How to prune new england aster

Late spring to early summer for pinching; after first hard frost for cutting back. Pinch or shear stems by one-third to one-half before mid-July to prevent flopping and promote branching. In autumn after frost, cut all stems down to 2–3 inches above the crown.

Annually — pinch once in early summer, cut back once in late autumn. New England Aster benefits from pruning to control its tall, floppy habit and extend bloom. Pinch or cut stems back by one-third to one-half in late spring to early summer to encourage bushier growth and more flower heads. Remove spent blooms to tidy up, then cut stems to the ground after frost kills the foliage.

Pinch or shear stems by one-third to one-half before mid-July to prevent flopping and promote branching. In autumn after frost, cut all stems down to 2–3 inches above the crown.