By Hosea Omole
Kenya: A hedge is a barrier composed of identical, tightly spaced woody plant material. It is a “living fence” or a “wall of greenery”.
It could be lofty or low in height, regularly trimmed or left natural. Whichever the case, hedges have wide applications in landscape design.
Originally conceived as defence against human intrusion or livestock barriers, early hedges featured dense and thorny plants with little aesthetic considerations.
Today, most hedge installations are far less threatening in their appearance and are planted in gardens as attractive visual obstructions to provide privacy, restrict casual trespassing or emphasise the enclosure details of a formal design.
They can also be used to provide an architectural frame or a backdrop for important landscape features such as statuary or a fountain. Here are a few things to consider:
Planting
Planting is done by preparing a continuous trench, not individual plant pits. Plants ordered from the nursery will inevitably have some variations in height and spread.
Trenches allow for easier on-site adjustments for a more even growth. The ideal spacing depends on the intended need for the hedge, the type of plant chosen and certainly the initial purchase size.
An often-used rule of spacing is to have the individual plants just touching if you need an immediate effect, but you may want to take into account the typical annual growth rate along with the expected mature size of the selected plant.
Hedges planted within the root zone of large trees often don’t do too well. As expected, a mass of established tree roots collects most of the available soil water and nutrients within its growing range and introducing a long line of hedge plants to this area will handicap the introduced hedge but not the tree.
The tree also provides some shading of the hedge for several hours each day. It is better to erect a fence under this condition.
Trimming
When trimming and shaping a hedge into a formally pruned line, you should take into account that adequate sunlight must consistently reach the oldest and lowest branches if they are to remain dense and attractive.
You can accomplish this simply by tapering the outside portions to provide a slightly wider bottom than top.
Shearing and pruning should be done when the plants are well established. Such pruning involves halting the terminal or upward growth in order to stimulate the axillary or side buds to expand and create fuller density. Thereafter, the trimming schedule will be determined by the local growth rate and the amount of desired neatness.
Rejuvenation
Hedges will require occasional rejuvenation to keep them bushy for a longer time. This is done by cutting down their stems so that fresh new stems can re-sprout and begin a new cycle of growth.
Over-aged evergreens rarely take kindly to this kind of severe pruning. Remaining stems typically struggle to re-sprout. Complete rejuvenation in a short time may be impossible or erratic. You are better off ripping out the old and bringing in a new hedge altogether.
With deciduous plants, drastic pruning for renewal is often workable, depending, as always, on the type of plant involved, since these plant types tend to replenish lost stems and growth buds far more easily than evergreens.
Yet, here too, aged plants may not be worth such rejuvenation given the somewhat unclear results.
— The writer is a landscape architect
