common threesquare
Schoenoplectus pungens · Cyperaceae
common threesquare (Schoenoplectus pungens) is a perennial grass or grass-like plant in the Cyperaceae family. It is native to North America. USDA records it as hardy in zone 3 and warmer, down to about -38°F.
At a glance
| Type | graminoid USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 4.9 ft USDA |
| Light | full-sun USDA |
| Water need | high USDA |
| Growth rate | moderate USDA |
| Soil pH | 3.7–7.5 USDA |
| Bloom | May–June USDA |
| Flower color | Blue USDA |
| Hardiness zones | 3 and warmer USDA |
| Guild layer | herb-layer Derived |
| Nursery availability | Routinely Available USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It needs full sun. USDA rates it as having needs consistently moist ground. Its drought tolerance is rated low. It tolerates saturated, poorly drained ground well (USDA rates its anaerobic tolerance high). It is recorded on soils from pH 3.7 to 7.5 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 3.
Size and growth
At maturity it reaches about 4.9 ft, making it roughly waist to chest height. It grows at a moderate rate.
Bloom period
USDA records a bloom period of May through June. Flowers are blue.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is dark green, coarse in texture. Its flowers are not conspicuous — a plant for form and foliage. Its active growth period is summer. USDA rates its lifespan as long.
What the site needs to provide
USDA records it across sites receiving 12 to 60 inches of annual precipitation. The low end of that band is genuinely arid, so it has a wide tolerance for dry country. It needs at least 120 frost-free days to finish its season. It roots to at least 14 inches. Fertility requirement: medium.
Propagating it
Sprigs is the only propagation method USDA lists. Its seed spreads at a moderate rate. It spreads vegetatively at a moderate rate.
Resilience and wildlife
Its fire tolerance is rated medium. Its growth form is recorded as rhizomatous.
Role in a guild
Herb layer. In a layered planting this is the herbaceous middle — perennials and grasses that fill the space between ground cover and shrubs. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Schoenoplectus
- hardstem bulrush Schoenoplectus acutus
- California bulrush Schoenoplectus californicus
- slender bulrush Schoenoplectus heterochaetus
- softstem bulrush Schoenoplectus tabernaemontani
Similar role and hardiness
- sweetflag Acorus americanus
- calamus Acorus calamus
- common yarrow Achillea millefolium
- western yarrow Achillea millefolium
- redtop Agrostis gigantea
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol SCPUP5, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
- Quoted from USDA PLANTS: active growth period, Bloom, Bloom end, cold stratification, Drought tolerance, fall conspicuous, fertility requirement, fire tolerance, Flower color, flower conspicuous, foliage color, foliage porosity winter, foliage texture, frost free days min, fruit conspicuous, growth form, Growth rate, Hardiness zones, Lifecycle, lifespan, Light, Mature height, Minimum temperature, Native status, Nitrogen fixation, Nursery availability, precipitation max in, precipitation min in, propagation, resprout ability, root depth in, seed spread rate, Soil pH, Soil pH (upper), Tolerance of wet soil, Toxicity, Type, vegetative spread rate, Water need.
- Derived by a fixed rule from those columns: Guild layer.
Read our full data sources and methodology.
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