Mary Hockenberry Meyer, Extension Horticulturist Gail Hudson, Extension Communication Specialist Volunteers and Minnesota Landscape Arboretum Gardener Erik Lemke used a gas powered trimmer, rakes, and tarp to move switchgrass tops to the compost pile on May 9, 2018. The other grasses were burned May 2nd before new growth started. Photo: Mary Hockenberry Meyer Perennial ornamental grasses, once established, can be one of the easiest plants to grow in your garden. And spring time may be the only time when you'll need to give them a bit of attention. Take a good look at your plant. Is the center of it dead? Large mature grasses with a dead center can particularly benefit if they're divided in the spring.