Culture
Easily grown in humusy, moist to wet, well-drained soils in full sun to part shade. Plants prefer some part afternoon shade in hot summer climates. This is an aggressive perennial of wetland areas which can spread invasively by creeping rhizomes and self-seeding to form large colonies which displace native vegetation and disrupt habitat needed by certain types of waterfowl and fish. Eradication of the underground rhizomatous network present in established plant colonies can be difficult.
Noteworthy Characteristics
Lysimachia vulgaris, commonly known as yellow loosestrife or garden loosestrife, is a rhizomatous perennial that grows to 3-4’ (less frequently to 6’) tall on stiff upright stems clad with pubescent, ovate to lance-shaped, opposite or in whorls of 3-5, medium green leaves (to 4 1/2” long and 1” wide) which are dotted with black to orange oil glands. It is native primarily to wetland areas of Europe and Western Asia. It was introduced into North America in the early 1900s as a garden ornamental, but has since that time escaped gardens and naturalized in a number of damp habitats including marshlands, fens, wet woods, pond/lake margins, stream banks, waste places, ditches and along roadsides in Canada (Quebec, Ontario and British Columbia) and northern parts of the U.S. (Maine to Minnesota south to Illinois, Kentucky and Maryland plus Colorado, Montana, Washington and Oregon).
Cup-shaped, five-petaled, primrose-like, bright yellow flowers (to 1” across) bloom primarily in terminal panicles from June to September on soft hairy stems. Each flower has 5 yellow petals with reddish brown near the petal bases. Flowers are followed by 1/4” wide seed capsules which split open when ripe.
In the State of Washington, L. vulgaris is listed as a Class B noxious weed and is also listed on the Washington quarantine list meaning it is unlawful to transport, buy, sell, offer to sell, or to distribute this plant into or within the State of Washington.
Genus name honors King Lysimachus (661-281 B.C.), Macedonian King of Thrace and is derived from lysimacheios which was the ancient Greek name of a plant in this grouping.
Specific epithet comes from Latin meaning common.
Even though its common name is yellow loosestrife, Lysimachia vulgaris is a member of the primrose family and is unrelated to Lythrum silicaria, aka the infamously invasive purple loosestrife, which is a member of the loosestrife family.
Problems
No serious insect or disease problems. Lysimachia is susceptible to rust and leaf spots. Plants should be closely monitored to avoid unwanted spread in the landscape.
Uses
Notwithstanding its long and showy bloom of bright yellow flowers, this plant should not be grown in areas where it is expected to spread invasively. It is best located in moist areas separated from other valued perennials where it can be allowed to naturalize into colonies. May be grown in cottage gardens, wild gardens, remote parts of borders, bogs, pond peripheries or along streams.