ECHPC – Purple Loosestrife

ECHPC – Invasive Plant Initiative for Purple Loosestrife

USDA-NRCS Invasive Plant Identification Sheet – Purple Loosestrife (Lythrum salicaria)

Purple LoosestrifeThe purple loosestrife (Lythrum salicaria) is perhaps the most commonly known invasive plant, and is the reason for many states having laws and regulations on such plants.  It was introduced from Europe in the early 1800’s, and is the spiked flower about three feet high seen blooming in wet areas (such as marshes and roadside ditches) in mid to late summer.  This genus should not be confused with another loosestrife (Lysimachia) which spread aggressively by roots.

Alternatives to the purple loosestrife, also with purple flowers, include many cultivars of bee balm, coneflower (Echinacea), and swamp milkweed.  These get about the same height and give a similar effect planted in mass. Taller is the Joe-pye weed, which prefers moist to wet soil, as does the swamp milkweed.  The bee balm need moist soils.  The coneflower grows in moist or dry soils, but just needs well-drained soil.


  • UCONN Connecticut Invasive Plant Working Group – Purple Loosestrife – is a wetland perennial native to Eurasia that forms large, monotypic stands throughout the temperate regions of the U.S. and Canada. It has a vigorous rootstock that serves as a storage organ, providing resources for growth in spring and regrowth if the plant has been damaged from cuttings. New stems emerge from the perennial roots enabling the plant to establish dense stands within a few years. Seedling densities can approach 10,000-20,000 plants/m2 with growth rates exceeding 1 cm/day. A single, mature plant can produce more than 2.5 million seeds annually which can remain viable after 20 months of submergence in water. In addition, plant fragments produced by animals and mechanical clipping can contribute to the spread of purple loosestrife through rivers and lakes.
  • UCONN Integrated Pest Management (IPM) for Purple Loosestrife – Integrated Pest Management (IPM) methods can be used to control invasive plants in backyards, in parks, and in natural landscapes. IPM technologies include the use of biological, mechanical, cultural, and chemical controls. Biological control, the use of natural enemies to reduce an invasive plant’s population below a biological or economic threshold, is a sustainable, low-input method to control a widespread invasive plant, purple loosestrife (Lythrum salicaria).  This project is no longer funded. For general information on invasive plants, please contact the Connecticut Invasive Plant Working Group (CIPWG):

Concrete is heavy; iron is hard – but the grass will prevail.

Edward Abbey