Panicum amarum 'Dewey Blue' - Dewey Blue Bitter Panicgrass, Bitter Switch Grass

Ornamental grass expert Rick Darke found this grass growing in sand dunes near Dewey, Delaware. He then selected the bluest one and named it P. 'Dewey Blue'.

It is often found growing along salt-water coastlines, abandoned railroad tracks and in other difficult areas. With its preference for sandy soil, and it salt tolerance, it is used extensively to help stabilize sand dunes.

Ìt has an upright arching or fountain-like growth habit. Height and form varies depending on the soil fertility and the amount of moisture. It prefers less fertile, drier soils. If the soil is fertile and moist, it may have problems remaining upright.

Flowers are more numerous than those displayed by Panicum virgatum, and are larger. The seeds are loved by birds.

Description: warm season*; spreader, but easy to control
Foliage is blue, 90-120 cm (36-48") in height
Flowers Aug through Sept; 120-150 cm (48-60") tall

Ideal conditions: full sun; prefers average to dry sandy soil with good drainage

Coldest zone: 4 (find your zone; further info on plant hardiness)

Partner with: Coreopsis tripteris, Solidago 'Strahlenkrona', Inula racemosa 'Sonnenspeer', Calamagrostis epigejos

Season of interest: August to winter

Drought tolerance rating: 2 (water to root depth once every 2 weeks); further info

The species is native to: sand dunes from Connecticut, USA to Mexico

Recommended spacing between plants: 50-80 cm (20-32") why such a difference?

When to divide: when it shows signs of life in the spring, continuing until the new growth is about 12" tall; only in the spring (further info on dividing grasses)

When to plant or transplant: plant bare root plants only in late spring to early summer, when the soil is warm, about the same time you plant your bean or corn seeds. The roots will grow only in warm soil. Planting too early in the spring may cause the roots to rot. Similar story in the fall when the roots may not grow enough to establish before the cold and wet of winter, resulting in the demise of the plant.

When to cut back: before the new growth starts to appear, but after the cold weather is over. Cut back to about 3-4" from the crown of the plant.

Pronunciation: Panicum (PAN-ih-kum) amarum (ah-MAR-um)


*a warm season grass likes to grow in warm weather. Before it will show signs of life in the spring, the soil must warm up, and be warm for possibly as long as two weeks.

More ornamental grasses

Compare Panicum amarum 'Dewey Blue' to our other grasses in this handy chart.


Panicum amarum
Panicum amarum - Bitter Panicgrass
Photo credit: USDA-NRCS PLANTS Database


from the USDA website: States
where Panicum amarum is native