Pleached or raised hedges are certainly in vogue in the garden world at the moment. Not that I am a stickler for fashion, but they really do have a great benefit to may landscape designs.
The name pleached is from the french word Pleacher, to braid or plait the branches of a tree. The technique of controlling and raising hedges, has been around for centuries, originally designed to created shaded walks for the gentry, and later moving into the kitchen gardens, for fruiting trees. A great way to keep the fruit accessible and maintained, also called Espaliered Trees.
So history aside how do these raised hedges relate to landscape design now? Well they have great qualities of added privacy, simple modern lines and form, and the use of using flowering trees, adds a great look and scent to a garden. They are best suited to the smaller blocks, that are often in need of privacy, but also that will ensure that they aren't too high maintenance. (you really don't want to be trimming miles of them).
The choice of trees to use in Queensland is fabulous, with different leaf forms, colours and textures, and growth rates, (often privacy is needed quickly for some clients). Interest can be added by mixing tree species, and heights along a length of a hedge. Even raising sections, in front of neighbours windows, and under planting with a contrasting shade tolerant ground cover. Establishment and maintenance is actually quite easy, and no harder than a hedge at ground level, you simply keep the lower branches clear. The choice of tree species will effect how many times a year the trees will need to be clipped. Olive for example you will cut once a year and leave in a more open branch style, whilst a Magnolia Teddy Bear, or Syzigium Australe Pinnacle (Lillypilly) will need a clip at least three times a year.
Trees to chose: Olive (light leaf colour open form, fruiting), Magnolia (deep green, good for shade, white flowers and scent), Lillypilly (Evergreen, inexpensive, flowering very easy to establish), Bamboo (go for Gracilis, easy to establish, modern look, very quick to get to full height), Camellias, Murraya, Fig also pleach very well.