Midwest Noxious Weed: Do Not Plant
Common Name: giant reed
Type: Ornamental grass
Family: Poaceae
Native Range: Mediterranean
Zone: 6 to 10
Height: 12.00 to 20.00 feet
Spread: 5.00 to 8.00 feet
Bloom Time: September to October
Bloom Description: Purple
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Medium
Suggested Use: Water Plant, Naturalize, Rain Garden
Flower: Showy
Tolerate: Black Walnut, Air Pollution
Culture
Easily grown in full sun to light shade a wide variety of soils ranging from light sandy ones to heavy clays. Plants perform well in moist to wet soils including standing water. They also perform well in average well-drained garden soils with some tolerance for dry conditions. In St. Louis, plants will turn brown and die to the ground after fall frost. Cut plants to the ground after frost. Winter mulch will help protect plant roots. Plants may not flower in USDA Zones 6-7 or if they do flower may not produce fertile seed. Plants are easily propagated by soaking pieces of rhizome or stem in water. Root ball may be divided with a spade. For water gardens, plants may be grown in large containers in 1-5” of water in full sun to part shade (best for larger ponds). In frost-free areas (USDA Zones 9-11), plants remain evergreen and will spread aggressively by rhizomes and self-seeding. Pieces of stem or rhizome may float downstream and root in a variety of new locations.
Noteworthy Characteristics
Arundo donax, commonly called giant reed, is a rhizomatous, perennial, warm season grass that sports a somewhat tropical appearance. In mature form, it can make a very bold ornamental statement in the landscape. It is a bamboo-like plant that is native to Europe (primarily the Mediterranean region). It has been widely planted in southern regions of the U.S. for a variety of purposes ranging from ornamental plantings to erosion control. It has naturalized in most states south from northern California to Maryland south to Florida and Arizona. In frost-free regions, it will remain evergreen in winter and will typically grow to 20’ tall. In areas like St. Louis, plants will die to the ground in winter, but can still reach 12’ tall in a single growing season (shorter in average garden soils). Cane-like stems are clad with 2-ranked, smooth, arching, gray-green leaves to 2’ long and 3” wide. Purplish flowers appear in 1-2’ tall narrow inflorescences in fall, aging to silver. Plants may not bloom in climates with early frost.
Genus name comes from the Latin word arundo meaning a reed.
Problems
No serious insect or disease problems. In frost-free climates, giant reed remains evergreen year-round and is usually quite aggressive, especially along ditches or streams or other water bodies. It will outcompete most native vegetation. In St. Louis, giant reed is not invasive. In summer, foliage in tall clumps may lodge to the point where staking becomes necessary.
Uses
Giant reed is best grown as a specimen or accent for border backgrounds or near water bodies. It may be used in large water gardens or along ponds. Young plants can be effectively used as container specimens. Inflorescences are attractive as cut flowers or for dried arrangements. Woodwind instrument reeds are made from stems of this plant.