How to Prune High Mallow
When is the best time to prune?
High Mallow blooms from late spring through late summer across its wide hardiness range of zones 4-8, with timing for the fall cut-back varying by 4-6 weeks across regions.
Why Should I Prune My High Mallow?
High Mallow is a vigorous bloomer that produces funnel-shaped flowers with distinctive dark veining from late spring through summer. Left without deadheading, it puts energy into setting seed and slows down flowering. More importantly, it self-seeds freely and can become invasive in some garden situations.
Regular deadheading, removing spent flowers before the seed pods develop, keeps the plant blooming longer and limits the spread. Snip or pinch off each spent flower at the base of the flower stem, just above the nearest set of leaves.
High Mallow has a somewhat sprawling, upright growth habit and can get tall and floppy by late summer. Cutting back by about a third when blooming slows helps tidy the plant and often encourages a late-season flush of flowers.
This plant is short-lived as a perennial and behaves like a biennial in cooler zones. Some gardeners let a few flowers go to seed each year to ensure the next generation, then remove the parent plants. If you want to control self-seeding, deadhead consistently and collect a few seed heads intentionally rather than letting them scatter.