Ornamental grasses can enhance a landscape with their soft colors, vertical lines, and gentle movement. While they are generally low-maintenance, it is essential to understand the proper techniques and timing for trimming ornamental grasses each year. Trimming most varieties during their dormant phase helps promote new growth and maintains their health and appearance. This guide provides insights on when to perform this task, the recommended tools, and the best practices to follow.
Warm-Season versus Cool-Season Grasses
Ornamental grasses are typically classified into two main groups. Cool-season grasses, such as fescue (Festuca spp.) and feather reed grass (Calamagrostis spp.), experience their peak growth during spring and fall when temperatures range from 60 to 75°F. Their growth slows down or halts during the hot summer months, only to resume as the temperatures drop in the fall. Depending on the climate, some cool-season grasses may retain their greenery throughout the winter.
On the other hand, warm-season grasses like switchgrass (Panicum spp.), fountaingrass (Pennisetum spp.), and muhly grass (Muhlenbergia spp.) thrive during the summer months when temperatures hover between 80 and 95°F. These grasses start growing in late spring or early summer and exhibit a change in color as they go dormant by late fall, offering visual interest to the garden during the winter.
When to Trim Ornamental Grasses
The ideal time to trim ornamental grasses is when they are dormant, which can be anytime from late fall to early spring. It is crucial to remove the old blades before the new growth emerges, as removing entangled old growth amidst fresh shoots can be challenging. The timing of the trimming can also impact the appearance of the grasses in your garden. While some prefer a neatly trimmed look in the winter landscape, others appreciate the colors, movement, and habitat value that grasses offer to winter gardens. Consider cutting back grasses on a mild day in late winter to maintain a tidy appearance before the spring rush in the garden.
Tools for Trimming
The choice of tools for trimming ornamental grasses depends on their size and the number of clumps in your garden. Pruning shears are suitable for small grasses, while larger ones may require a power hedge trimmer or a sharp pruning saw. Regardless of the tool, it is advisable to wear sturdy gloves, preferably leather ones, to protect your hands from any sharp grass blades. For substantial grass plantings, a power weed whacker with a blade attachment can simplify the task, and in extreme cases, a chainsaw may be necessary for very large clumps.
Steps to Trim Ornamental Grasses
Trimming ornamental grasses is a straightforward process that can be accomplished by following these steps:
Step
To begin the process of cutting ornamental grasses, first gather the necessary tools such as scissors, pruners, string, or painter’s tape. Tall grasses may require double binding, with several inches of space between each bind.
Next, proceed to Step 2: Cutting the Grass. It is important to consider the type of grass being trimmed, as cool-season grasses and warm-season grasses have different preferences. For warm-season grasses, trim them back to about 6 inches above the ground. Once all the stems have been cut and removed, trim the clump back a few more inches to create a neat mound. It is advised to shape the mound neatly after the majority of stems have been removed to ensure a clean appearance. On the other hand, cool-season grasses like feather grass should only be cut back to one-third of their full height to prevent damage.
After cutting the grass, proceed to Step 3: Cleaning Up. Gather the cut stems and place them in a wheelbarrow or on a tarp for disposal in a compost pile or yard waste bags. Use a rake to tidy up any stray stems and clean the area.
Moving on to Step 4: Clearing for New Growth. As the weather warms up, inspect the grass and remove any loose, dead debris, especially from the center where matting may occur. This action promotes better air circulation and provides unobstructed space for new growth to flourish.
In terms of caring for ornamental grasses throughout the seasons, it is essential to note that not all ornamental grasses are perennial. While many are perennial in suitable climates, some are treated as annuals in colder regions where they do not survive the winter season. Verify the hardiness zone of the grass to determine its winter survival in your area.
If grasses are cut back late and new shoots are inadvertently removed, it is generally not detrimental to the overall health of the grass. The plant will continue to produce new growth from its roots, compensating for any accidentally cut shoots.
Leaving old growth on the grass will not usually cause harm, but it can diminish the aesthetic appeal of the plant. The presence of dead foliage alongside new shoots creates an unattractive contrast. If a year of cutting back is missed, it is advisable to trim the grasses during the subsequent dormant season.
