Key Facts
- A tall perennial cane grass in the grass family
- Often forms dense colonies by spreading rhizomes
- Commonly found in riparian and wet sites
- Produces plume like flower panicles in late summer to fall
- Regarded as invasive in many warm temperate and Mediterranean climates
- Prefers full sun and moist soils but tolerates poor drainage and some salinity
- Usually propagated by rhizome or stem cuttings rather than seed
- Often dies back in cold winters but resprouts from underground parts
Giant Reed, Arundo donax, is a very large perennial cane grass that commonly grows in wet ground and along waterways. It is used as a tall screen or specimen plant but carries a high risk of becoming invasive in warm climates where it spreads by rhizomes.
Identification
Canes commonly reach 6 to 20 feet tall and sometimes grow taller where water is abundant. Leaves are long and grasslike and the plant produces plume like flower panicles in late summer to fall. Plants form dense clumps that merge into larger colonies over time.
Where to grow and best uses
Grows best in full sun to light shade and prefers moist to wet fertile soils. It tolerates poor drainage and some salinity and becomes less vigorous in very dry soils. Use as a tall screen or an accent reed along ponds and other wet margins but weigh the aesthetic value against the strong potential to displace native plants.
Hardiness and size
Reported hardy in USDA zones 7 to 10. Above ground canes often die back in colder locations and resprout from underground parts in spring. Expect mature clumps to be roughly 1 to 3 meters across and colonies to expand beyond that if left unchecked.
Planting and propagation
Propagate by dividing rhizomes or using stem or cane cuttings. Seed propagation is uncommon in many introduced areas and spread is usually vegetative. When moving or planting material take care to avoid leaving stem or rhizome fragments in the soil because they can regenerate.
Watering and maintenance
Establish plants with consistent moisture and allow them to show their mature form in wet, sunny spots. Once established they tolerate occasional dry periods but perform best with steady moisture. Remove dead canes each year to keep clumps tidy and monitor surrounding areas for new shoots.
After flowering and managing size
Flower panicles appear in late summer to fall. Cutting back spent canes reduces visual bulk and may help manage spread but does not prevent regrowth from rhizomes. Long term control requires regular monitoring and removal of new shoots at the colony margin.
Controlling spread and risks
Arundo donax is regarded as invasive in many warm temperate and Mediterranean climates and can displace native vegetation along waterways. It spreads mainly by rhizomes and by stem fragments that can resprout. Before planting check local invasive species rules and riparian guidance and plan for careful disposal of removed material.
Frequently asked questions
- How fast does Giant Reed grow?
- In warm wet sites canes can reach their mature height within a single growing season and colonies expand over years as rhizomes spread.
- Is Giant Reed invasive?
- Yes it is regarded as invasive in many warm temperate and Mediterranean regions and can displace native plants along waterways.
- Will it regrow after cutting or winter dieback?
- Yes canes commonly resprout from underground parts after cutting or after winter dieback in cooler climates.
- What is the easiest way to limit spread?
- Prevent movement of rhizome and stem fragments, remove new shoots at the colony edge and follow local recommendations for managing invasive riparian plants.
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