Relative newcomers to Canadian gardens, ornamental grasses have rapidly made up for lost time; so much so that it’s rare to find a herbaceous border without at least a few specimens. Many contribute as much oomph as petalled plants, while requiring much less care than most perennials.
Ornamental grasses include members of several different plant families: the true grasses (Poaceae), the sedges (Cyperaceae) and the rushes (Juncaceae). Although there are exceptions, grasses generally perform best with at least six hours of sunlight daily, while sedges and rushes prefer shade.
Most ornamental grasses grow best in average garden soil; very rich soil high in nutrients produces excessively lush growth, which can cause tall specimens to topple. If you need to improve its texture, add organic matter with low nutrient levels, such as shredded leaves or peat moss, before planting. Similarly, adding fertilizer (whether organic or chemical) to the soil can make otherwise well-mannered grasses invasive.
The majority of ornamental grasses are drought tolerant, making them popular choices for xeriscaping. Although newly planted specimens need to be irrigated while establishing strong roots, supplemental watering is usually unnecessary for older ones.
As with many perennials, grasses that have been growing in the same spot for several years may die out at the centre of the crown, producing a doughnut-like effect. When this happens, use a sharp spade to dig out the specimen by its roots; then, with the blade or a saw, divide the plant into quarters. Discard the dead sections and replant each quarter at the same depth. Water well.
While the foliage of ornamental grasses may be cut back to the crown in autumn, you can leave it in place for winter interest, then cut the dead stalks back to three to four centimetres above the crown in early spring before new shoots appear.