Panicum virgatum 'Thundercloud'

Thundercloud switchgrass    Perennial of the Month-- November 2015 Perry caricature

 (pronunciation at link)   (pan-eh-come'  veer-gA' tum)

Common name: Thundercloud switchgrass

Family:  Poaceae, grass

Height x width: 6-8ft x 3-5ft.

Growth rate, habit: moderate, upright vase-shape

Foliage: leaves glabrous, glaucous, entire, flat, alternate; 2-3ft long and 1/2 to 3/4in. wide; about 7 to 8 leaves per stem (culm)

Flowers:  open, finely branched, sturdy, non-flopping; one per culm, beginning mid-July turning pinkish-tan, persist into winter; panicles 12-15in. long and slightly less wide

Hardiness: USDA hardiness zones 4-9 (average minimum -20 to -30F in winter)

Soil:  average; once established tolerates wet to dry soils, drought tolerant so good for low-water gardens

Light:  full sun best, tolerates part shade

Pests and problems:   none significant, can be weak and topple in too much shade

Landscape habit, uses:  specimen, borders, meadows, wild or naturalized gardens,native plant gardens, rain gardens, along watersides, wildlife gardens (cover and food for birds), massed for formal effect,  screening or informal hedge, large containers, cut or dried; combines well with asters, yarrows, tall garden phlox, false indigo, Shasta daisy, rudbeckia, tall sedum, Joe-pye, Karl Foerster feather reed grass (blooms earlier)\; a good native grass substitute for Miscanthus

Other interest: a hybrid from Amber Wave Gardens (Gary Trucks) in western Michigan in 2002 between 'Cloud Nine' and 'Northwind'; leaves are wider and bluer than the parents; similar to 'Dallas Blues' or 'Heavy Metal' only with more open flowers, taller, bluer; common name from swishing sound in the wind; tolerates environmental salt; since a warm season grass may be slow to emerge in the spring in northern climates; native to much of the U.S. except the far west coast, species was important in tallgrass prairies

Other culture:   cut back clumps to 6-12in. from ground in late winter or early spring prior to growth resuming; can live up to 15 years under ideal conditions; fertilize sparingly, or none may be needed if a rich soil with compost

Propagation:  USPP20665 so commercially by licensed propagators; at home by spring division as needed

Sources:  many online and local specialty nurseries



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