Description from White Flower Farm

L. clethroides is better known as Gooseneck Loosestrife because its slender arching spikes of white flowers have a graceful crook that makes them seem friendly and informal. Bloom is abundant from July into September; the plants in our propagation blocks produce a sea of white spikes every summer. Plants grow to 3ft and are vigorous to the point of invasiveness, which we prefer over plants that limp their way through the season. A superb ground cover in any soil, in full sun or partial shade; it also deserves a role in the border with plants that can help restrain its enthusiasm. Try it with Monarda or Heliopsis. Lysimachia makes a good cut flower and with Amsonia and Platycodon boasts some of the most striking fall color to be had in a perennial garden.