Many delightful garden plants have their origin as weeds. Purple Loosestrife (Lythrum salicaria) has this humble origin and is often visible from the highway growing in profusion in bogs and marshes. In fact, in some areas such as Minnesota, it threatens to choke wetlands and its sale is restricted. In response to considerable environmental concern, commercial production and sale of this perennial flower has recently been essentially limited to the varieties that are sterile and do not spread rampantly across the landscape. This is an advantage for the homeowner as well as the environment, because once tamed, these plants are real assets in residential yards. They display striking flowers from June to September on tall, graceful, sturdy stems. Perennial, they die back over the winter and sprout again in the spring. They are virtually carefree.
Size: Purple loosestrife plants typically grow to 3 or 4 feet tall. The top 6 to 12 inches of the multiply branched plant stems form the flower spikes. A dwarf version called `Happy' grows only 15 to 18 inches tall. Individual plants spread into clumps about 3 feet across after 3 to 5 years.
Foliage: Purple loosestrife leaves are about 4 inches long. Narrowly lance-shaped, they have smooth edges and sharply pointed tips. They grow opposite each other along plant stems, or in whorls, 3 to a group, around the stems. Typically the foliage is a dull medium green, sometimes darker. Leaf undersides are somewhat paler. The foliage of `Robert' variety show some color in the fall.
Flowers: The tiny individual purple loosestrife flowers measure only about 3/4 inch across. They are clustered along the top 6 to 12 inches of plant stems, interrupted occasionally by tiny leaflets. As the plant name suggests, the flowers are usually shades of purple or deep red or pink.
Choose nursery stock that is labeled as sterile and will not spread by self-seeding.
`Dropmore Purple' has purple flowers;
`Firecandle' has rosy-red flowers;
`Happy' is a dwarf form, dark pink;
`Morden's Gleam' has red flowers;
`Morden's Pink' is tall, has pink flowers;
`Purple Spires' is tall, fuschia colored flowers;
`Robert' has fall foliage color, purple-rose flowers;