GrowingHQ

Ornamental grasses and sedges

6 plants — 5 true grasses and 1 sedge. They are shopped for together and cut back completely differently, which is what this page is for.

Cut the wrong one down and it does not come back

A deciduous grass is cut to about 10 cm in late winter and regrows entirely — it is the right and necessary thing to do. An evergreen grass or sedge treated the same way is disfigured for two or three years, and some do not recover at all: you comb the dead leaves out with your fingers instead. The foliage column below is therefore not a decorative note, it is the maintenance instruction.

A sedge is not a grass

Not pedantry — the two differ on average in what they want from the soil, and the stem section is the test that works in any season.

Grass and sedge stems comparedTwo stem cross-sections side by side. On the left, a grass stem: a circle with a hollow centre, drawn with a swollen node and leaves arranged in two ranks on opposite sides. On the right, a sedge stem: a solid triangle with no hollow centre, with leaves arranged in three ranks, one from each face. Beneath each, the practical consequence — a deciduous grass is cut to the ground in late winter and regrows; an evergreen sedge is combed through by hand and must not be cut down.Grass (Poaceae)hollowRound stem, hollow centreLeaves in 2 ranksUsually deciduousCut to 10 cm in late winter.It regrows completely.Sedge (Cyperaceae)Triangular stem, solidLeaves in 3 ranksUsually evergreenComb the dead leaves out.Shearing it disfigures it for years.
The stem section is the reliable test in any season. What follows from it is how the plant is cut back, which is where getting it wrong actually costs something.

Which of these gets cut down, and which does not

The single most useful division on this page, and the one no plant label carries.

Cut to the ground in late winter — 3

Deciduous. Leave them standing all winter — the dead growth is much of the reason to grow them and it shelters overwintering insects — then cut to about 10 cm in late February, before the new growth starts pushing through and makes the job impossible to do tidily.

Never shear — comb through by hand — 3

Evergreen and semi-evergreen. Pull the dead leaves out with gloved fingers in spring and cut nothing. These are also the ones doing real work in the garden in January.

Winter presence is not the same as evergreen

The distinction this catalogue keeps in separate fields, because collapsing them produces bad advice in both directions.

Miscanthus and calamagrostis are deciduous and are among the best things in the garden in January, because standing dead stems and seed heads catch frost and low light and hold their shape until spring. An autumn tidy-up removes all of it for the four months it matters most, and gains the gardener nothing — the plant looks better standing than cut. So “good in winter” and “evergreen” are recorded separately here, and a list built from the wrong one of them would tell you to cut down the plants you bought for exactly this.

Shade and dry soil

Grasses are associated with open sunny prairie planting, and several of the best ones here are not that at all.

Tolerates shade — 2

Hakonechloa is the one ornamental grass that genuinely wants shade rather than merely putting up with it, and the sedge is shade- and damp-tolerant — three things most ornamental grasses are not, and the reason a sedge is so often the right plant where a grass has been tried and failed.

Grasses for pots

One of the better uses for a grass — the shape reads properly when the plant is raised and lit from behind.

4 plants
PlantFoliageIn a container
Blue fescueFestuca glaucaEvergreenGood in a container long-term
Japanese forest grassHakonechloa macraDeciduousGood in a container long-term
Mexican feather grassNassella tenuissimaSemi-evergreenGood in a container long-term
SedgeCarex oshimensisEvergreenGood in a container long-term

Recorded wildlife value

The standing dead growth is the value here, which is why the tradeoff is an autumn tidy-up.

Every grass and sedge, compared

6 plants
PlantFoliageIn a container
Blue fescueFestuca glaucaEvergreenGood in a container long-term
Feather reed grassCalamagrostis × acutifloraDeciduousWorkable in a container, with conditions
Japanese forest grassHakonechloa macraDeciduousGood in a container long-term
Mexican feather grassNassella tenuissimaSemi-evergreenGood in a container long-term
MiscanthusMiscanthus sinensisDeciduousWorkable in a container, with conditions
SedgeCarex oshimensisEvergreenGood in a container long-term

Know the position rather than the plant? What can I grow? takes your light, soil, space and month and answers from this same catalogue — including which grasses it rules out for you and why.

Mexican feather grass seeds itself freely and is a recognised problem plant in some climates — its profile says where that matters and what to do about it.