Posted by Phytopath on Mar 16, 2010
Hedges can be an asset to the garden or they can be deleterious.
The positioning of your hedge or screen will determine which of the above effects will occur.
They can be formal or informal, or even semi-formal and they can range in height from 15cm (six inches) up to three metres (approx nine or ten feet).
A good question to ask your-self would be, “why do I want a hedge?” Perhaps you want a privacy screen from the nosey next door neighbour (visual pollution), or maybe you would like to create a micro climate in your garden so you can grow that special plant. Whatever the reason, the hedge or screen must serve a function, – it must be justified.
Hedges and screens have been used for borders and barriers, privacy, protection from wind, dust or airborne salt, for directing a view or screening a view and even to direct movement by restricting human and animal access. Whatever your reason for choosing to plant a hedge or screen there are some important criteria to consider when selecting the best plant.
First of all the plant must be tolerant of constant pruning and capable of quick rejuvenation. You don’t really want to wait three or four months for the plant to bush up again after pruning.
Next, the plant needs to be low branching with a dense habit and preferably have small leaves. It must be long lived with a moderate growth rate. (If you are thinking of building a maze, you certainly don’t want slow growing plants. People would cheat and step over the top instead of working their way out).
Ideally the plant would be resistant to pests and disease; there is nothing worse than a dead plant or two in the middle of your formal hedge.
The chosen plant must also be able to compete with its neighbours for light, water, nutrients and good root development.
The soil and climate are also important considerations when making your choice of plants.
Some of the limitations or disadvantages of formal hedges include the fact that they are labour intensive, there is significant root competition because of the close proximity of planting, odd plants may die out, leaving gaps and they can often take years to develop to the desired height and density.
On the positive side, screens have more flexibility (as opposed to hedges). They create a soft, natural appearance which is often times more pleasing than a fence. You can create a screen from mixed or single plant species, giving different results.
Chosen plants can be dense in their form or more open, giving a semi-permeable effect and reducing wind velocity. Plants other than small trees and shrubs can be considered. What about climbers on a trellis or containerised plants? Espaliers are also useful and they take up less ground space for the same or similar end result.
So why did I say that the planting position is important? Because if you get it wrong, instead of protecting your plants or garden a hedge or screen can funnel wind, hot or cold, and frost, right onto your desirable plants. Look at your site, know the wind directions all year round and if you are in an area with frost and you are trying to grow frost tender plants, watch the behaviour of the frost and notice where it settles. Frost tends to move much the same way as water does, that is, downhill. It will also build up behind a solid barrier.
Once you are sure that you have things under control (in your own mind at least) get on with the planting. The plant spacing should be approximately one fifth to one quarter of the mature width of the chosen plant and why not think about growing an edible hedge or screen for extra pleasure. Some all time favourites are: – rosemary, hyssop, lavender, dwarf myrtle and lilly pilly just to name a few. If you would like the botanical names just ask me.