During my summer break while in college, I would occasionally purchase and bring home an ornamental grass to grow on and to study. I would proudly display my purchase to my parents over dinner, since we often ate outside on the patio. One evening I brought home Switchgrass or Panicum virgatum. Although my dad was an avid gardener, he was also an engineer and preferred ‘orderly’ plants. He looked at my new purchase and simply stated it looked like a roadside weed and, to some degree, he was absolutely correct!
Panicum is a member of the grass family or Poaceae, and has over 450 species located throughout tropical and temperate grasslands nearly worldwide. Not surprising, the genus and species were penned by the Swedish botanist and physician Carl Linnaeus (1707-1778) in 1753 with the publication of his book Species Plantarum. The root of Panicum is from either the Latin panus, referring to an ear of millet or panis meaning bread. Panicum millaceium is the grain called millet, hence the connection of the genus with millet or bread. The species epithet is from the Latin Virg, meaning wand-like or twiggy and is a reference to the upright stems. The common name of Switchgrass is evidently a derivation of Quitchgrass (Elymus repens), which is a rapid spreading European grass.
Switchgrass is native from Nova Scotia west to Saskatchewan and south to Mexico and Florida. It is one of the main components of tall grass prairies and with a root system extending downward of 10’ or more, it contributed to the development of the deep topsoil layers of the Midwest. Interestingly, throughout its extensive native range, it has developed two distinct forms. In moister, lowland regions, the plants are genetically taller, reaching heights upwards of 8’ with broader leaf blades to nearly 1”. In higher elevations or more northerly locations, the plants reach a more diminutive 3-4’ tall, with finer and more delicate foliage, typically ⅜” wide! Similar to many other warm season grasses, such as crabgrass, Switchgrass has developed the C4 photosynthetic pathway, allowing it to be far more efficient during periods of drought and heat than the more conventional C3 pathway. Between its extensive root system and its modified photosynthetic pathway, Switchgrass will thrive in the worst of conditions. This explains why my dad thought it resembled a roadside weed, since it is often found growing in these harsh environments!
With such variations in height and texture, Switchgrass provides a tremendous wealth of diversity for selecting cultivars. One of my favorite forms is ‘Dallas Blues’. It was discovered as a seedling growing in a Dallas Texas garden by Ken and Linda Smith of Change of Scene Nursery in Ohio. This tall form offers beautiful powder puff blue foliage with a very attractive arching habit. The foliage grows to 5’ tall with a spread of 5-6’! In late August, large pink flower panicles, typically 10” long (as seen below), stretch well above the foliage and offer a frothy, pink glow to the autumn garden. Fall color is a brilliant gold and the plants remain upright and effective throughout the winter months. It looks great combined with Hydrangea paniculata ‘Limelight’, (seen above on the right) as the pink flowers of the Hydrangea nicely compliment those of the Switchgrass! If you are looking for even more height, consider ‘Cloud Nine’. Introduced by Bluemont Nursery of Maryland, this form also sports blue foliage with the flowers stretching upwards of 8’! ‘Cloud Nine’ can serve as a great screening or accent plant. The flowers are light tan in color, with the entire plant turning to light yellow with the advent of frost. As pictured on the right, ‘Northwind’ is another tall, blue foliaged form that has very distinct upright lance-like foliage. This form truly appreciates poorer soils and tends to collapse or ‘lodge’ if the soil is too fertile.
One of the assets of the upland, lower growing forms is the tendency for the foliage to display red highlights during late summer. The European, and in particular, the German nurseryman found these forms particularly interesting. ‘Haense Herms’ is a selection that starts the season with predominantly green foliage that gradually develops larger and larger amounts of red foliage as the season progresses. It has a rather relaxed habit and is easily woven together with various perennials. Come autumn, this selection sports bright red foliage. Dr. Hans Simon of Germany selected a seedling of ‘Haense Hermes’ which has more enhanced red highlights and a more upright habit. He named the seedling ‘Shenandoah’. Come autumn the foliage develops rich burgundy-red fall colorations. If the garden calls for a shorter blue foliaged form with upright foliage, consider ‘Heavy Metal’ (pictured below left). Selected by Kurt Bluemel, this form has a very upright habit and begins to bloom in early August. I have also seen it sport red foliar highlights come late summer, although it is not a dependable trait.
Switchgrass may appear along NJ roadsides but, it is far from being considered a weed. For foliage color, flower, form and a tough constitution that allows it to survive challenging sites, this is yet another must have plant for your garden!