Not sure when to cut back or transplant your ornamental grasses?
Start by noticing when your plants send up blades of new growth in spring.
Early, cool-season grasses, such as blue fescue (Festuca glauca) and blue oat grass (Helictotrichon sempervirens), start growing in early spring and flower in late spring to early summer. Cut back the old growth by one-half to two-thirds of their height in late winter, before new leaves appear. Cool-season grasses take a rest in the summer heat, and then they may produce fresh growth in fall.
Plant or divide cool-season grasses in very early spring or late summer.
Warm-season grasses, such as maiden grass (Miscanthus sinensis) and switch grass (Panicum virgatum), are slow to emerge in spring. But they grow quickly when the weather warms up, reaching full height toward the end of the summer and then flowering and producing seedheads.
Plant or divide them in spring. Cut off their dead tops any time from mid-fall to mid-spring, making sure to do so before the new growth gets more than a few inches tall. That way, you won't damage the tips of young shoots.
Cut down small grasses with hand shears or garden scissors. For larger grasses, try handheld hedge shears, a power hedge trimmer or a chain saw.
Wear gloves, long pants and long sleeves when handling ornamental grasses to protect your skin from the leaves' sharp edges.
Check with your local university extension for more growing tips, or refer to The Perennial Care Manual: A Plant-by-Plant Guide: What to Do and When to Do It (Storey, 2009) for more tips on these lovely, workhorse perennials.