Bushes and shrubs that flowered in spring should be early summer, preferably shortly after flowering,cut. How come? Can't you just let them grow?
Of course you can, but doing so runs the risk that the bushes will produce fewer flowers year after year and thus become more and more dense, but no longer show the blooming splendor that it could be.
Pruning bushes after flowering
That is why you should cut and thin out branches that are several years old after flowering. The branches are cut off about a third above the ground and young shoots are also shortened by a third. So don't do this in spring, otherwise you risk that the plant will not flower particularly profusely. However, if you prune in early summer, then it will have until next spring to produce plenty of new young shoots.
This pruning is particularly recommended for the following plants:
Lilac, forsythia, Deutzia, scented jasmine and Kolkwitzia, spirea