How to prune marshmallow

Spring for pinching; late summer after bloom; late autumn for full cutback. Pinch or snip stem tips to 15–20 cm in spring to promote bushy growth. After blooms fade, cut flowered stems back by half. In autumn, cut all stems to 10–15 cm above the base.

Twice to three times per growing season; hard cutback annually. Marshmallow is a tall, vigorous perennial that benefits from cutting back. Pinch growing tips in spring to encourage branching and a sturdier plant less prone to flopping. After flowering, cut stems back by half to tidy the plant. In late autumn, cut the whole plant to near ground level as the top growth dies back.

Pinch or snip stem tips to 15–20 cm in spring to promote bushy growth. After blooms fade, cut flowered stems back by half. In autumn, cut all stems to 10–15 cm above the base.