Grasses and Their Habits

Ornamental Grasses come in all shapes and sizes and types; for the most part, they do best in full to part sun and are generally not fussy about soil types.  They are generally very attractive when left standing in the winter garden, to be cut down in earliest spring.  They are either Warm Season or Cool Season grasses.

Warm Season Grasses will NOT push growth in the spring until the weather has turned reliably warm; they often reach their peak during the dog days of summer and generally do not bloom until late summer or fall.

Cool Season Grasses, like many herbaceous plants grow slowly through the winter and burst into the early spring landscape; reaching their prime in mid-late spring; pushing delicate blooms into the spring border.  Though some Cool Season grasses sulk in the heat of summer, several perform well all through the year, Calmagrostis and Blue Oat Grass are two such.

All Warm Season grasses should be left up and enjoyed through the winter then cut back as early as possible in early spring.  They look well when interplanted with spring bulbs; spacing grasses at least 3’ apart provides room for a succession of spring blooms (crocus, followed by daffodils, then tulips and allium) which will begin their die back as the grasses take off on their meteoric rise.

Miscanthus (Warm Season Grasses)

Miscanthus sinensis - the species form of Miscanthus; 6-7’ tall, vase shaped, a splendid specimen or dense hedger.  Prefers full sun, but will tolerate a bit of shade.  Plant at least 5’ on center.  Bloom in late summer-fall.  Frost blanches the grass and seed heads to pale gold, particularly handsome against evergreens in winter.

Miscanthus gracillimus - Graceful Maiden Grass – has long, arching, fine foliage with 7’ blades that form a 4-5’ fountain.  Flowers, white and fan-shaped emerge in October.

Miscanthus “Morning Light’ – a delicate grass that forms 4’ clumps of silvery green.  Great with silver-leaved and other pastels.  Bloom and color change as above.

Miscanthus “Silberfeder’ – like the species in size, is not as finely textured as gracillimus; 6-7’ tall; very hardy, with shimmering, white fan-shaped blooms as early as August.

Miscanthus sinensis strictus and zebrinus – bright green with yellow, horizontal bands that are best in full sun.  Strictus is the most upright of the two, fanning out in October.  Zebrinus is faster growing but tends to sprawl a bit, falling open in the middle.

Miscanthus sinensis variegata – Clean, distinct green and white vertical stripes make this a unique grass, stunning as a specimen in a container; against a dark background like ground cover or in the border.  Growth habit similar to the species.  Tolerates a little shade, but will flop if it gets too much.

Panicum – Switch Grass – (Warm Season Grass)

A north American native that may get 6’ high, but more commonly 4-5’; roots may be twice as deep as the grass is high!! Very tough, withstands drought, temperature extremes, and various soil types.  Clouds of blooms over green, airy grass in mid summer.  After frost, the entire plant stiffens into a vertical, wheat colored pillar effective throughout the winter.  Cut back in early spring.

Haense Herms – 3-4’ tall, very upright with red blooms and seed heads in late summer-early fall; frost fades the color from red to pale gold.

Heavy Metal – 3-4’ with stiff metallic blue foliage, forming a tight, upright clump.  Bright yellow after frost.  Effective as specimen or in mass.  Full sun for best color and shape.

Pennisetum – Fountain Grass (Warm Season Grass)

Full sun, forming dense, graceful hemisphere up to 36” tall.  Attractive June through March when it should be cut back.  Forms buff colored flower heads, about 6” long in late summer.  Seed heads remain on the plant late into winter.  Great addition to the winter garden.

Hameln – dwarf form at 24”; similar to the species in every other way.

Little Bunny – a 12” form of the species.

Helictotrichon Sempervirens - Blue Oat Grass (Cool Season Grass)

Showy from earliest spring, through the winter; can be cut back in late winter to show the true-blue blades of new grass to best advantage; a strict clump former; needs full sun, likes good drainage; reliably good looking; Great in the perennial or shrub border.

Calamagrostis – (Cool Season Grass)

Effective even in summer, yet quick to emerge after winter, growing to 4’; producing airy, delicate 12” long flowers in June that remain above the plant through the year.  A very vertical grass; useful for low-screening, as a background mass or as a specimen plant.  One of the best all round grasses, and easy, since it is not fussy about soil type, moisture or temperature.  Will tolerate some shade, but may flop a bit.

“Karl Foerster” 3-5’ calamagrostis.

“Overdam” – 3’ green and white variegated grass with 36” inflorescences in summer.  Excellent accent plant; sun or part-shade.

Erianthus Ravennae (Saccharum Ravennae - Ravenna Grass – (Warm Season Grass)

Sometimes called the hardy pampas grass, is the largest and most striking of the cold-hardy ornamental grasses; 1” wide leaves form basal mounds to 4’; in late summer large plumy flower stalks rise 10-14’ .  Late summer and fall assumes reddish color in stems and foliage; very drought tolerant once established.  Rarely needs division.

Imperata Cylindrica – Japanese Blood Grass (Warm Season Grass)

“Red Baron” is a slow spreader with 20” leaves that are green at the base and increasingly red at the top as the season progresses.  Color fades with hard frost.  Since winter interest is negligible, cut back in fall.  Drought tolerant once established and tough enough for groundcover use in challenging sites such as parking lot islands.  Dramatic in sweeps and masses, particularly when back lighted by the sun.

Be wary of:

Phalaris picta, aka Ribbon Grass or Gardeners Garters – a delightful looking little thug that can spread rampantly by runner and by seed.  However, if grown in poor, sterile, dry soil in the sun, it will become a dense, good-looking 1-2’ mass of green and white; cool weather grower; so cut back in mid-summer to refresh the look and retard formation of seed heads.

Blue Fescue – a charming tuft of blue spikes with delicate florescences in early summer; readily self-seeds which is not a problem when it is near a regularly mowed lawn, but can be problem when planted near a driveway or other open space.

The Sales Pitch

Grasses are an elegant, nearly carefree, graceful addition to any landscape.  They change as the year progresses, thus lending your garden an ever-changing look; they are great accents to almost any plant; they serve architectural functions, providing walls to diffuse noise and dirt as well as visual privacy in the summer.

And, and, and ......they are a glory on a snowy, cold winter day.  They provide habitat and food for birds; and the sound they make in the wind is soft and delightful.  In short, we love them alone, with evergreens, in large drifts and as part of the perennial border.