North America Native Plant

Northern Reedgrass

Botanical name: Calamagrostis stricta inexpansa

USDA symbol: CASTI3

Life cycle: perennial

Habit: grass

Native status: Native to Alaska âš˜ Native to Canada âš˜ Native to Greenland âš˜ Native to the lower 48 states âš˜ Native to St. Pierre and Miquelon  

Synonyms: Calamagrostis californica Kearney (CACA3)  âš˜  Calamagrostis canadensis (Michx.) P. Beauv. var. arcta Stebbins (CACAA3)  âš˜  Calamagrostis canadensis (Michx.) P. Beauv. var. acuminata Vasey ex Shear & Rydb. (CACAA8)  âš˜  Calamagrostis chordorrhiza A.E. Porsild (CACH18)  âš˜  Calamagrostis crassiglumis Thurb. (CACR)  âš˜  Calamagrostis expansa Rickett & Gilly, non (Munro ex Hillebr.) Hitchc. (CAEX11)  âš˜  Calamagrostis fernaldii Louis-Marie (CAFE)  âš˜  Calamagrostis hyperborea Lange var. americana (Vasey) Kearney (CAHYA)  âš˜  Calamagrostis hyperborea Lange var. elongata Kearney (CAHYE)  âš˜  Calamagrostis hyperborea Lange var. stenodes Kearney (CAHYS)  âš˜  Calamagrostis inexpansa A. Gray (CAIN)  âš˜  Calamagrostis inexpansa A. Gray var. barbulata Kearney (CAINB)  âš˜  Calamagrostis inexpansa A. Gray var. brevior (Vasey) Stebbins (CAINB2)  âš˜  Calamagrostis inexpansa A. Gray var. novae-angliae Stebbins (CAINN)  âš˜  Calamagrostis labradorica Kearney (CALA29)  âš˜  Calamagrostis lacustris (Kearney) Nash (CALA47)  âš˜  Calamagrostis lapponica (Wahlenb.) Hartm. var. brevipilis Stebbins (CALAB3)  âš˜  Calamagrostis pickeringii A. Gray var. lacustris (Kearney) Hitchc. (CAPIL2)  âš˜  Calamagrostis robertii A.E. Porsild (CARO27)  âš˜  Calamagrostis stricta (Timm) Koeler var. brevior Vasey (CASTB3)  âš˜  Calamagrostis stricta (Timm) Koeler var. lacustris (Kearney) C.W. Greene (CASTL3)   

Northern Reedgrass: A Hardy Native Grass for Wet Garden Spaces If you’re looking for a native grass that thrives in moisture-rich areas and provides subtle beauty throughout the growing season, northern reedgrass (Calamagrostis stricta inexpansa) might just be the perfect addition to your landscape. This resilient perennial grass brings both ...

Rare plant alert!

Region: Conservation status by state

Status: S1Q: Status is uncertain but is somewhere between the following rankings: Uncertain taxonomy: ⚘ Critically Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 5 or fewer occurrences or very few remaining individuals (<1,000) ⚘ Uncertain taxonomy: ⚘ Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘ Uncertain taxonomy: ⚘ Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘

Region: Conservation status by state

Region: Conservation status by state

Northern Reedgrass: A Hardy Native Grass for Wet Garden Spaces

If you’re looking for a native grass that thrives in moisture-rich areas and provides subtle beauty throughout the growing season, northern reedgrass (Calamagrostis stricta inexpansa) might just be the perfect addition to your landscape. This resilient perennial grass brings both ecological value and quiet charm to gardens across much of North America.

What is Northern Reedgrass?

Northern reedgrass is a native perennial grass that forms dense, rhizomatous clumps. As a member of the grass family, it’s perfectly adapted to cooler climates and wet conditions. This hardy plant grows in an upright, erect form and can reach up to 3 feet tall at maturity, making it an excellent choice for adding vertical interest to your garden without overwhelming smaller plants.

The grass produces modest purple flowers in late spring, though they’re not particularly showy. What really makes this plant shine is its dark green foliage that provides dense coverage in summer and becomes more open and airy in winter, creating seasonal interest in the garden.

Where Northern Reedgrass Grows Naturally

This remarkable grass has one of the most extensive native ranges you’ll find, naturally occurring across Alaska, Canada (including all provinces and territories), Greenland, and throughout most of the lower 48 states. From the Arctic tundra to temperate wetlands, northern reedgrass has adapted to thrive in diverse climates and conditions.

Why Grow Northern Reedgrass?

There are several compelling reasons to consider adding northern reedgrass to your landscape:

  • Excellent for wet areas: With its high moisture requirements and tolerance for anaerobic conditions, it’s perfect for those soggy spots where other plants struggle
  • Long-lived perennial: Once established, this grass will provide years of reliable performance
  • Cold hardy: Tolerates temperatures down to -38°F, making it suitable for even the most challenging northern climates
  • Low maintenance: Moderate growth rate means less frequent division or management
  • Erosion control: The rhizomatous root system helps stabilize soil in wet areas

Important Conservation Note

Before planting northern reedgrass, it’s important to know that this species has varying conservation statuses across its range, with some populations considered rare or of special concern. If you’re interested in growing this grass, make sure to source your plants or seeds from reputable native plant nurseries that use responsibly collected material. Never harvest from wild populations.

Garden Design and Landscaping Uses

Northern reedgrass works beautifully in several landscape applications:

  • Rain gardens: Its high moisture tolerance makes it ideal for managing stormwater runoff
  • Pond margins: Creates a natural transition from water to upland areas
  • Wetland restoration: Essential for authentic native wetland plantings
  • Naturalized areas: Perfect for meadow-style plantings and wildlife gardens
  • Erosion-prone slopes: Particularly effective on wet slopes that need stabilization

Growing Conditions

Northern reedgrass is surprisingly specific about its preferred growing conditions:

  • Soil: Prefers fine to medium-textured soils; avoid sandy or coarse soils
  • Moisture: Requires consistently high moisture levels
  • pH: Tolerates a range from 5.5 to 8.0 (slightly acidic to slightly alkaline)
  • Light: Does well in partial shade to full sun
  • Temperature: Extremely cold tolerant but needs at least 90 frost-free days
  • Precipitation: Thrives with 26-60 inches of annual precipitation

Planting and Care Tips

Getting northern reedgrass established successfully requires attention to a few key details:

Planting: This grass is typically propagated by seed or sprigs rather than transplants. Seeds can be sown in spring, but don’t expect quick results – seedling vigor is relatively low, so patience is key.

Spacing: Plant 11,000-18,000 plants per acre for restoration projects, or space individual clumps about 2-3 feet apart in garden settings.

Establishment: Keep soil consistently moist during the establishment period. The grass has a slow to moderate spreading rate, so don’t expect immediate coverage.

Maintenance: Once established, northern reedgrass is relatively low-maintenance. It has slow regrowth after cutting, so avoid frequent mowing. The grass is not fire-resistant, so take precautions in fire-prone areas.

Seasonal Interest

Northern reedgrass provides subtle but reliable seasonal appeal:

  • Spring: Fresh green growth begins the active growing season
  • Late Spring: Modest purple flower heads appear
  • Summer: Dense, dark green foliage provides lush coverage
  • Fall: Becomes conspicuous as other plants die back, seed heads turn brown
  • Winter: Dormant foliage becomes more open, creating winter texture

Is Northern Reedgrass Right for Your Garden?

This native grass is an excellent choice if you have consistently wet areas that need attractive, low-maintenance coverage. It’s particularly valuable for gardeners interested in supporting local ecosystems with authentic native plantings. However, it’s not the right choice for dry gardens, formal landscapes, or areas where you need quick establishment.

Remember to source your plants responsibly and be patient with establishment. Once settled in, northern reedgrass will reward you with years of quiet beauty and ecological function in your wet garden spaces.

Northern Reedgrass

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Commelinidae

Order

Cyperales

Family

Poaceae Barnhart - Grass family

Genus

Calamagrostis Adans. - reedgrass

Species

Calamagrostis stricta (Timm) Koeler - slimstem reedgrass

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA