The ideal time to prune lilacs extensively is spring or fall. During the summer months, only minor pruning is possible to maintain flowering and protect wildlife.
When caring for the lilac, annual pruning is crucial.
The aim of pruning
- stimulate growth and flowering
- achieve dense branching
- keep in shape
- thinning out dead wood and disturbing shoots
- revitalize older specimens
To avoid frost damage to wound areas, prune lilacs only at a time outside the frost period. In addition, for deep pruning, it is recommended to do it in the fall or early spring.
Pruning measures to be carried out annually on the lilac tree or bush can be basically divided into:
- Maintenance pruning
- Rejuvenation pruning
Depending on the age of the plant, the intensity of the necessary work and when to perform it varies.
Regardless of the intervention, it is very important to use the right pruning tools. In principle, the use of standard pruning shears is sufficient.
Maintenance pruning is the most common form of pruning and should be preferred to radical pruning whenever possible. After the young plant has been trained to the desired growth habit in its first few years of standing, maintenance pruning is used to maintain the shape.
The earliest possible time to prune lilacs for this purpose is late summer or autumn, and the flowering period should be completely over before starting work. The measures here extend to:
cut flowers as far down as possible
cut biennial branches to a maximum length of three branches
shorten one-year-old shoots if necessary
Rejuvenation pruning, which is the most radical of the three pruning methods, should be used only in exceptional cases. Excessive pruning results in high stress on the plant, which is accompanied by a cessation of flowering. Nevertheless, rejuvenation pruning can be useful if it is unavoidable to shorten the plant significantly due to disease or weather conditions.
However, the individual branches should not be cut back too far into the wood. To allow for new growth, at least three branches should be left behind. Such radical pruning should therefore only be carried out in spring. This allows the newly sprouted branches to reach winter hardiness until the next frost period.
Frequently asked questions
What to do in case of missing education cuts on a young plant?
Failure to make education cuts will result in immense height and width growth in the first few years of standing. This, however, is accompanied by subsequent internal thinning and reduced flower formation. The lilac should therefore be brought into shape as quickly as possible by means of a maintenance pruning. Under no circumstances should radical pruning be relied upon, as this further weakens the plant.
What are the consequences of radical pruning of the plant in autumn?
Lilac belongs to those plants that form their flowers exclusively on biennial wood. For this purpose, the corresponding shoots are already created in the autumn of the previous year. Pruning them in the fall makes it impossible for the plant to form new shoots, so the flowering stops.