With a taut, upright, slender silhouette, the columnar oak stretches up to 20 m into the sky. The Quercus robur retains its elegant stature without any horticultural intervention, so that pruning is not absolutely necessary. In order to regulate their height and width, there is nothing against a topiary. Here we explain what you should pay attention to.
Oak trees are best pruned in the fall
The recommended time is late winter
A pruning in the middle of the season means pure stress for your columnar oak and is forbidden for reasons of bird and nature protection according to the Federal Nature Conservation Act, paragraph 39. Therefore, choose a date in the middle of the sap dormancy between the beginning of October and the end of February. This has the advantage that the tree does not wear its foliage, so you have a clear view of the arrangement of the branches. This allows a precise cut, which benefits the harmonious look. In practice, a frost-free day between January and March has proven to be excellent, just in time before fresh shoots appear.
How to guide the pruning shears correctly
A conscientious pruning is rewarded on a columnar oak with a dense foliage and compact growth. It is important where you put the scissors. A cut a few millimeters above a sleeping eye acts as an impulse for a shoot. Therefore, look out for small bumps under the bark to cut the branch at this point. Also pay attention to these aspects:
- Don't just cut the crown of a columnar oak, but shorten it all around
- Remove steeply ascending and inward branches
- Clear out all dead wood
As the work progresses, repeatedly step back a few steps to plan the next cuts. The natural growth form should be preserved as far as possible, even after a more extensive topiary. The cuts should be smooth, clean and on knots. Fraying must be avoided at all costs.
Avoid cutting into old wood
Regardless of its tolerance for pruning, a columnar oak has a hard time sprouting out of old wood. Therefore limit the extent of the pruning to the growth of the last year, at most the last 2 years. If there is limited space available from the outset, we therefore recommend an annual topiary of a maximum of one third.
tips
The mother of all German columnar oaks can still be visited today. Visit the 'Beauty of Harrenhausen' in Babenhausen in Hesse. The magnificent tree has been thriving here in the Harrenhausen district for more than 570 years. Its seeds are considered a rarity among enthusiasts and boast a high success rate of columnar offspring.