If you want to create a suitable environment for a seating area, garden building, vegetable plot or other growing area in your outside space, understanding how wind, sun and water behave is crucial to success. High winds can be a problem for some sites. They can make it more challenging to create garden structures and limit the number of crops you are able to grow. They can also limit the potential for work and recreation in a given location. On larger sites, shelter belts may be required to control wind flow. But in gardens and on smaller properties, an effective windbreak hedge could be enough to increase the potential of your site and make it easier to achieve your goals.
A windbreak hedge is simply a barrier of small trees, shrubs and other plants that is positioned to break and disperse the wind. One important thing to consider when creating a windbreak is that the aim is not to stop the wind entirely, but rather to soften its force. If the break is too dense or solid, the wind can build up on the windward side and cause turbulence. Heat and humidity can rise on the inside of the windbreak and this can lead to more problems with pests and disease.
Positioning a Windbreak Hedge
It might sound obvious, but a windbreak hedge should always be positioned at a right angle to the prevailing wind direction on site. Surprisingly frequently, hedges are placed not with reference to the wind, but with reference to property boundaries. If your primary goal is wind breaking, try not to fall prey to this mistake.
A windbreak hedge that is around 2m tall can protect an area beyond it of around 60m (the ratio is around 1:30). It is also worthwhile remembering, however, that it will also reduce wind on the windward side for a distance of about 2-4 times its height. The wind will move upwards when it encounters the barrier before it drops back down again.
When positioning a new windbreak hedge, it is also important to consider the length of the hedge in relation to its height. As a general rule of thumb, the ratio of height to length should be around 1:10, so a windbreak hedge of 2m in height should ideally be no less than 20m long. While this is not always practicable, following this ratio will help to reduce turbulence around the ends of the windbreak. For shorter windbreak hedges, this turbulence may be something which you have to take into account.
Choosing Plants for Windbreak Hedges
From Patterns to Details
As with any planting scheme in a permaculture garden, the process of designing a windbreak hedge should begin with broader patterns before moving to details. Wind patterns are the most obvious pattern to decipher. But it is also important to think about patterns of sunlight. For example, you should not overlook the shade that will be cast by the windbreak hedge when determining its position, or the relation of new planting areas in relation to the new planting.
Single Element, Multiple Functions
Just as a garden or garden building has many uses, so too a windbreak hedge can and should serve multiple functions. In a permaculture system, a windbreak is never just a windbreak. It might provide firewood or wood for other uses, it may also be a place to forage fruits or other edibles. Furthermore, a shelter belt or windbreak hedge could also be of benefit as habitat and food source for a range of local wildlife. It is important to keep the different potential functions in mind when choosing the plants.
Choosing For Your Area
It is also, of course, important to choose plants that are suitable for your area. Clues may be garnered from observation around the area where you live. Other shelterbelts and hedges can often be found edging nearby gardens and farmland and can give you a sense of the species that will work best for a windbreak hedge in your area. Be sure to consider not only the general climate where you live, but also micro-climate conditions, the extremity of local winds, whether there is maritime exposure, and the soil conditions in which you will be planting.
Another thing to consider when choosing windbreak plants is that you should aim to enhance biodiversity as much as possible. The more plant species you include, the more beneficial interactions can develop, and the more resilient the system will be.
It is generally best to include a range of both evergreen and deciduous trees and/or shrubs. Evergreens will, of course, keep their leaves all year round and continue to serve as a buffer against strong winds. But too solid a barrier could be detrimental. The branches of deciduous trees and shrubs can still filter the wind in winter to a degree, and the leaves that fall from them will rot down on the soil and feed the system.
Preparing and Planting The Windbreak Hedge
The Structure of a Windbreak Hedge
In order to maximise a windbreak's capacity to lift and diffuse the wind, it is best to plant to create a triangular cross-section, with taller plants in the middle bounded on either side by lower growing plants. When planting, begin with the tallest central plants, before moving on to planting the lower growing species on either side.
Purchasing Bare Root Trees and Shrubs
The cheapest way to create a windbreak hedge is with bare root trees and shrubs. These are best purchased during the dormant period, between late autumn and early spring. Generally speaking, deep rooted plants are best for withstanding strong winds. You may also wish to choose swift growing species, so the wind break establishes more quickly.
Native species such as alder, hornbeam, hawthorn, hazel, blackthorn and elder can all be good choices in a mixed polyculture windbreak hedge, and these can be interspersed with evergreens like Berberis, and Pyracantha. You may also like to consider nitrogen fixing shrubs like gorse, sea buckthorn, or various Elaeagnus varieties.
Plant Spacing and Planting
Plant spacing is one of the most important factors in creating an effective windbreak hedge. Depending on the plants that are chosen, a spacing of 30-90cm between the main structural plants is generally considered to be optimal. After the primary plants have been placed, you can position smaller companion plants to either side and begin to form the optimal triangular shape.
Dig holes for each of the plants in your prepared, weed free location, and position these before firming the soil back around the roots. Mycorrhizal fungi incorporated into the planting holes can help trees and shrubs to become established. After planting, water well if the weather is dry, and add an organic mulch of compost or organic matter around your plants.
Gary Parker keeps the UK’s green construction heritage growing by creating high-quality round buildings using ancient, traditional methods.