Restoring Established Ornamental Gardens

Replacing an Old Hedge

Sometimes the plants in a hedge are beyond restoration – the hedge may have been damaged by fire or disease. When restoring an old garden you may need to replace the existing hedge or put in a new hedge where an old one grew in the past.

Hedges and neighbourhood Disputes

Hedges can cause disputes with neighbours. When re-planting a hedge:

·         Make sure that when fully grown (in width) it will be well within the garden and doesn’t encroach on neighbouring properties. Remember that any encroaching plant material including roots may be removed by the neighbours.

·         Choose plants that are easier to keep to a certain height so as to not over-shadow and exclude light to neighbouring properties or gardens in the future.

·         Make sure that a new hedge will not deprive neighbours of an important view.

·         Some hedges may need planning permission for removal.

Plant Choice

Some plants such as some conifers, will not tolerate constant cutting; and others simply do not develop dense, even growth. The best hedging plants usually have small leaves; though for larger hedges, larger leaved plants may be acceptable. A large hedge will require a lot of plants - which is expensive; difficult-to-grow plants may be less desirable economically. However when replacing an old hedge in a garden restoration project it is best to choose the plants that were used originally, if at all possible or practical.

In choosing the plants, consider the following:

• Is the hedge to be evergreen or deciduous? Deciduous and many evergreen hedging plants can be pruned more regularly and vigorously then some conifers which die back if you cut into old wood.
• Informal or formal? Formal hedges need to be clipped frequently so choose a species that will tolerate frequent cutting.
• Height - consider the plant’s natural size at maturity – for a 1 m high hedge, don’t choose plants which naturally grow to 3 or 4 m. 
• Density - a more open hedge will give better air circulation but less privacy.
• What size plants are to be used? Advanced plants can be very expensive but will give an almost instant effect; smaller plants are cheaper and often give better results in the long run.
• Quick effect - many fast-growing plants will rapidly develop into a dense hedge but will require frequent clipping to maintain a tidy shape. Some may also be short-lived.
• For a uniform hedge - buy sturdy plants of around the same size. Branching is important so it’s best to select plants dense, bushy plants to get the hedge off to a good start.
• Slow growing plants are often longer lived then fast growers.
• Pruning - hedges such as Taxus and Juniperus have narrow leaves and make excellent hedges that rarely need more than one pruning; usually in early spring a follow up pruning in autumn is sometimes required in temperate areas. Spruce and pine should not be cut further then the current year’s growth – prune back only part of the current growth each year.  Viburnum and buckthorn are easily shaped into an arch.

Preparing the Site

The secret to a successful hedge is correct soil preparation. Once you have decided where the replacement hedge is to grow set up a stringline to mark the planting positions. Dig a trench along the entire length, and add well rotted organic matter to the soil. Leave for a month or so to allow the soil to settle before planting.

Establishment

To establish a straight hedge, set up a stringline and dig a trench along the length of the proposed hedge. Improve the soil with organic matter and fertiliser. Plant the shrubs/trees at the desired intervals, then water and mulch.

Depending on the size (and species) of the new plants, training should be started immediately:

• Cut back about 1/3 of the growth to encourage dense, new growth.
• Trim the plants lightly to maintain shape and density but wait until the second year before giving another hard prune (ie. removing 1/3 off the height).
• Once the hedge has reached the desired height, trim it two or three times each season. This is especially important for conifers, which need regular light trimming rather than hard cutting.

Spacing Plants

Work out how many plants are needed – the spacings will be much closer than is normally recommended for plants grown in the open; for example, small-leaved box and lavender are spaced about 30 cm apart and Leyland cypress about 75 cm apart.

Hedge Trimming

• Put pegs in at either end, stretch a string line at the desired height then trim to the line to ensure a straight edge.
• Line up the edge with an object at the end of the hedge
• Mark a line on the ground at the hedge base with lime.
• Cut a little bit at a time, stand back, evaluate, and only then cut more. (You can always take more off, but you can’t put it back after removing it!)

The base of the hedge should be clipped slightly broader than the top, with an even taper from the bottom to the top. This allows better light penetration to the lower parts of the hedge, resulting in more even foliage growth.