Carex Flacca: Blue Sedge Information and Care

Carex Flacca, or Blue Sedge, is a beautiful grass with slender arching leaves. Why should you consider it and how to grow it?

Carex flacca, or Blue Sedge, is a beautiful European variant of evergreen sedge. It forms a cluster of slender arching leaves that are blue-green on top and glaucous-blue on the bottom. It has tiny, short brown flower spikes in early summer that are erect initially but gradually nod over.

The genus name Carex refers to the pointed leaves and stems edges found on most plants in the genus. Carex flacca results from years of confusion between these various names for the same plant. 

It’s been marketed as Carex glauca in the United States for decades, and that’s the name we’ve listed it under since we started cultivating it in 1986 with plants obtained from the Grassman, John Greenlee. 

Carex flacca is the proper name for this plant. However, the version marketed in nurseries for many years is a beautiful glaucous, a range of pale colors from a yellow-green to a bluish-gray variety. 

Continue reading to learn more about this amazing plant.

General Information

Carex flacca is a Mediterranean native found in calcareous grasslands, marshes, sand dunes, and coastlines in southern Europe and North Africa. Because of its leafy appearance, it is commonly used as a ground cover in landscapes. Little blooms appear early in the summer on terminal, cylindrical spikes of 12 inches tall.

Blue Sedge quickly grows to 6 to 12 inches tall and 12 to 18 inches wide. The rhizomes of this plant will spread over time to form a dense ground cover. Because of their adaptability, the grasses can be used in various settings, such as containers, baskets, raised beds, borders, and rockeries.

Flaca grass along the passageway with some rocks

Care and Maintenance

Carex flacca can be started from seed in a cold frame in the spring or divided in the early summer. They thrive in alkaline to neutral soil that retains moisture. This plant is also drought-resistant once established. 

It makes a lovely low-growing ground cover in the sun or partial shade. It has slender, bluish-gray foliage that grows 6 to 8 inches long and has a nice, disheveled appearance.

Fertilization is also recommended when growing this perennial because young plants require extra phosphorus for proper root growth. Fertilizer options are water-soluble, quick-release, temperature-controlled, slow-release, and organic fertilizers such as fish emulsions.

Carex flacca thrives under various conditions and can be grown in average, moist, well-drained soil. It spreads slowly via rhizomes, which can be aided by light pruning. Early spring mowing at 4 inches (possibly once or twice more per year) keeps this plant healthy and gives it a more trimmed, neat appearance. Clumps are easily split between the spring and early autumn.

closeup picture of the grass flowers

How to Use it in Landscapes

Carex flacca is a lovely sedge with lovely arching foliage that bends and bows like new paint, providing a luscious, green coating of color. It’s frequently used as a strong accent in mass plantings. It’s also a lovely edging plant for pond banks, perennial gardens, and a ground cover for pathways, pavements, and sloping banks. It’s important to remember that it can spread, so it’s best grown in small spaces.

Companion Plants

Try this simple yet elegant combination of succulents and perennials as a lovely companion plant for your Carex flacca!

Carex flacca’s (Blue Sedge) highlights contrast nicely with the sunset color of Euphorbia tirucalli (Fire Sticks) and the copper tones of Sedum nussbaumerianum (Stonecrop). It also goes well with Agave attenuata (Blue Glow) and Senecio mandraliscae (Blue Chalk Stick), which has a lovely blue-gray tint. Furthermore, the crisp symmetry of the agaves contrasts with the loose appearances of Senecio mandraliscae and Euphorbia tirucalli, as well as Carex flacca’s cascading mounds of arching leaves.

1. Euphorbia tirucalli (Fire Sticks)

Euphorbia tirucalli, Sticks on Fire, is a lovely evergreen succulent shrub with a tangle of brightly colored, loose vertical branches that look like sea coral. The distinctive stems are as thin as pencils, with a reddish-golden hue that fades to yellow in the summer before returning to reddish-orange tones in the winter. The stems have small, inconspicuous leaves that fall off quickly when young. 

Landscape designers adore Euphorbia tirucalli, which they use to create succulent seascapes, add vertical highlights to waterwise gardens, and add flaming color to container flower displays.

Euphorbia plant with leaves looking like fire sticks

2. Sedum nussbaumerianum (Coppertone Stonecrop)

Coppertone Stonecrop (Sedum nussbaumerianum) is a low-growing evergreen perennial shrub with lovely rosettes of thick pointed leaves that mature to about 2 inches long. The leaves are yellow-green in the shade but turn rosy-gold to vivid coppery red in the sun. Round clusters of faintly aromatic white blossoms with pink anthers emerge in the spring. It is an excellent choice for a succulent or rock garden and is lovely in a container or hanging basket.

3. Agave attenuata (Blue Glow)

The slow-growing evergreen succulent Agave attenuata has magnificent rosettes of blue-green chalk leaves with beautifully serrated edges and a golden and crimson ribbon embellishing the margins. This beauty is especially appealing when its flaming red and golden edges are backlit by light.

It will take over ten years for this Agave to bloom. It will then expire, leaving no offsets. This hybrid combines Agave attenuata’s gorgeous leaves with Agave ocahui’s smaller size, solitary habit, and terminal spine. It can be used as a dramatic focal piece or stunning accent in containers.

agave attenuata ornamental plant in the garden

4. Senecio mandraliscae (Blue Chalk Stick)

Senecio mandraliscae (Blue Chalk Sticks) is a South African native with 3 to 4 inch long silvery blue finger-like leaves and little white buds in the summer. With its upward-curving leaves, this low-growing succulent quickly produces a thick blue mat, making it ideal as a border plant or groundcover. It’s also great for creating a low, blue-edged border.

Jeffrey Douglas
Jeffrey Douglas own a landscaping company and has been in the business for over 20 years. He loves all things related to lawns or gardens and believes that proper maintenance is the key to preventing problems in the first place.
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