Ornamental grasses are perennial plants valued for their texture, movement, and low-maintenance appeal in the landscape. Successfully moving an established clump to a new location, known as transplanting, requires careful attention to timing. Proper timing aligns the process with the plant’s natural growth cycle, minimizing shock and ensuring the rapid establishment of new roots in its new home.
Determining the Ideal Season for Transplanting
The general window for transplanting ornamental grasses falls into two distinct periods: early spring and early fall. Moving plants outside of these cooler, milder seasons subjects them to undue stress, often resulting in failure to establish. Early spring is widely regarded as the preferred time for most varieties, just as new growth begins to emerge from the crown.
Transplanting in spring allows the grass to dedicate the entire upcoming growing season to developing a robust root system. The plant can recover from the trauma of being moved before the stress of summer heat arrives and the cold dormancy of winter. This timing capitalizes on the natural surge of energy directed toward vegetative growth.
The second acceptable period for transplanting is the early fall, typically six to eight weeks before the first hard frost is expected in your region. This window is suitable because the intense heat of summer has subsided, and the soil remains warm enough to encourage root growth. Fall transplanting is less forgiving for the plant than spring transplanting.
If the root system does not fully establish before the ground freezes, the transplanted clump is susceptible to “heaving.” Heaving occurs when the freeze-thaw cycles of winter push the plant out of the soil, leaving the roots vulnerable to desiccation and cold damage. Therefore, spring timing offers a greater margin of safety for establishment than a late fall move.
Adjusting the Schedule for Different Grass Varieties
The precise timing within the spring or fall window depends entirely on the biological classification of the grass: whether it is a warm-season or a cool-season variety. These two categories have fundamentally different growth cycles tied to soil temperature. Ignoring this distinction is the most common reason transplanting efforts fail.
Warm-season grasses (WSCG), such as switchgrass, maiden grass, and fountain grass, thrive during the heat of summer and remain dormant until the soil warms significantly. These grasses must be transplanted in late spring or early summer, specifically when the soil temperature has risen consistently and active new growth is visible. Moving them too early, while the soil is still cold, keeps them dormant and delays root regeneration, making them susceptible to rot.
It is best to wait until the new green shoots are several inches tall, indicating the plant has broken dormancy and is actively channeling energy into growth. This late spring timing ensures the plant rapidly establishes its new root structure in the warm soil. Transplanting WSCG in the fall is discouraged in colder climates because the roots may not establish sufficiently before winter dormancy begins.
Conversely, cool-season grasses (CSCG), which include varieties like blue fescue and feather reed grass, begin their most vigorous growth cycle much earlier. They start growing in early spring and again in early fall, often slowing down or going semi-dormant during the high heat of mid-summer. Consequently, the ideal time to transplant CSCG is in very early spring, just as the ground thaws, or in early fall.
Early spring transplanting allows the plant to use the cool, moist conditions to establish its roots before the summer slowdown. An early fall move is also successful, provided it is timed well ahead of the first hard frost. Transplanting cool-season varieties during the peak summer heat, when their growth naturally slows, can lead to transplant shock and desiccation.
Critical Weather and Soil Conditions
Beyond the correct season, the immediate environmental conditions on the day of the move significantly impact the plant’s survival. A successful transplant relies on careful preparation and selection of a calm, mild day. The soil around the existing plant should be thoroughly watered a day or two before the move to hydrate the root ball and make the soil easier to work with.
Avoid transplanting during periods of extreme weather, such as high winds, which rapidly dry out the exposed roots and foliage, or intense heat spikes above 85°F. These conditions increase the rate of transpiration, stressing the plant when it is least equipped to handle water loss. An overcast or cloudy day is preferable, as the reduced solar intensity lowers the plant’s metabolic demands.
The best time of day to perform the transplant is either early morning or late afternoon, as the sun is less intense during these hours. Once the grass is in its new location, immediate and deep watering is necessary to settle the soil around the roots and eliminate air pockets. This process, often called “muddying in,” ensures the disturbed roots are in continuous contact with the soil moisture necessary for survival.