Fertilizing: Other than mixing in some compost when planting, and adding an annual 1 to 2 inch thick layer of compost each spring, ornamental grasses don't require extra fertilizer. If you're growing ornamental grasses on very poor soil, consider adding a small amount of an organic 5-5-5 fertilizer in spring.
Trimming & Pruning: The beauty of ornamental grasses is their fall flower heads that will last into spring. Leave the flower heads in winter to enjoy or cut a few to bring indoors and add to your flower arrangements.
When you cut back your grasses depends on if they are cool or warm-season grasses. Cool-season grasses such as fescue, ribbon grass, feather grass and northern sea oats should be cut back in early spring before new growth starts. Cut back the plant so about 1/3rd of the old growth remains.
Warm-season grasses, such as Japanese blood grass, maiden grass, and fountain grass, should be trimmed in fall if you don't want to save the grass heads, or mid spring before new growth starts. Cut these back to the ground. Use a hedge trimmer or hand pruners to cut back your grasses. Some, such as Miscanthus grass, have sharp grass blades, so wear gloves as well. Before cutting the grasses back, wrap a rope or Velcro tie around the bundle of grass and cut below the wrap. This makes it easier to gather the grass and move to the compost pile.
Mulching: Ornamental grasses benefit from a 2- to 3-inch layer of bark mulch added in spring. This will help maintain soil moisture and prevent weeds from getting established between the grasses.
Ornamental Grass: End of Season Care
Dividing & Transplanting: Ornamental grasses can get too large for an area and may need dividing every few years. This is also a good way to spread favorite ornamental grasses around your yard or share with friends and family. Also, some of the clumping types will die out in the center, indicating that they need to be divided.
To divide your cool-season ornamental grass, in spring before new growth starts and after cutting back the grass, dig up the clump. With a sharp spade or even a large serrated garden knife, cut the clump into sections. Replant in a similar area as the original grass, adding compost to the hole and water well. Divide warm season grass the same way from mid spring to early summer.
Pests & Disease: Ornamental grasses generally are low maintenance and pest free. However, young plants and new growth can sometimes have aphids and spider mites on the foliage. Sprays of insecticidal soap can kill them.
Diseases, such as rust and powdery mildew, can also effect ornamental grasses, especially in wetter areas. Space plants further apart and clean up the dead foliage well in winter or early spring to remove any fungal spores in the area.
While deer generally avoid most grasses, they still might show an interest, especially in ornamental grasses with young or more-tender leaves. Repellent sprays containing garlic, cayenne, rotten eggs or slaughterhouse waste, can be rotated and applied on the foliage to keep deer away. Of course, a 7-foot tall fence around your garden is the best defense.
Ornamental Grass: Extra Info
Ornamental grasses are not only low maintenance, attractive additions to your landscape, they are good wildlife plants providing feed and shelter for birds. They also are an ecologically good choice since they require little care and help prevent erosion.
To learn more about the plants we sell and how to grow them in your garden beds and patio containers, sign up for our inspiring emails.