Topiary is the practice of training trees and shrubs to defined shapes.
Generally evergreen subjects with small leaves or needles are the easist forms to produce and maintain these defined shapes.
Typical subjects are: Bay trees (Laurus nobilis),Common Box (Buxus sempervirens) Privet (Ligustrum) and Yew (Taxus)
Initially the gardener may use shaped wire cages to guide him/her until such times as the subject is of the desired shape and size.
After this light trimming is generally all that is required to keep the tree in check.
Start shaping plants in early summer, the easiest shapes to create are cones, globes, pyramids and obelisks.
There are various tools one can use for trimming the initial shaping e.g. hedging shears, topiary shears or secateurs.
Be careful at all stages of trimming, not to cut too much off.
Allow conifers to reach the full height of the envisaged shape before cutting.
Globes: trim around the centre first, before shaping the top and bottom.
Cones, obelisks or pyramids: cut a vertical strip from the four corners to the tip before clipping in between, this should prevent one-sidedness.
A sloping cane fixed to the desired angle as a guide can also help when starting off these shapes.
Alternatively, place wire former/s over the plant and clip it to shape once the plant has grown through.
Using wire is of great help when creating more complex shapes such as spirals, arches and animals.
Once the shape is established an annual trim in early and late summer should keep most topiary in shape.