With a tightly upright, slender silhouette, the columnar oak stretches up to 20 m high towards the sky. The Quercus robur maintains its elegant stature without any gardening intervention, so pruning is not absolutely necessary. In order to regulate their height and width, there is nothing wrong with a topiary. We explain here what you should pay attention to.
When is the best time to prune a columnar oak tree?
A columnar oak should be cut when the sap is dormant between the beginning of October and the end of February, ideally on a frost-free day between January and March. Limit pruning to last year's growth, make clean cuts on Astring and maintain the natural growth habit.
Recommended time is in late winter
Pruning in the middle of the season means pure stress for your columnar oak and is prohibited for bird and nature conservation reasons according to the Federal Nature Conservation Act, Paragraph 39. Therefore, choose a date during 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 for precise cutting, which benefits from the harmonious look. In practice, a frost-free day between January and March, well before the fresh shoots, has proven to be excellent.
How to use the pruning shears correctly
A conscientious cut on a columnar oak is rewarded with a dense foliage and compact growth. Where you place the scissors plays a crucial role. A cut a few millimeters above a sleeping eye acts as an impulse for sprouting. Therefore, look for small bumps under the bark to cut the branch at this point. Please also pay attention to these aspects:
- Don't just cut a columnar oak in the crown, but shorten it all around
- Remove steeply upward and inward-facing branches
- Clear out all dead wood
As you work, take a few steps back to plan the next cuts. The natural growth habit should be retained as much as possible, even after extensive topiary pruning. Cuts should be smooth, clean and on astring. It is essential to avoid fraying.
Avoid cutting into old wood
Regardless of its tolerance for pruning, a columnar oak has a hard time sprouting old wood. Therefore, limit the amount of pruning to the growth of the last year, at most the last 2 years. If there is limited space available from the outset, we recommend pruning by a maximum of a third every year.
Tip
The mother of all German columnar oaks can still be visited today. Visit the 'Beauty of Harrenhausen' in Babenhausen, 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 descendants.