In the first version, you plant a hedge of the required size and just cut it into shape every year. This hedge will have its densest branching at the points which have been cut back and therefore at which most branching occurs: directly at the outer frame of the hedge. If it is a deciduous hedge, for example a hornbeam hedge, it will be rather sparse overall when leafless.
A dense hedge, on the other hand, results if, instead of the planned final height, you only use plants which are a third or half as large. Then prune the hedge twice during the year: once at the end of May or beginning of June. Then at the end of June, the hedge will sprout a second time. Prune a second time in August/September. Then shorten the youngest twigs by 50 to 70 per cent of their length. With this cutting method you obtain new shoots twice a year, in order to encourage growth of the hedge in height and width. However, as you force the plant each time to branch off at the point where it is cut back, with every cut you simultaneously build a branching level into the hedge – two per year. In this way, your hedge increases in height from year to year by approximately half a metre but, due to the much stronger branching, is much denser than the version planted with a final height.
The width of the hedge depends on its height: in order not to grow bare in the lower reaches, the hedge must be wider at the bottom and narrower at the top. Therefore, cut each side of the hedge ten centimetres narrower per metre. Example: the hedge is two metres high and its base 80 centimetres wide. On each side of the hedge, therefore, cut by 2 x 10 centimetres, i.e. 20 centimetres narrower. Therefore, narrowed on both sides together by 40 centimetres, the hedge is 80 centimetres wide at its base but only 40 centimetres at the top. To cut the hedge height and width more precisely, it is recommended at least while building up the hedge to create a string framework as a visual aid with the aid of a guide line (for example bricklayer’s plumbline from the DIY store). For this, fix the line at the appropriate height and width to support rods (iron poles, wooden poles) along the hedge so that the line does not sag.
Tip: A better appearance is achieved by cutting hedges of Thuja Columna by making a fine cut with garden shears. Instead of cutting the “heads” of the Thuja off with the hedge shears like a paintbrush, it is better to thin out the top part tapering to a point with the garden shears and then reshape.