Hedges can be crisp and formal with sharp edges and geometric lines or more informal affairs needing little or no pruning. To add interest consider planting a stepped hedge where several rows of plants of differing heights are used stepping up from a small hedge at the front to a tall hedge at the back. An informal hedge of a strappy-leafed plant such as liriope, or agapanthus could be used at the front with clipped formal hedges behind of box, gardenia, murraya or lilly pilly.
Benefits of a formal hedge
Formal hedges add a smart geometric design element to a garden but must be regularly maintained with clipping or pruning to keep them looking good. Depending on growth rates, formal hedges may need an annual prune or they may need clipping every six to eight weeks in the growing season. Regular pruning produces flushes of new growth. Coloured new growth such as seen on a photinia hedge can add to the appeal of a clipped hedge.
Formal hedges can be used along a boundary, to edge a path or driveway or to create internal divisions within a garden. One stylish use is to add structure to an informal garden by using formal hedges to contain loose plantings of perennials or grasses. Also consider crisp box hedges around a rose or vegetable garden or a dark green conifer hedge to block a busy road.
Benefits of an informal hedge
Informal hedges soften a garden or a view even though they may be containing or dividing a space, blocking an unwanted view or providing privacy. They need infrequent pruning especially once established and can be allowed to bloom and even produce fruit. Although they need little pruning some pruning may be needed after flowering or to restrict height or spread.
They suit an informal garden or an area that receives little maintenance such as a garden at a holiday or rental home, a farm windbreak or wildlife corridor, or in an area that’s hard to access.
Without regular pruning to keep an informal hedge in check it is important to select a plant that will grow to the height and width that the space allows.
Choosing a hedge plant
Features to consider when choosing a plant for any sort of hedge include its colour (for example does it have colourful foliage, seasonal colour from new growth, or does it produce seasonal flowers), its growth rate, ease of pruning and its size (both height and width).
As well, plants need to be long-lived, resistant to pests and diseases and compatible with the climate, soil and aspect where the hedge is to grow.
One of the most important features however is uniformity of growth so each plant in the hedge has the same growth rate. This creates an attractive hedge and simplifies maintenance. Named cultivars are clones from a single plant so generally have uniform characteristic and produce a more homogeneous hedge than one from seed-grown plants.
Hedge suggestions and planting guides
Some plants can be used as formal or informal hedges depending on frequency of clipping. For uniformity select named, cutting-grown cultivars. Hedge plants are generally spaced between 30cm and 100cm apart depending on the plant’s size and vigour. Closer spacing gives a faster hedge but can lead to root competition and overcrowding as the hedge matures.
As a guide, space plants at half their mature width apart. Use a string line to make sure plants are in a straight line and use a measuring tape so the space between each plant is the same.
Plants suited to formal hedges
Abelia, azalea, bougainvillea, box, camellia, conifer (eg cypress), coprosma, duranta, gardenia, lavender, lilly pilly, murraya, photinia, pittosporum, plumbago, rosemary, viburnum, westringia.
Plants suited to informal hedges
Abelia, agapanthus, alternanthera (eg Little Ruby), azalea, bamboo, bottlebrush (Callistemon), camellia, flax, feijoa, grevillea, hebe, hibiscus, lavender, lilly pilly, nandina, oleander, plumbago, rose (eg Rosa rugosa), viburnum, westringia.