Giant Reed (Arundo donax)

How much light does a Giant Reed need?

Full sun is the preferred exposure for giant reed, meaning six or more hours of direct sunlight a day. Part shade is also listed as an acceptable condition. Both full sun and part shade appear in the listing, and full sun comes first. Light levels beyond those two are not documented.

• Light: Full sun and part shade (full sun preferred)¹

How often to water a Giant Reed

Water needs for giant reed run from medium to wet. The plant has high water use and grows best near water. The driest level listed is medium, and the wettest is wet. No cited source gives a watering schedule in days, so no schedule is stated here.

• Water: Medium to wet^2,3

Best soil for a Giant Reed

Moist and occasionally wet soil suits giant reed. Those are the two drainage classes listed for the plant. That pairs with a water range of medium to wet. When you inspect a planting site, look for ground that is moist and sometimes wet. No cited source records a soil pH range for giant reed, so none is given here. Nor does any cited source name a soil texture such as sand, loam or clay.

• Soil drainage: Moist and occasionally wet²

Hardiness and temperature

Hardiness is listed as USDA zones 5a to 10b. That covers twelve steps: 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a and 10b. Zones 11 and warmer fall outside the listed range. No cited source records a minimum temperature or a humidity preference for this plant. Use your zone, not a single temperature figure, to judge whether it suits your garden.

• Hardiness: Zones 5a–10b¹

How to plant a Giant Reed

Allow room for a mature height of 14 to 30 ft (4.27–9.14 m) and a width of 5 to 9 ft (1.52–2.74 m). Choose a site in full sun or part shade, with moist soil that is occasionally wet. The listed hardiness range is 5a to 10b, so confirm your zone before you plant. Its growth rate is rapid, which is worth keeping in mind when you pick the spot. No cited source gives a planting date or a spacing between plants, so none is stated.

• Hardiness: Zones 5a–10b¹

Winter care

Zone 5a is the coldest zone listed for giant reed, and 10b is the warmest. Gardens in zone 4 or colder fall outside that range. No cited source records a minimum temperature, so no freezing threshold is given. No cited source describes winter protection, mulching or cutting back.

• Hardiness: Zones 5a–10b¹

How to propagate a Giant Reed

Division is the recommended propagation strategy for giant reed. Division is the only method listed for this plant, so seed and cuttings are not covered here. No cited source describes the timing or technique, so this page gives no steps for dividing a clump.

• Propagation: Division⁴

Common problems

A wasp named Tetramesa romana was approved for release by the US Department of Agriculture in 2009. A scale insect was also being considered for biological control. Aphids are the third pest recorded for this plant. No cited source lists diseases for giant reed.

• Common pests: arundo wasp, armored scale and aphids^2,2

Questions and answers

How big does giant reed get?

A mature plant grows 14 to 30 ft (4.27–9.14 m) tall and 5 to 9 ft (1.52–2.74 m) wide. Its growth rate is rapid, and it is described as a tall, fast-growing, bamboo-like grass.

When does giant reed bloom, and in what colors?

The listed bloom time is July–August and September–October. Flower colors are brown, pink and red. No cited source describes the size or shape of the flowers.

Is giant reed native to the United States?

The native-status record lists giant reed as introduced in the lower 48 states, Hawaii and Puerto Rico. The native range record includes regions such as India (IND), Iran (IRN), Japan (JAP) and Turkey (TUR).