Short answer
For most ornamental grasses, the best thing to do in fall is very little. Leave them standing. The foliage and seed heads add texture and movement to the winter garden, protect the crown from the worst of the cold, and shelter birds and beneficial insects. Cutting back is usually done in late winter or early spring instead (see should all ornamental grasses be cut back in the spring?). For plants chosen for their autumn show, see ornamental grasses for fall color.
Fall checklist
- Leave the foliage standing, unless you have a reason to trim (see below).
- Water if the fall has been dry. If the ground has not frozen and rain has been scarce, a deep soak helps grasses go into winter well hydrated. This matters most for newer plants.
- Add mulch where useful. Newly planted grasses may benefit from a light mulch after the first hard freezes. A layer of shredded leaves around the base is a simple option. Avoid piling it against the crown.
- Skip the fertilizer. Feeding in fall pushes soft growth that cold can damage. See whether to fertilize ornamental grasses.
- Clean up the surroundings. Remove weeds and fallen debris from around the clump.
- Deal with tender and potted grasses. See below.
Should you cut now?
Most guidance recommends waiting. There are a few good reasons to cut in fall:
- You live in a wildfire-prone area, where dry grass near buildings is a hazard. Follow local fire guidance.
- The plant looks messy or collapses in winter, or sits next to a path you want tidy.
- You want to stop a self-seeding grass from dropping seed. (Choosing non-invasive ornamental grasses avoids this.)
If you do cut, bundle the stems with twine, cut to roughly 3 to 6 inches above ground with sharp shears, and compost the cuttings. The full method, plus guidance for warm-season, cool-season and evergreen types, is in our guide to cutting back ornamental grasses in spring or fall.
Evergreen grasses and sedges are not normally cut down at all, only combed or tidied.
Planting and dividing in fall
Early fall is a good time to plant or divide cool-season grasses, as long as there are roughly six to eight weeks before the first frost. Warm-season grasses are generally better planted and divided in spring. See how to plant ornamental grasses and how to divide and transplant ornamental grasses.
Tender and potted grasses
Tender grasses such as purple fountain grass will not survive a hard freeze in cold climates. Replace them each year, or lift and pot them and keep them somewhere bright and frost-free. Potted grasses of hardy types are best moved to a sheltered spot or sunk into the ground. See overwintering ornamental grasses in the ground and in pots.