How to prune symphyotrichum novae-angliae 'andenken an alma pötschke'

Late spring (Chelsea chop); late autumn after flowering for cutback. In late May to early June, cut all stems back by one-third to one-half using shears. After flowering finishes in autumn, cut the clump to ground level.

Annually (Chelsea chop + post-flowering cutback). This New England aster benefits from the 'Chelsea chop' — cutting stems back by a third to a half in late spring. This delays flowering slightly and produces a more compact, bushy plant with more blooms. Cut the whole plant to ground level in late autumn or early spring after flowering.

In late May to early June, cut all stems back by one-third to one-half using shears. After flowering finishes in autumn, cut the clump to ground level.