How to create a hedge
Hedges are groups of plants, generally with dense growth habits, which are grown in a row. Hedges can be made up of a single type of plant or many different species.
There are various different reasons for planting a hedge, and these will influence the type of hedge grown:
Hedges make fantastic windbreaks, which are useful in most gardens but particularly those in exposed locations. The wind is slowed and filtered by the hedge rather than being stopped by a solid wall or fence, which could create turbulence on the other side (solving one problem but creating another). Ideally a hedge should allow about 50% of the wind to pass through it. This will reduce windspeed by 50%, if you’re up to 7.5m away from the leeward side of a 1.5m hedge, and still reduce windspeed by 10% when you’re 30m away. So a hedge can provide shelter for plants both close to it and quite some distance from it.
The amount of shelter provided will depend on the type of hedge you have and how you grow it. Deciduous plants (such as Fagus sylvatica) will provide significantly less shelter in the winter compared to an evergreen hedge. The more rows of the plant you include in the hedge, the less wind will pass through it. The higher the hedge, the greater the area of protection.
Hedging can provide a useful screen within the design of your garden. This may be required to hide an unattractive feature (such as an oil tank), form a boundary to a neighbour’s garden, or create different areas or ‘rooms’ within the garden. Hedges with thorns can provide additional security to a boundary. Low hedging can also be used to line paths or border edges, while high hedges provide secretive corridors or mazes to walk through.
As well as stopping wind, hedges can also contribute to noise reduction, for example if you live near a road or railway line. As with the provision of shelter, the denser hedges will provide a better reduction in noise and evergreen ones will ensure the effect is year round. An alternative type of hedge for noise reduction is an ‘environmental barrier’ or ‘willow-walls’ whereby a screen of Salix viminalis (known as ‘osier) is created by weaving stems horizontally through vertical stakes. A second screen is created in parallel, then soil is packed between the two screens. The osier then roots into the soil core. The structure just needs occasional trimming of the top and sides back to the original structure.
Hedges can be beautiful items in themselves whether a flowering hedge is used (such as Rosa rugosa) or if the hedge is cut into interesting shapes (topiary). Less decorative hedges in a dark green (eg Taxus baccata) can also provide an excellent backdrop to a colourful flower bed.
A mixed, informal hedge can be a great advantage for wildlife in your garden. Many hedging plants benefit wildlife, be that by providing habitats, protection or food sources.
When planting hedging you need to keep in mind the amount of space the plant will require as it grows. As a rough guide, each row of the hedge will require about 90cm depth. As well as the depth and width of the hedge, you should consider whether you have any height restrictions, such as overhead cables, and select lower growing plants as appropriate.
Speed of growth
There is a marked difference between the speed of growth of different hedging plants and, therefore, how quickly the hedge will grow and how often they will need to be clipped. Quite often a gardener has a dilemma between wanting a hedge which will quickly grow to the required height and not wanting to prune it more than once a year. Unfortunately the only solution is to purchase bigger plants to start with!
The porosity of the hedge, ie the amount of wind which travels through it, will influence the protective qualities of the hedge. The denser the hedge the more shelter it will provide. You should also remember that deciduous hedges will provide significantly less protection in the winter.
Competition for water and nutrients
Hedges are hungry and thirsty plants, particularly those which are fast growing. They will generally out-compete any plants growing to close to them – you generally see that grass around hedges is patchy or dies altogether as water and nutrients are drawn away from it by the hedge. You should also ensure that a new hedge is well watered and fed in the first two or three years to help it establish.
All hedges, but particularly tall ones, will create a significant amount of shade. Before planting the hedge you should consider the direction it’s facing and, therefore, to what extent it will block sunlight reaching either side of the hedge (taking into account the ultimate height of the hedge). Creating shaded areas can be to the detriment of some plants (although others may be happy in shade) and to users of your, and neighbouring, gardens.
Formal vs informal
The style of your garden should also influence your choice of hedge. If you have a very formal design, then a hedging plant which is dense and slow growing will enable you to keep it well clipped and tidy. For more informal gardens, you can consider more ‘untidy’ and natural looking hedging.
Below are some suggestions of plants to use for hedging, with an indication of whether they are useful in formal and/or informal situations.
Deciduous hedging plants
- Berberis thunbergii - formal or informal flowering hedge, good for wildlife*, low growing
- Carpinus betulus (hornbeam) – formal hedge
- Corylus avellana – informal flowering (catkins) hedge, good for wildlife*
- Crataegus monogyna (hawthorn) – formal or informal flowering hedge, good for wildlife*
- Fagus sylvatica – formal or informal hedge, good for wildlife*
- Forsythia x intermedia ‘Spectabilis’ – informal flowering hedge
- Fuchsia magellanica – informal flowering hedge, good for wildlife*
- Potentilla fruticosa – informal flowering hedge
- Prunus spinosa cultivars – informal flowering hedge
- Rosa ‘Roseraie de l’Haÿ’ – informal flowering hedge, good for wildlife*
- Rosa rugosa – informal flowering hedge, good for wildlife
Evergreen hedging plants
- Berberis darwinii – informal flowering hedge, good for wildlife*
- Buxus sempervirens (box) – formal hedge, low growing
- Chamaecyparis lawsoniana (Lawson cypress), and most cultivars – formal hedge
- Cotoneaster lacteus – informal flowering hedge, good for wildlife*
- x Cupressocyparis leylandii (Leyland cypress) – formal hedge
- Garrya elliptica – informal flowering (catkins) hedge
- Ilex aquifolium (holly), and most cultivars – formal or informal hedge, good for wildlife* and security purposes (spiky leaves)
- Lavandula (lavender) – formal or informal flowering and fragrant hedge, good for wildlife, low growing
- Ligustrum (privet) – formal hedge
- Lonicera nitida – formal hedge
- Pyracantha - informal flowering hedge, good for wildlife* and security purposes (thorny)
- Taxus baccata – formal hedge
- Thuja plicata ‘Fastigiata’ – formal hedge
* If the hedge is clipped after flowering then some of the wildlife value will be lost as it will not fruit.
First of all you need to decide how many rows deep you want your hedge to be, which will depend on how dense you want your hedge to be. Hedging is generally one or two rows deep, although three rows are used where a particularly dense hedge is required (eg to enclose livestock).
The spacing will depend on the size of the plants, but the measurements can be used as a guide for most hedging plants:
Single row hedge:
Double/triple row hedge:
Note that where multiple rows are used then the plants should be staggered as shown above.
If you are planting a low growing hedge or parterre/knot garden (eg with box) then the plants should be spaced 10-15cm apart.
Hedges can be planted at any time of year. The best time is to plant then from autumn to spring, when there is unlikely to be a shortage of water. It can be cheaper to plant in winter as some hedging plants (many of the deciduous ones and also box) are available bare rooted, which is a more economical way of buying them.
The soil should be well prepared for planting a hedge – keeping in mind that this is a long term planting. Prepare the soil in advance, so you’re ready to plant the hedging as soon as you have it. Select a site which is appropriate for the plant/s selected and clear it of all weeds, debris and large stones. Double dig the soil, incorporating a good amount of organic matter, or work the organic matter well into the top 30-45cm of soil.
When you come to planting, use a line of twine strung tautly between two stakes to mark out the line of the hedge, to ensure you don’t accidentally end up with a wavy hedge! If you do want a curve in your hedge, then mark this out with sand or a hosepipe. Dig a trench or individual holes to the appropriate width (twice the width of the current container/root system) and depth (so the plant will be planted to the same height as it was originally) and loosen the soil around the sides of the hole/trench if you have clay soil. You can add mycorrhizae fungi into the planting hole, ensuring that it will be in direct contact with the plant’s roots, to help the hedge establish quickly.
Place the plant in the hole (spreading out the roots of bare rooted plants) and back fill gradually, firming lightly at each stage to ensure the roots have good contact with the soil. If you’re planting a bare rooted plant, jiggle it around a bit as you’re back-filling, to ensure the soil goes between the roots. Firm the top of the soil with your feet. Water well, top dress with a slow release fertiliser and mulch the soil along the full line of the hedge (without it touching the stems of the plants). Renew the fertiliser top dressing and mulch each spring.