How to Grow Giant Reed

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Giant Reed

Arundo donax

grass

Arundo donax, commonly known as Giant Reed or Spanish Cane, is a tall perennial grass that can reach heights of 15-20 feet, making it one of the tallest grasses in temperate climates. It features broad, bamboo-like leaves and spreads rapidly through rhizomes and viable seeds. While striking in appearance, it is considered invasive in many regions and is now heavily controlled or banned in several areas.

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Example Giant Reed timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Giant Reed

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Giant Reed

    Around Aug 15

    ≈ 120 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Giant Reed dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun, 6+ hours daily; tolerates partial shade
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Water: Moderate to high water needs; prefers consistently moist soil and thrives near water sources such as riverbanks, ditches, and wetland margins
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Spacing: 36 inches
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Days to maturity: 120-180 days (first full season)
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Planting depth: 0.5-1 inch for seeds; rhizome fragments 2-4 inches deep

Soil

Type: Tolerates a wide range of soils; prefers well-draining to moist soils
pH: 6.0-7.5
Amendments:
Compost for moisture retention Sand for improved drainage in clay soils

Growing Zones

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Thrives in zones 6-11, most vigorous in zones 8-10

6a 6b 7a 7b 8a 8b 9a 9b 10a 10b 11a

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Growth Stages

1

Emergence

2-4 weeks

Seeds germinate and small shoots appear with 2-3 leaves; rhizome fragments sprout new shoots from nodes

Keep soil consistently moist; protect young shoots from competition; rhizome cuttings establish quickly if kept moist

2

Vegetative Growth

6-12 weeks

Rapid stem and leaf expansion; plant develops multiple culms (stems) from the base, reaching 3-8 feet tall with broad, arching leaves

Water regularly; provide nutrient support; monitor for competing weeds; thin crowded shoots if desired for single-stem specimens

3

Full Height Development

4-8 weeks

Mature height of 15-20 feet achieved; stems thicken and become woody; extensive rhizomatous root system develops

Continue irrigation during dry periods; no fertilizer needed once established; begin pruning if needed to control spread

4

Flowering

4-8 weeks

Tall, feathery, plume-like panicles (seed heads) emerge at stem tips, typically 1-2 feet long, ranging from whitish to purplish

Flowering occurs late summer through fall; remove seed heads before maturity if invasiveness is a concern; viable seeds are rare in many regions

5

Dormancy & Winter

3-4 months (varies by zone)

Foliage dies back in cold climates; rhizomes remain dormant underground; in warm zones, some evergreen foliage persists

Cut back dead stems in early spring; remove or suppress rhizome shoots that emerge; monitor for unauthorized spread

Companion Planting

Plan your garden →

Plant with:

Willows (for riparian settings) Cattails Sedges Rushes

Avoid planting near:

Native wetland plants Endangered riparian species Agricultural crops (spreads aggressively) Ornamental gardens (difficult to contain)

Common Pests

  • Generally not a serious problem; tolerate minor damage; use neem oil or insecticidal soap if infestations occur

  • Spray with water to dislodge; apply horticultural oils or insecticidal soap if severe

  • Monitor for infestations; apply horticultural oils in dormant season

Uses

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Historical Crafting Material

Craft

Arundo donax has been used historically for making baskets, thatching material, and musical instrument reeds (particularly saxophone and oboe reeds). Its strong, hollow culms make it suitable for various craft applications. [source]

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Biofuel and Biomass Energy

Household

Giant Reed is being researched globally as a potential biofuel crop and biomass feedstock due to its rapid growth, high yield, and ability to grow on marginal lands. Its high productivity per acre makes it attractive for renewable energy applications. [source]

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Ecological Concern & Invasiveness

Wildlife

While Arundo provides dense cover used by some bird species, it is widely recognized as an invasive species that outcompetes native riparian vegetation, reduces biodiversity, increases fire risk, and alters water dynamics. Management and eradication are ongoing priorities in many regions. [source]

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Paper & Pulp Production

Household

Giant Reed has been investigated as a potential source material for paper and pulp production due to its rapid growth rates and high cellulose content, offering a renewable alternative to traditional timber sources. [source]

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Traditional Use in Some Cultures

Medicinal

In certain traditional medicine systems, particularly in Mediterranean and Middle Eastern regions, Arundo has been used for various remedial purposes, though scientific evidence is limited and modern use is minimal. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Giant Reed is not typically harvested for food or ornamental purposes. In regions where it is managed, rhizomes are excavated and removed to control spread; this is labor-intensive and requires repeated efforts. Seeds and vegetative fragments should be destroyed to prevent dispersal. In some research and biofuel contexts, aboveground biomass is cut annually.

Fun Facts

  • 🌱 Giant Reed can grow up to 3 feet per month under optimal conditions, making it one of the fastest-growing plants in temperate regions.
  • 🌱 Arundo donax is so invasive that it now covers an estimated 300,000+ acres in the southwestern United States alone, and it is listed as a noxious weed in multiple states and countries.
  • 🌱 The plant is nearly sterile in most regions outside its native Mediterranean and Asian range, spreading almost entirely through rhizome fragmentation; a single small rhizome piece can initiate a new colony.

Gardening Terms

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