FIRST IMPRESSIONS: Carex platyphylla is a lovely woodland creature with frosty blue foliage that seems to glisten in the shade. This is a petite perennial sedge that forms 1’ clumps of lush shaggy foliage. The leaves are broad by sedge standards and are semi-evergreen. In early-spring, greenish white scaly flower spikes are displayed above the foliage. This sedge prefers partly shaded moist fertile woods but will tolerate average soils and difficult dry shaded sites.
HABITAT & HARDINESS: Carex platyphylla is native to eastern North America. Plants occur from Ontario to Quebec and New Brunswick. In the United States, the greatest distribution extends from Maine to Indiana and south to Tennessee and North Carolina.
Plants are indigenous to rocky woodland slopes, rich moist deciduous woods, calcareous cliffs, ravines and wooded mountainous sites.
This sedge is hardy from USDA Zones 4-8.
PLANT DESCRIPTION: Carex platyphyllla grows in dense clumps of bold strap shaped foliage.
Leaves are shiny with a glaucous powder blue color. Blades have 3 prominent longitudinal veins and are dimpled or puckered along each. Blades emerge from brown leaf sheaths.
Leaves average 1’ long and about 1” wide. Foliage is wider than that of many other sedges and evergreen through most of the range.
In early spring plants bear several culms that sport terminal staminate spikelets with pistillate spikelets below. The greenish white spikelets are widely spaced on the slender culm. Pistillate spikelets contain 2-9 sharply triangular nerved perigynia.
In early summer, the inflorescence browns as achene fruit matures inside the perigynia.
This sedge is about 1’ tall with 1-2’ spread. In flower, the culms rise to around 18”.
CULTURAL & MAINTENANCE NEEDS: Carex platyplylla prospers in moist woodlands especially those with rich calcareous soil. The preferred exposure is light to medium shade. Plants tolerate clay, rocky or alkaline soil and some drought. This sedge will adapt to difficult dry shaded sites.
Plants slowly colonize from short rhizomes and by producing occasional seedlings.
Established plants are pest resistant and unpalatable to deer and other herbivores.
In garden situations, plants should be cut to the ground during late winter before new growth is initiated.
LANDSCAPE USES: Carex platyphylla is a bold textural Accent for Shade Gardens. Plants are used as a Groundcover or as a Border along woodland trails. This sedge is lovely when Grouped or Massed in Wildlife Gardens. Plants provide Erosion Control, Winter Interest and are appropriate for Deer Resistant Plantings, Low Maintenance Plantings or Rock Gardens.
This species is an excellent native substitute for the popular Asian groundcovers Liriope muscari and Ophiopogon japonicus. The unique foliage color allows this sedge to be a suitable substitute for Hosta spp. as well.
COMPANION & UNDERSTUDY PLANTS: Suitable garden companions for Carex platyphylla could include: Aquilegia canadensis, Heuchera americana ‘Dale’s Strain’, Iris cristata and Deschampsia flexuosa.
If a substitute is needed, Carex plantaginea is a look-alike with comparable cultural needs.
TRIVIA: Carex platyphylla and Carex plantaginea are similar in appearance and can be found in the same habitats. Carex plantaginea has red leaf sheaths and lime green leaves. Flowering is later in spring and perigynia are larger. Carex platyphylla has distinctive bluish glaucous leaves with brown sheaths. Flowering is earlier in the spring and perigynia are smaller.
For more information on this plant, visit the USDA PLANTS Database: http://plants.usda.gov/java/profile?symbol=CAPL5