Agdex No. 276.21
Hedges are a unique and useful part of landscapes. Hedges can keep people or animals in or out, mark boundaries, act as windbreaks, and provide privacy for a garden. They may also act as a background for colourful garden displays or add colour to a winter landscape. Because a hedge's purpose is to form a barrier, it should always end at a fixed object so as not to appear to be lost in space. The size, shape and texture of a hedge is determined by the architecture of the buildings nearby, the effect to be created as well as the purpose of the hedge.
Many factors must be considered when selecting a hedge plant. Evergreen hedges are green all year and provide colour and contrast in the winter. Deciduous hedges can provide a great variety of leaf colour and texture, interesting berries and beautiful displays of blooms in season.
There are several advantages to using quality nursery grown hedge stock as opposed to wild stock. Nursery grown plants are well shaped, dense, relatively free from pests and diseases and have a better developed root system than wild stock. Wild plant stock can develop into an attractive hedge, but it may take a longer time.
The height of a hedge depends on its purpose. A privacy hedge should be 150-200 cm high. Hedges around large gardens should be taller than those around small lots so the hedge is in proportion to the landscape. Tall hedges can have coarser textured leaves and twigs which make an area appear smaller. Fine textured, dull foliage hedges make an area look larger and are more appropriate for small gardens.
Hedges of bright green, golden or grayish foliage make a stronger impression than hedges of dark or mid green. Large hedges, may be overpowering in a bright colour whereas low hedges can use brighter shades for emphasis. Flowering hedges add variety by giving a burst of colour when in bloom. Berries also add colour to a landscape, often in the duller months of the year.
For information on planting refer to New Brunswick Department of Agriculture Publication, 'Planting Trees and Shrubs'
The ideal hedge plant is one that branches from the ground to the top of the plant, as this type of plant will develop a very dense growth habit. Therefore, small plants are usually chosen for starting hedges as these plants can be more easily trained into the desired shape and density. Two year old deciduous plants with extensive branching make good hedge plants. Tall spindly deciduous plants should not be used unless they are cut back to about 15 cm from the ground. For evergreen hedges 4 year old plants, with dense growth are best. Avoid plants with very thin growth or few branches at the base because conifers are unable to develop new growth from old wood and bare spots may never fill in properly.
A single row hedge planting is the preferred planting method. There is less competition between plants and they are easier to trim and care for in the future.
Plant spacing for hedges vary with plant species and the desired mature height of the hedge. 46 cm between plants is correct for most hedges. Low hedges or hedges with plants that have a very erect growth habit can be planted closer together. For tall hedges, particularly evergreen screens or windbreaks, plants should be spaced 60 to 90 cm apart.
When planting, plan for the mature width of the hedge. A 1 m barrier hedge should be expected to have a mature width of 1 m. If a hedge is to be the property boundary, it should be planted .75-1 m from the property line to allow for the hedge to spread and still be maintained on one property.
SHEARING AND PRUNING
Hedges are sheared to promote new thick growth and to provide a smooth dense foliage surface. Trim the top and sides of a hedge at least once a year until it reaches its mature height. Fast growing hedges may require trimming 2 to 3 times a season to keep their shape. Do not allow a hedge to grow rapidly to its desired height before trimming or it will develop a thick top and open sides.
Most evergreen hedges are best sheared before the spring growth period is complete in about mid-July. The exceptions are Cedar and Yew hedges which can be sheared any time during the growing season. Deciduous hedges that do not flower or flower late in the summer are best pruned during the dormant period in the spring while spring flowering hedges should be pruned after bloom period. Flowering hedges are rarely sheared as shearing changes their natural shape and reduces their floral display.
Once a hedge has attained its mature height, trim back close to the base of the current season's growth so it is allowed to grow only 3-5 cm in height and width each year.
Hedges that are shaped with a rounded or pointed top are less likely to be broken down by the weight of ice and snow. Hedges should also be wider at the base than at the top so foliage on the sides of the hedge receives sufficient light to manufacture food; otherwise a poor hedge results.
It is possible to renovate old deciduous hedges by cutting them back in early spring. Using secateurs, remove dead wood and cut thick branches to 10 cm below desired height. Young wood on sides should then be trimmed to 15-25 cm below desired height.
Evergreen hedges recover slowly from a severe cutting back and usually it is better to remove an old hedge completely and plant again.
If a hedge is growing well, if does not need fertilizer. Fertilizer may be necessary to aid in hedge establishment and every 2 or 3 years to maintain plant vigour.
Fertilize with an organic mulch of compost, rotted manure, or straw, then add a general purpose fertilizer (6-12-12 etc.) to supply N for decomposition. For a hedge 20 m long, 1m3 of mulch and 2 kg of fertilizer are sufficient.