Juncus patens
Spreading Rush, aka Spreading Blue Rush or Paten’s Rush, is easily recognizable by the lovely blueing hue of its evergreen, architectural foliage. This plant really pops, adding year-round visual interest to sunny areas with ample moisture, such as a raingarden - while helping to control erosion. In summer, it creates small clustered brown inflorescence that are utilized by some birds.
- Plant type/canopy layer: evergreen, herbaceous plant
- Size at maturity: 1-2' tall, 1-3' wide
- Light requirements: full sun, part sun/part shade
- Moisture requirements: moist to wet soil
- Bloom time: June - July
- Growth rate/ease: fast growth rate, easy to grow
- Wildlife support: attracts and supports beneficial and other pest eating insects, caterpillar host plant/larval food source
- Native habitat/range: Common along shores, and in floodplains, wet prairies, wet forests, swales, marshes, and ditches up to 1000 meters from western Washington, through western Oregon and south to Mexico. Portland Plant List - yes.
- Special features & uses: raingarden/bioswale, evergreen, erosion control
Gardening with Spreading Blue Rush: This plant is truly a joy to design with. Commonly described with terms like “modern”, “minimalist” or even “mid-century”, it adds architectural interest to sunny, wet areas of the garden and is becoming increasingly common in mainstream landscape design - especially in cities like Portland where the city often requires native plants in new development. This is great because it also has lots of ecological value from controlling erosion to providing insect/arthropod habitat.
That said, unfortunately it is also common to see this (and many) native plants maintained in aggressive, “blow-and-go” fashion that strips them of their ecological benefits; like cutting back all of the vegetation on the rushes at the end of the growing season. If you intend to build a backyard habitat, start with maintaining your plants in a low-impact way that supports insects (aka, leave them be). One of the greatest habitat values of native grasses, sedges and rushes is the insect/arthropod nesting habitat created in the areas where the foliage flops over onto the ground. Trimming this off diminishes the ecological value and can even create ecological sinks by interrupting their life cycles and destroying overwintering nests, larva, eggs, etc.
Photo Credit 1 & 2: Nikkie West, Sparrowhawk Native Plants
Photo Credit 3: "Juncus patens (spreading rush) approximately 6 months after being planted" by oliveoligarchy is licensed under CC BY 2.0