Frequently overlooked and under-appreciated by most gardeners, ornamental grasses can add beautiful height, texture, and even fragrance. While it is true that the majority of ornamental grasses do best in full sun, a number will also tolerate shade as long as it is not too heavy and their other cultural needs are met.
Grasses for Part Sun
Among the useful grasses or grasslike plants are tufted hair grass (Deschampsia caespitosa), millet grass (Milium effusum), Hokonechloa macra ‘Albo-aurea’, variegated lily turf (Liriope muscari ‘Variegata’), and ribbon grass (Phalaris arundinacea var. picta). These vary from about 1 to 3 feet tall. Somewhat shorter are Virginia wild rye (Elymus virginicus), Alpine hair grass (Deschampsia alpina), and blue fescue (Festuca ovina glauca). And quite a bit taller are northern sea oats (Chasmanthium latifolium), creeping bluestem (Andropogon stolonifera), bluejoint (Calamagrostis canadensis), and bush grass (Calamagrostis epigejos), which may range from 2 to 6 feet tall.
One of the common complaints about grasses is the invasive nature of many of them. Anything with runners — ribbon grass (phalaris arundinacea), blue lyme grass (Leymus arenarius), and switch grass (Panicum virgatum) are the classic examples — is likely to be a problem. If you’re taken with something that comes without a description, tip it out of the pot and look for signs of runners (underground shoots with upward-pointing tips) before you take it home.
And almost anything with seeds will self-sow, that being what the seeds are for, though some, such as the fountain grasses (Pennisetum spp.), do it more aggressively than others. Be careful of plants described as self-sowing “manageably”; someone has got to do the managing, and that someone will be you. Nurseries are increasingly conscientious about labelling possible invaders, but it’s still best to check with your local extension service before you purchase and plant.
Several ornamental grasses give off appealing fragrance when their leaves are rubbed or broken. They include lemongrass (Cymbopogon citratus), citronella grass (Cymbopogon nardus), and sweetgrass or vanilla grass (Hierochloe odorata). When dried, sweet vernal grass (Anthoxanthum odoratum) is fragrant as well. Sweet flag (Acorus calamus) is a scented grasslike plant, but not a true member of the grass family.
Grasses for Cold Climates
Many of the most popular ornamental grasses are very hardy, including Miscanthus sinensis cultivars such as ‘Morning Light’ and ‘Purpurascens’; midsize favorites like the feather reed grass Calamagrostis arundinacea ‘Overdam’; yellow foxtail grass (Alopecurus pratensis), which seldom grows taller than a foot; and it’s even shorter cousin, A. alpinus ssp. glaucus, a 4-inch charmer with very blue leaves.
The Minnesota Landscape Arboretum conducted a large study of cold-hardy ornamental grasses and has published the results in North Central Regional Publication No. 573, “Ornamental Grasses for Cold Climates.” Call 952.443.1400 for information about how to obtain the booklet.