Mentioning loosestrife in garden-savvy company can bring glares and scowls.
Most associate this common name with purple loosestrife, the invasive plant with showy purple flower spikes that often grows in wet ditches and along the water’s edge.
This bad boy is lythrum, a European native brought here for use as an ornamental garden plant, but which eventually escaped into natural areas where it displaces wetland plants like cattails and rushes. It has now been banned from sale in many states, including Michigan.
Ironically, the term loosestrife is derived from the word Lusimakhos, the name of the person credited with discovering another plant, Lysimachia. Lusimakhos also translates in Greek to loose-strife, which became the common name for Lysimachia as well as Lythrum. The genus Lysimachia includes a number of excellent garden plants and should not be painted with the same brush.
I am particularly sensitive to the comparison since one of my favorites is a purple-leaf species; Lysimachia ciliata Purpurea, or purple-leaf loosestrife. New growth emerges in spring nearly black and expands to dark mahogany leaves with a coppery undertone. In summer, stems are topped with open sprays of bright yellow, five-petaled flowers that harmonize beautifully with the foliage. In a fertile, consistently moist soil it can be a vigorous spreader. I’ve grown Purpurea in heavy clay and in light, sandy soil, and both seemed to keep the plants in bounds, as it’s been well-behaved for me. Plants grow in full sun to half shade and reach 24 to 36 inches tall.
Circle flower or yellow loosestrife, Lysimachia punctata, has bright green foliage and spires of tiered, vibrant yellow flowers in late spring to early summer. Like purple-leaf loosestrife, plants are good neighbors if they are in drier soils or heavy clay, and make a dramatic large-scale ground cover in moist, rich soils where allowed to spread. Upright plants grow 18 to 36 inches tall, and are hardy to Zone 4. Alexander is a variegated form with a more subdued growth rate even in ideal conditions, and has leaves boldly splashed in white that carry the show after flowers fade. Golden Alexander has yellow variegation.
Gooseneck loosestrife, Lysimachia clethroides, has densely flowered clusters in slender, curving white spires three to six inches long that resemble, not surprisingly, the neck of a goose. The plant is quite vigorous in moist, fertile soil, where it will form sweeping masses and reach 36 inches tall. I have mine planted in full, bright sun and dry soil, where it reaches about half the height and makes a nice floral display in summer, but hasn’t spread.
Creeping Jenny, Lysimachia nummularia, is undoubtedly the most popular and versatile of the lot. The green-leaf form is a fantastic ground cover for moist to set sites, reaching only two to four inches tall and spreading quickly to form a dense, weed-free mat, in sun or shade. Goldilocks, Goldi or Aurea are forms with leaves so bright that it can be hard to notice the yellow spring flowers. Often sold with the annuals as a cascading foliage ‘spiller’ for mixed containers, just plant a bit in the ground in fall, and you’ll have plenty for nest spring.
Golden Globes, Lysimachia congestifora (aka procumbens) varieties are less winter-hardy, but well worth growing as annuals. Low, spreading plants grow six to eight inches tall and work well at gardens edge or cascading from containers. Flowers are the classic yellow, but with a red throat, and held in rounded clusters just above the foliage. Aurea has golden foliage, and Outback Sunset and Waikiki Sunset have green and gold variegation. Persian Chocolate brings dark bronze foliage and is a bit more petite overall.