Tuesday, July 24, 2012

Designing with Ornamental Grass and some BFFs.

I have been enamored with Ornamental Grasses since I was exposed to them while working my first nursery job in California.  While they have always been an important part of our native plant palette, especially in the mid-western and prairie states, not until the last 30 years or so have they become an important part of the residential designer's plant palette.  Even today they are often not included in gardens for puzzling reasons.  The book first given to me regarding Ornamental grasses was The Encyclopedia of Ornamental Grasses, by one of the early american pioneers in grasses, John Greenlee. Another pioneer was Kurt Bluemel, whose website provides excellent information on a dizzying array of grasses and other plant material.

In the forward of the book, Wolfgang Oehme, who recently passed away wrote, "we were building on the knowledge of the late Karl Foerster (1874-1970), the famous horticulturist and author from Potsdam, Germany, who said, 'Grass is the hair of the earth.'  Foerster was a visionary who realized early the function of grasses in softening the garden and giving it a more natural look.  From the time they thrust their green spiky heads through the soil in the Spring, through dramatic summer and fall lushness and brownish, feathery maturity of winter, grasses make a distinctive statement each season.  As Foerster noted, 'How terrible a garden without grasses.'"

Wolfgang Oehme and James van Sweden formed one of today's most influential Landscape Architecture firms, Oehme van Sweden & Associates in 1977.  They pioneered a natural, low maintenance design aesthetic that has been labeled the 'New American Garden' style.  A quick pause to say that most of us do not have the multiple acre plots and huge dollars required to engage their services and install their beautiful designs, but the concepts and feelings evoked by their designs are accessible to all of us even in brief glimpses.

Piet Oudolf is a contemprorary dutch designer who has also spent much of his time designing with grasses in trying to attain a natural aesthetic.  Like Oehme van Sweden he draws inspiration from the natural world and in many designs will plant grasses and perennials in large drifts.  Take a look at these linked websites and I hope you can appreciate the beauty these visionaries have brought to the designed landscape.

Calamagrostis arundinacea 'Karl Foerster'
flower behind daylillies
Ornamental Grasses are an important part of these styles for their naturalistic look and ease of care.  Most grasses require only average soil, no fertilizer, minimal maintenance and if sighted properly (light, soil and moisture) do not suffer from any major diseases or insect infestations.  When you really spend some time with grasses you come to realize their beauty and diversity.  Some flower (set seed heads) early in the Spring, while others wait until late summer.  Some can be monstrous towering 10'+ beasts that dominate spaces, while others can be small, edge of the border clumps.  Some can have beautifully colored flowers (seed heads) that stand above the foliage and contrast with their green blades, while others have variegated and different colored foliage that contrasts with plants around them.  They all are unique and beg to find a spot in the landscape and border.

Three tips to consider when looking to add Ornamental Grasses to your garden.

First, never look at a grass in a one-gallon container and say that it is so cute and a perfect size.  Study any grass before you purchase so you understand its form and ultimate size. A one-gallon (12" tall) Miscanthus gracillimus will be 6' tall and 4' wide in a few years.

Pennisetum 'Little Bunny' flowers emerging
Second, the larger grasses can be used as individual specimens and provide excellent architectural structure year-round (mostly), but most grasses do well in groups, or drifts, as it will accentuate their movement and grace.  The 'New American Garden' style of Oehme van Sweden emphasizes more natural, larger drifts of perennials and grasses, reminiscent of the American prairie and not of the traditional English border.

Finally, grasses should be left standing in the fall and winter, for many of them provide wonderful interest in the winter and can be quite beautiful when covered with snow.  Some need a little support to stay upright all winter, but it is worth a little work, and come springtime most grasses are cut close to the ground in preparation for a new year.  Following are a few of my favorites.

Reed Grass with daylillies
Calamagrostis arundinacea 'Karl Foerster" (Feather Reed Grass) -  Hands down the best and my most favorite grass.  The plant leafs out early and sets bright green basal foliage about a foot high and right away in late-Spring it forms a big clump of seed heads that stand 3' over the foliage.  The flowers are purple that turn hay-colored as seen in this image and fade to brown in the fall.  With the tall seed heads it is one of the most dynamic grasses as it moves in the wind but does not fall over in heavy rain. It can be used in drifts and stand all by itself, or be in the back of the border and allow its seed heads to be part of the show.  To stand tall and be orderly it needs full sun and some moisture.  While grasses in general tolerate drought pretty well, this plant more than some others does need water.  It looks beautiful in Winter and holds up in the snow.

Blue Oat Grass in rock garden with daylillies and succulents
Helictotrichon sempervirens (Blue Oat Grass)  - In my opinion, this is the best and most reliable of the mounding blue grasses.  Unlike the Calamagrostis, this is a Mediterranean plant that likes dry sun and will rot if the soil does not drain well.  In New England it does well, but will suffer a little in the peak of summer humidity.  This grass forms a nice 2' round mound of spiky silver-blue foliage that does well in front of a border or in naturalized groupings.  Because of its broad form, it can get lost in a border if not given enough room.  It also flowers in the late-Spring with long drooping oat colored seed head, and I prefer to give this grass some room to strut its stuff.  While it is mostly evergreen in New England, it does not have the dramatic structure to provide much interest in Winter snow.  Come spring you do not cut this plant back, but run your hands through the foliage from the base out and pull out the dead blades.

Chasmanthium latifolium (Northern Sea Oats) - A somewhat different grass in that it does not have the typical blade of grass, but has leaves that come off a main stem, like bamboo.  It stands upright to 3' tall and forms nice clumps.  This is one of the few grasses that will perform in part shade, as it naturally occurs in woodland and stream settings.  Like the Feather-Reed Grass it likes some moisture.  It is stunning when formed in large groups around ponds and water and has a very lush green color in season in part shade.  It will turn a little coppery and yellow in full sun.  In summer the seed heads form in the shape of oat clusters and show very well as they turn oat-brown and contrast with the green foliage.  By fall the grass turns a coppery color and then to brown for Winter.  Another great plant with winter interest, again it might need a little support in the heavy snow.

Pennisetum "Little Bunny" and orientale (Fountain Grass) - As the name suggests, these are the grasses that emulate water coming up and out from a fountain. This genus has over 100 different species of grass in all sizes.   The grass blades tend to be soft and arching, and the flowers come in all colors from black, white, red and in between.  My favorite, "Little Bunny" is one of the smallest at about 1' tall. The Purple Fountain Grass is a favorite for containers though not a perennial in our zone.  The flowers come early in  summer and are true-show-stoppers.  Most plants are covered in soft, foxtail like seed heads that are persistent all season.  Because of their prolific flowering and soft stance in the wind, they are beautiful in groups and drifts as they are constantly in movement in the landscape.  While I like combining grasses with other complimentary formed plants (Iris, daylilly, coneflower), these can stand up by themselves.

Pink Pennisetum orientale flowers fading
While they are easy to care for, they are also easy to divide and provide more plants for your landscape or to give as gifts to others.  Generally you can dig up the plants when they are actively growing (Spring) and cut them into sections. If you take a big plant and break it into quarters, you will have some pretty substantial plants, the following year.  If you break it into eighths or more, it may take a season or two until you get a nice, full, flowering plant again.  With the big plants, like the aforementioned Miscanthus gracillimus, dig in the Spring, when not flowering, and use pitchforks, handsaws, reciprocating saws or chainsaws to cut into pieces.  Then with your hand-pruner clean-up dead roots and stems.  As you might infer, you don't need to be too delicate with grass.  If you want to form some drifts of plants, you can purchase several large plants and divide them immediately.  Five 5-gallon plants can yield you 20 plants easily.

One warning though, grasses can cause significant pain in the form of cuts if you run your hands and arms through them in the wrong direction.  If you are going to run your hands along the grass blades always go from the base to the tip, if you go the other direction you can cause serious pain with cuts and abrasions.  Like paper cuts sweat and dirt get in them and just make for a long day in the garden.  Just feel a grass before you work on or around it and save yourself some agony.

I hope this inspires you to spend some time and learn about grasses and see if you can find  space in your landscape to add some of these beauties.


  1. Reed, I confess to being one of those gardeners who has never included grasses in my designs. I am bookmarking this post so that I can come back to it, read it more carefully, follow the links, and educate myself. Thanks for the nudge. -Jean

  2. Grasses are just the best...I love them...and keep trying to find more spots for them in my garden! I agree about 'Karl Foerster', it is just so gorgeous, and it's so valuable to have a grass that gets growing so early in the spring.

  3. Ornamental grasses add view to gardens. You are absolutely doing well in that field. Keep it up.