Ornamental grasses fall into 2 categories - warm season and cool season species. Cool season grasses emerge when the soil temperature is between 50-65 degrees (usually in April.) They grow rapidly and flower in spring/early summer, then go dormant during the July/August heat (though they will still look good). In the early fall, they get a second flush when soil temperatures drop again. Conversely, warm season grasses take their time getting up in the spring. They like soil temps between 70-90 degrees and will start to green up in May and come into flower during the heat of summer. Some warm season grasses, like several Miscanthus cultivars, won't flower until the fall. Many will stand tall all winter long.
landscape design that incorporates both cool and warm season grasses
will provide year-round interest.
Cool Season Grasses
Calamagrostis x acutiflora 'Avalanche' (Variegated feather reed grass) 'Avalanche' is a show-stopping, variegated form of 'Karl Foerster,' featuring green/blue blades with a bright white stripe. Smaller than 'Karl Foerster', and though it's flowers tend to be a bit less stable than its larger cousin, its foliage is far brighter. 'Avalanche' can tolerate some light shade and prefers a moist soil when first planted. Foliage grows to about 2.5 feet. Flowers to 4-5 feet in late June/early July.
Calamagrostis x acutiflora 'Karl Foerster' (Feather reed grass) The 2001 Perennial Plant of the Year for good reason. Beautiful, tough, low maintenance and sways gracefully in even the lightest breeze. Extremely versatile, it can be used as a screen or in the back of garden beds. 'Karl Foerster' is one of the first ornamental grasses to green up in the spring and its wheat-like fall flowers last late into the year. Foliage reaches about 2 feet with flowers hitting up to 6 feet. Flowers emerge in late June/July as purplish plumes, becoming increasingly narrow and tan as they age. A real winner.
Deschampsia cespitosa (Tufted hair grass) Deschampsia is an easy to grow cool season grass that emerges with spiky and nicely mounded foliage. In late June, airy sprays of flowers are held high above the foliage. Can be used as a specimen or looks fantastic in masses, forming soft clouds of pale flowers that float above the row. Deschampsia flowers best in full sun. We cut the flowers on Deschampsia before they dry to keep reseeding to a minimum.
Festuca glauca 'Elijah Blue' (Blue sheep's fescue) Striking silver blue foliage combined with reliable performance puts 'Elijah Blue' at the top of the list for edging and front of border plants. Wants well-drained soil and likes full sun. Tougher and longer lived than other blue fescues. Foliage gets to 10-inches with 5-inch arrow-straight flowers maturing from blue in early June to tan in the summer. Cut back in March or April to 2-3 inches and divide yearly to keep foliage looking fresh.
Hackonechloa macra 'Aureola' (Golden variegated Japanese forest grass or Hakone grass) and 'All Gold' 'Aureola' was the 2009 Perennial Plant of the Year and a recipient of the Royal Horticultural Society's Award of Garden Merit. Soft, weeping form and striking color looks best in mostly shade, where its gold variegated leaves stand out. Slow growing, but worth the wait. 'All Gold' is a bit less fussy than 'Aureola' and features bright yellow foliage that really likes up the shade border. Both varieties like fertile, moist and well-drained soil. Insignificant flowers.
Warm Season Grasses
Chasmanthium latifolium (Northern sea oats) One of our favorite grasses. A U.S. native that features bamboo-like foliage and beautiful seed heads that quake in the breeze. Particularly captivating when its panicles are backlit by the sun. Can grow in sun or shade, in wet or dry. A very versatile, loosely tufted grass - use in sweeps or as an accent. Can be naturalized or used as a groundcover. In autumn, the green foliage turns a pinkish copper color. Tends to self-seed, but seedlings are easily pulled. Grows to 3 feet with June flowers.
Miscanthus purpurascens (Flame grass) A nice sized Miscanthus to include in the middle of garden beds with softer foliage than Miscanthus sinensis. Great yellow-orange fall color makes this grass look like it's on fire (hence the name). One of the earliest blooming Miscanthus with late July/August with coppery flowers. Grows to about 4 feet with flower.
Miscanthus sinensis 'Autumn Light' (Autumn Light Japanese silver grass) An elegant and very cold-hardy Miscanthus with a regal, vase shape and narrow, dark green leaves. Very similar to 'Gracillimus', but not rounded and earlier blooming. Flowers emerge in September with a red/bronze cast, maturing to silver. Withstands even heavy snowfall. Tall, to 7 feet in flower.
Miscanthus sinensis 'Gracillimus' (Maiden grass) Thin, silver-veined, very narrow leaves and a more rounded shape have made 'Gracillimus' one of the best loved Miscanthus. Blooms emerge red in early October. Fairly fast growing in full sun and is drought tolerant once established. To 6 feet.
Miscanthus sinensis 'Malepartus' (Malepartus Japanese silver grass) One of the earliest to emerge in the spring. Malepartus flowers are a brilliant reddish purple when they emerge, slowing fading to silver. Lovely movement in the wind. Erect growth habit and good fall color. One of the first Miscanthus to flower in August. STANDS TALL AND STRONG IN WINTER. Grows to 7+ feet.
Miscanthus sinensis 'Morning Light' (Variegated maiden grass) Narrow, white-variegated leaves and a lovely arching form make 'Morning Light' a favorite Miscanthus for the garden. Particularly pretty when backlit, or alternatively, when set against a darker background. Refined and elegant, 'Morning Light' can also tolerate some shade (but it will be smaller and may not bloom). Try it in a "White" garden. Manageable size with flowers to 6 feet in September (shorter in part shade). Elegant.
Miscanthus sinensis 'Sarabande'
Similar to Gracillimus with its narrow leaves and rounded structure, but a bit shorter at 5-6 feet. Sarabande also blooms earlier and seems hardier here in southern Maine. Blonde seed heads emerge in August, turning to silver.
Miscanthus sinensis 'Strictus' (Porcupine grass) Attractive, yellow bands and spiky foliage are the trademarks of 'Strictus'. Unlike Zebra Grass, 'Strictus' does not flop. Great when used as a specimen plant. Red flowers emerge in September, turning more wheat colored as the temperatures drop. Can take moist environments with full sun. 6 feet with flower.
Molinia caerulea 'Skyracer' (Tall purple moor grass) Molinia starts out as an unassuming mound of soft green grass in the spring, but becomes an interesting presence in mid-summer when its airy seed heads begin racing to the sky. Stunning golden fall color and vase shape. Can be used as a specimen or looks great when planted in small groups. Full sun, dry conditions. Foliage to 3 feet, flowers to 6.
Panicum virgatum 'Heavy Metal' (Blue switchgrass) One of the oldest and best loved of the native Panicum cultivars, 'Heavy Metal' is reliably erect with good blue color. Easy to grow, 'Heavy Metal' looks great alone or when planted en masse. Needs full sun for optimal performance and has better than average drought tolerance. Pink-tinged blooms in July/August. Grows to 4 feet; 5 feet in flower.
Panicum virgatum 'Shenandoah' (Red switchgrass) 'Shenandoah' makes a good substitute for Japanese Blood Grass with bright red foliage emerging in mid-summer. Slower growing, but is tough, beautiful and drought tolerant. Great for sustainable landscapes and erosion control. Plant in 3s or more to make an impact. Grows to 3 feet; 4 feet with July flowers. Nice article on using Shenandoah in your garden: http://www.houzz.com/ideabooks/3998765/list/Great-Design-Plant---Shenandoah--Switchgrass
Pennisetum alopecuroides 'Hameln' (Dwarf fountain grass) One of the few Zone 5 Pennisetums, though we lost a lot of these after the winter of 2013/14 with tons of snow and a late late spring. Bold, elegant and classically shaped with lovely bottlebrush flowers. Beautiful, weeping green foliage turns to deep amber in winter. Won't reseed (unlike Moudry). Smaller size makes it ideal for garden beds. GOOD SALT TOLERANCE. Likes full sun and dry conditions. Flowers in July to 2.5 feet.
Pennisetum alopecuroides 'Red Head' (Red head fountain grass) Much bigger than Hameln with red-hued bottlebrush plumes that are 8-inches long. Arching, fine-textured foliage. Looks great in mass plantings. DRAMATIC AND SALT TOLERANT with massive blooms in August. This is a large fountain grass - to 4 feet in flower and just as wide.
Sorghastrum nutans 'Indian Steel' (Blue indian grass) With steely, blue foliage and tall flower spikes in late summer, 'Indian Steel' is great for modern designs. An American native grass, it is perfect for sustainable landscapes where it will tolerate neglect with grace. Needs lean, well-drained soil and will shrug off drought once established. Will lodge in wet soil. Prefers a protected location. 2 feet to 5 feet when it flowers in August/Sept. Design idea article: http://www.houzz.com/ideabooks/4368771/list/Great-Design-Plant--Indian-Grass