. It is always worth asking what size the screen is (the screen being the actual box size made by the branches) as well as the frame size, as the two can vary quite significantly. With mature pleached trees the important measurement is the screen size, not the frame size.
Pleaching for deciduous trees
This tends to take place in the winter months as rootballed trees are used in most cases. Deciduous rootball stock is only available between the months of November and April when the sap flow is low, and the trees can be lifted out of the ground. The benefit of training deciduous trees in the winter months is they are free of leaves making the pleaching process of tying the horizontal branches onto the bamboo frame easier and the overall result is neater too. The reduced sap flow allows the young tree to recover more easily and the trees are less stressed as a result. The ancient art of hedge laying is undertaken in the winter months for this very reason. The best deciduous pleached trees – Mature or Fresh, are made in the winter months from November to April – insist on the best!
A much larger proportion of evergreen trees are pleached using plants reared in pots. This is really the only noticeable difference between deciduous and evergreen pleaching. The training techniques are much the same. Evergreen pleached trees and espalier trees are more readily available for year-round sale as a result.