Common Reed (Phragmites australis )
Caution!! Since common reed is a grass, cutting several times during a season at the wrong times may increase stand density.
- Hand-cut individual stems at the end of July when most of the plant’s food reserves are in the aerial portion of the plant, before the flowers produce seed. Plants should be cut below the lowest leaf, leaving a 6 inch or shorter stump. Hand-held cutters, gas-powered hedge trimmers and weed whackers with a circular blade are particularly efficient. You can also cut and mulch dead stems in winter to remove them and promote germination of other species. Repeat in second year and then every three to five years.
- Cut stems can be composted or allowed to decay in a dry area.
- Some patches may be too large to cut by hand, but repeated cutting of the perimeter of a stand can prevent vegetative expansion.
- Mow large stands of common reed annually between June and July to reduce plant vigor and stem density. Common reed will spread by seed or root pieces, so be sure to thoroughly clean all mowing equipment after its use to prevent the reed’s spread.
- After cutting, lay a sheet of black plastic over the area. Use sand bags or bricks to secure the edges and keep covered for a year. Check for new growth around the plastic.
For small infestations: Cut the plants back in the winter. In late summer, cut stems of common reed and drip an 18-21% glyphosate solution into the stem.
For larger infestations: Cut the plants back in the winter. In late July or early August, when the plants are flowering, use a car wash mitt to wipe a 2% glyphosate solution onto the entire plant. Repeat in following years as necessary.
"Common reed is a tall, perennial grass that can grow to heights of 15 ft. (4.6 m) or more. Broad, pointed leaves arise from thick, vertical stalks. Leaves are 6-23.6 in. (15-60 cm) long, 0.4-2.4 in. (1-6 cm) wide, flat and glabrous. The flower heads are dense, fluffy, gray or purple in color and 5.9-15.7 in. (15-40 cm) long. Flowering occurs from July to October. Common reed is usually found in dense thickets growing in or near shallow water. These thickets displace native wetlands plants, alter hydrology and block sunlight to the aquatic community." (source: www.invasive.org)
Reproduction is thought to take place mainly through vegetative means via rhizome and stolon fragments. Rhizomes spread horizontally during the growing season. New stalks shoot in spring, and flowers appear in late June with bushy panicles. Seeds form by August to early fall and are dispersed between November and January. Following seed set, nutrients are translocated down into the rhizomes and the above-ground portions of the plants die back for the season. Water depths of more than 5cm and salinities above 20ppt (2%) prevent germination. Percentage of germination increases with increasing temperature from 16 to 25˚C while the time required to germinate decreases from 25 to 10 days over the same temperature range.
Seeds are normally dispersed by wind, but may also be transported by birds that nest among the reeds.
Photos: (c) R. Old XID Services, Inc.; B. Blossey, Cornell University; (c) L. Mehrhoff University of Connecticut; (c) S. Dewey Utah State University
Common reed replaces native grasses, sedges and herbaceous plants. It provides poor quality habitat for insects, birds and amphibians. Fish populations that reproduce in wetlands and marshes inundated with phragmites suffer higher egg and juvenile mortality. The plant also exudes allelopathic compounds from its roots, causing root death of nearby native plants.