Graceful Grasses

When we think about creating a beautiful garden, most often it is the flowers that we think about first.  But great gardens are much more than lots of pretty blossoms!

Contrast–the secret ingredient for designing a great garden

Great texture contests with Caradonna Salvia, Blue Oat Grass and Golden Princess spirea

Especially important is the way we incorporate different kinds of contrast into our gardens. 

This starts out with a ground plan that includes a thoughtful mix of sunny areas and shady areas,  as well as a compelling interplay of positive spaces (primarily the planted areas but also hardscape) versus negative spaces (primarily the lawn but also woodland or meadow areas). 

And we can also add delightful contrasts by selecting plants that introduce variations both in form and color, as well as complementary textures. 

Many favorite flowers have either a rounded form, such as the spherical blooms of peonies and hydrangeas, or flatter shapes like monarda, purple cone flowers and rudbeckia. And, almost instinctively, we combine flowers that have both contrasting shapes and colors. 

Consider the classic pairing of irises and peonies. This not only marries flowers with differing shapes, but also with contrasting colors. (And, most importantly, they also bloom together!)

But look a little further.  This particular pairing also combines two plants that have very different leaf textures, with the strongly-shaped peony leaves adjacent to the straight slender leaves of the irises. And, of course, the impact of their contrasting leaf textures is not limited to the few short weeks of bloom-time, but lasts all season long.

Fine textured grasses that dance in the win

Beyond herbaceous plants with inherently slender leaves, nothing beats the addition of some well-behaved garden grasses to add a delicate texture to our plant combinations. 

Furthermore, in addition to their fine linear textures, grasses also bring mesmerizing and graceful movement to our gardens.

Indeed, ornamental grasses, with their slender lines, soft colorations and elegant seedheads, have become a staple component  of contemporary garden design. 

Blue Oat Grass with Autumn Joy Sedum and the yellow hardy chrysanthemum called ‘Mary Stoker’

For season-long pleasure, think about pairing some lower growing Blue Oat Grass with the rounded fleshy leaves of robust sedums like Sedum’Autumn Joy’.  Meanwhile clumps of taller grasses are the perfect visual foil for colorful perennials like Daylilies, Purple Coneflowers, and Black-Eyed Susans.

And, if you wait until spring before cutting them back, most ornamental grasses will stand up well to wind and snow, adding greatly to the pleasures of our winter gardens. 

Clumpers versus runner

Most popular garden grass are clump forming, with each plant putting out small side shoots so that it gradually increases in the girth over time. In popular parlance they are known as  ‘clumpers’, but more properly designated as ‘tufted’ or ‘caespitose’.  

But beware of the ‘runners’. 

These thugs grow rapidly outwards via strong running roots—technically rhizomes or stolons—that soon spawn new plants far from the parent.   Running grasses like Spartina, which can be valuable for specialized situations such as bank stabilization, would be a disaster in a garden setting where their aggressive rhizomatous roots will quickly engulf all the neighboring plants

Cool season versus warm season grasses

Some of our best-known garden grasses make their strongest growth early in the season and then slow down in the heat of summer; thus they are known as cool season grasses.  

To protect the crown from the coldest temperatures I like to leave the tops standing over the winter. But, to avoid damaging the new growth, be gentle as you cut them back in early springtime.  I often merely loosen last years leaves by combing through the clump with my fingers; the new leaves will push through soon enough.

By contrast there are other grasses, known as warm season grasses, that wait until mid-summer to put out strong growth, meaning you must be a bit more patient to see them at their best.  

With the warm-season grasses you can cut them back more assertively in the springtime without being concerned that you might damage the new season’s growth. But again I avoid cutting too close to the crown—last year’s spent leaves will help protect it from late frost damage while still allowing the new growth to make its way through. 

Great grasses for northern gardens

Here is a collection of great garden grasses. And, as you peruse the offerings of various nurseries, you will surely find others to try. 

You may note two well-known grasses which I did NOT include in my list!  The first is  Maiden Silvergrass,  Miscanthus sinensis,—a  very popular warm-season grass which creates a substantial presence.  However in warmer places like Massachusetts it now self-seeds and is considered invasive, so I am choosing to avoid it. 

And I also left off Feather Reed Grass—Calamagrostis x acutflora ‘Karl Foerster’, which has not done well in my garden, probably because  it is now listed as Zone 5.

These then are my eight favorite grasses that all grow in my Goshen garden.

Blue Oat Grass adds a contrast of both color and texture in front of a Black Lace elderberry

Blue Oat Grass, Helictotrichon semervirens, with spiky leaves, and Blue Fescue, Festuca glauca,  which form delicate soft-textured cushions, are two low-growing cool-season grasses that will not overwhelm even the smallest garden.  Their attractive blue coloration contrasts beautifully among the rounded heads of Sedum ‘Autumn Joy’ as well as alongside the spiky and strong-colored flowers of purple Salvia (either the perennial or annual varieties). Unfortunately they may be somewhat short lived—about ten years in my experience.

Prairie Dropseed with the fall flowering bush clover

Prairie Dropseed, Sporobolus heterolepis, is another great choice for gardens of all sizes.  Over the years it becomes a low dense clump of slender leaves that turn a beautiful bronzy color as fall approaches, and their delicate haze of slender flowers appeal both to people and little birds.

The slender flower stems of Tussock grass start early in the season and their incredibly fine texture that adds a shimmer to garden from mid-summer to frost.

Tussock grass, Deschampsia cespitosa is a somewhat larger cool-season grass and also a personal favorite.  Over the years, my plants have gradually increased in girth to become  substantial mounds of slender leaves—now about three feet across—that create a season-long presence among my flowering perennials.  And I especially love the profusion of dainty stalks and filmy seed heads that shoot up from the center of the mound in midsummer, forming a diaphanous veil that floats among the nearby perennials.

Three warm season grasses, all of which hail from the prairies, also make great garden plants.  

The delicate stems of this larger cultivar ‘Standing Ovation’ of our native Bluestem grass makes a wonderful backdrop for the huge heads of Invincibelle Spirit hydrangea.

Most people know Little Bluestem (Schizachyrium scoparium), with its soft blue leaves. And I especially like the larger cultivars, ’Blue Heaven’  and ‘Standing Ovation’, as a beautiful contrast to the huge pinkish heads of smooth hydrangeas like Invincibelle Spirit.

Big Bluestem (Andropogon gerardii)—a less well known but a close relative—is a more substantial presence in my garden.  It also has bluish leaves that make a stunning backdrop to my fall asters.

Switch Grass (Panicum virgatum) is another prairie grass that works really well in a garden setting, with many interesting cultivars available. I especially like Shenandoah which has attractive bluish stems streaked with red. 

And finally, although far less common, be on the look-out for Tall Purple Moor grass, Molinia caerulea subs. arundinacea, another stunning warm-season grass.  It starts the season as a tidy mound of slender leaves. Then around mid-July a fountain of delicate flower stalks, over 6 feet high, shoot upwards, and look great when mixed among good-sized perennials like Heliopsis. And each fall I love to watch as small birds congregate to feast on its ripening seeds. For the best effect, plant it where it will be side-lit. 

Grasses for every garden

There are literally hundreds of kinds of garden grasses available, but many are for climates which are warmer than ours.   So, as you contemplate your choices, be sure to verify that they will be hardy where you live.

For my fellow Vermont gardeners–Look for Zone 5 if you live in the warmer parts of the Champlain Valley, otherwise restrict yourself to Zone 4 choices.  

Also be sure to check what you are buying is a ‘clumper’—beware of anything that might turn into a ‘runner’!

Blue Fescue, Blue Oat Grass, Prairie Dropseed and Little Bluestem are all perfectly sized for even the smallest garden, creating a wonderful contrast among pink and yellow flowers.   

But if you have a more expansive garden, consider including some taller growing grasses such as Switchgrass, Tussock grass and Purple Moor grass, all of which provide year-round interest.

And finally, the excellent reference  book by Rick Darke, ‘The Timber Press Guide to Ornamental Grasses’ is the perfect resource to guide you as you explore the wonderful world of great garden grasses.

 

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