What is cernage?

What is cernage?

When you want to move a large or medium specimen, it is important to take care in the preparation. This operation is called “ringing,” which involves digging an appropriate trench around the tree, cutting the roots and rootlets, in order to plan its relocation. The root system of a tree or bush is a crucial element, as their survival depends on it. The nutrients that nourish the tree pass through the roots and rootlets, so they must be healthy to keep the specimen in good condition. It may take several months or even years for the root system to strengthen and produce more roots and rootlets near the trunk to enable its relocation under the best possible conditions.

This relocation can occur when purchasing a large specimen from a nursery or from a professional; when a tree becomes too large or obstructs a construction; in this case, moving it becomes necessary. Ringing and transplantation prevent the need for felling the specimen.

When to intervene for girdling?

It is necessary to wait several months, up to a year, depending on the size of the subject, between girdling and transplanting, allowing time for the roots and rootlets that have been severed to regenerate and rebuild their nutrient reserves. The best time of year to girdle a tree is from early November to the end of February, outside of frost periods, during the dormant season.

It is important to know that trees with running or shallow roots, such as poplar, beech, willow, or ash, are more suitable than trees with deep taproots, such as oak, elm, walnut, or ginkgo for girdling.
Once girdling has been carried out, transplanting will take place from November to March for deciduous leafy trees; in September or March for conifers or evergreen trees. It should be avoided during the bud burst period of trees, from late winter to early spring, when the buds swell and then allow flowers and leaves to peek out, developing a fine down called ‘the fluff’.

How to practice ring barking?

When a tree has been in place for many years, its roots have developed well underground, and care must be taken not to damage them during relocation. How should you proceed with this girdling step?

For a small specimen, a tree with a circumference of less than 50 cm, either a spade or a trowel may suffice.
For a large specimen, greater than 50 cm in circumference, appropriate equipment such as a tractor and a professional will be necessary.

Here are the main steps:

• Water the surface soil thoroughly to facilitate the work.
• Mark around the trunk with chalk to outline the size of the root ball.
• Measure a diameter of about 10 times that of the trunk, taken 1 m above the ground.
• Dig a circular trench around the tree, directly beneath the branches, to a depth of about 50 cm to 1 metre.
• Using a pruning shear, a saw, or an axe, trim (cut) the roots and rootlets that resist.
• Wrap a biodegradable jute mat and then a fine mesh around the root ball to secure it and facilitate future relocation.
• Fill the trench with a mixture of sand and potting soil to create a light substrate.
• Create a basin for regular watering.

Once the tree is prepared, leave it for about 1 year before replanting to allow its root system to strengthen.

Tree in jute mat ready for transplantation

Crowning, on which plants should it be practised?

The operation of girdling is much more delicate on old ornamental or fruit trees that are already well established. Fruit trees are affected by this operation when they develop many leaves but few fruits. Girdling and transplantation help to strengthen the root system and ensure a good harvest of fruits. Both evergreen and deciduous trees, palms, and conifers can all be girdled.