Plant group
Eleven clumping plants for texture, movement and erosion control, with spacing for mass planting and the renewal cycle that keeps clumps alive.
Last reviewed 12 March 2027
Grasses and strappy-leaf plants are the lowest-maintenance group in this reference by a wide margin. Most need attention once every two or three years and nothing in between. They also do work no other group does: they move in wind, they hold soil on slopes with fibrous root systems, and they read as texture rather than as individual specimens.
Botanically these plants are not all grasses. Lomandra are mat-rushes, Dianella are flax-lilies, Ficinia and Carex are sedges and rushes, and Anigozanthos and Doryanthes are neither. They are grouped here because they behave alike in the garden: clumping or slowly spreading, strap-shaped foliage, no woody structure, and renewal by cutting back or division rather than by pruning.
That shared behaviour is what makes the group useful. A drift of clumping plants at a consistent spacing gives a bed a continuous base layer that does not need shaping, does not outgrow its position, and does not go bare at the bottom the way a shrub planting does.
The most useful distinction in this group is when a plant does its growing. Warm-season plants such as Themeda triandra grow through the hot months and go dormant, brown and dry-looking over winter. Cool-season plants such as Poa labillardierei do the opposite: they look their best through winter and spring and can look tired through a hot dry summer.
Neither is a fault, but it changes where each belongs. Kangaroo grass browning off in July is doing exactly what it should; planted along a front path where it is looked at every day in winter, it will read as dead. Put warm-season grasses where the summer view matters and cool-season grasses where the winter view does. In cool-zone gardens, weight the planting towards cool-season species so the bed has presence for more of the year.
This is where the group earns its place outright. Lomandra longifolia in particular has a deep fibrous root system that binds soil, which is why it appears on almost every road batter and drainage swale in the country. On a domestic slope it does the same job: planted at about 600 mm centres it knits within two seasons and holds the surface through heavy rain.
Ficinia nodosa suits the same role in coastal sand and in basins that fill briefly and drain. Carex appressa handles ground that stays wet. Between the three, most difficult drainage positions in an Australian garden have a workable answer, which is more than can be said for shrubs.
These plants look best in drifts of one species rather than mixed individually, because their value is textural and a single clump reads as an accident. Plant at roughly two-thirds of mature width — a metre-wide Lomandra at about 650 to 700 mm centres — so clumps just touch at maturity without competing.
Resist the urge to plant closer for quicker effect. Clumping plants that are crowded compete at the root, and the weaker ones die out unevenly rather than the whole drift filling in. A drift planted at correct spacing takes two seasons to close and then holds for a decade.
Mulch between plants at 50 mm and hand weed for the first two seasons. Once the drift closes there is very little for a weed to germinate into.
Almost every failure in this group comes from doing nothing for too long. Clumping plants accumulate dead foliage in the centre, which builds into a thatch, smothers the crown and eventually kills the middle of the plant. Once a clump has died out in the centre, it is very difficult to recover and usually needs replacing.
The two maintenance operations are simple. Cutting back means shearing the whole clump to between 150 and 250 mm in late winter, just before new growth starts. Lomandra, Poa, Themeda and Carex all respond well to this every second or third year. Dividing means lifting the clump, cutting it into sections with a spade, discarding the dead centre and replanting the vigorous outer pieces. Dianella and Anigozanthos need this every three to four years.
Anigozanthos is slightly different: remove spent flowering stems and old leaves at the base each autumn rather than shearing the whole plant, and divide when flowering starts to drop off. Doryanthes needs neither operation and should simply be left alone.
Several widely sold ornamental grasses are declared or environmental weeds in parts of Australia, and some spread readily from seed into bushland well beyond the garden. Before planting any ornamental grass not listed here, check its status in your state or region — this group is over-represented on weed lists, and a grass that seeds freely is very difficult to remove once it has established beyond the boundary.
Sizes below are mature height and clump width in open ground in average conditions.
Lomandra longifolia
The most adaptable strappy-leaf plant in the country, growing in every climate zone on this site, in sand or clay, in sun or part shade. Deep fibrous roots make it the standard choice for holding batters, swale edges and road verges. Cut clumps back to about 200 mm every third winter.
Zones: tropical, subtropical, arid, temperate, cool
Lomandra confertifolia
Finer-leaved and considerably smaller than the common mat-rush, which makes it the better option in narrow beds and courtyard plantings where the larger species would be too coarse. Forms a neat fountain shape. Tolerates dry shade under established trees better than most grasses.
Zones: subtropical, temperate, cool
Dianella caerulea
Clumping flax-lily with blue-green strappy foliage, small blue flowers in spring and glossy blue berries afterwards. The reliable choice for shaded mass planting under trees. Divide every three or four years, before the clump dies out in the centre and becomes difficult to recover.
Zones: tropical, subtropical, temperate
Dianella revoluta
Grey-blue foliage on a clump that spreads slowly by underground rhizome, making it useful where you want a drift to fill in over time. The more drought-hardy of the two common flax-lilies and reliably frost tolerant, which suits it to inland and cool-district plantings.
Zones: arid, temperate, cool
Poa labillardierei
Soft blue-green tussock that moves in the lightest wind, at home on cool damp ground and along creek lines. It is the natural choice for cool-zone gardens where a warm-season grass would look tired for half the year. Cut back to about 150 mm every second winter to renew the clump.
Zones: cool, temperate
Themeda triandra
Warm-season native grass with striking bronze seed heads through summer. It greens up with warmth and rain and browns off over winter, which is normal rather than a problem — plant it where that seasonal change reads as intended. Cut it back in late winter just before new growth starts.
Zones: tropical, subtropical, arid, temperate, cool
Austrostipa ramosissima
Tall arching grass that reads as a light screen rather than a clump, useful in the awkward situation where a shrub would be too solid and a tussock too short. Good in part shade under high canopy. Remove old flowering stems at the base each year rather than shearing the whole plant.
Zones: subtropical, temperate
Ficinia nodosa
Stiff dark green rush with a distinctive knobby seed head, tolerant of salt spray, coastal sand and basins that flood briefly after rain and then drain. It holds its shape without any attention for years. One of the few plants that genuinely suits the strip between a path and a beach.
Zones: subtropical, temperate, cool
Carex appressa
Vigorous sedge for permanently damp ground, pond margins and the corner of the garden that never dries out. Forms a large arching clump quickly. Cut it back hard in late winter; the old foliage builds up into a thatch that smothers the crown if it is left for several years.
Zones: cool, temperate, subtropical
Anigozanthos flavidus
The most robust kangaroo paw for open garden beds, considerably longer-lived and less demanding than the smaller hybrids. Tall flowering stems through spring and summer. Remove spent stems and old leaves at the base each autumn; leaving them is what causes the clump to decline.
Zones: temperate, subtropical
Doryanthes excelsa
Very large architectural rosette that becomes the focal point of whatever bed it is in, eventually throwing a tall flowering stem. Allow a full two metres of width and expect several years before the first flower. Slow, long-lived and effectively maintenance-free once established.
Zones: subtropical, temperate
Check that any grass or strappy-leaf plant you are considering is not a declared weed in your state or region. Check current biosecurity restrictions with your state or territory service before moving plants, divisions, seed or soil between states or regions. Some species have sharp or serrated leaf margins; wear gloves when cutting clumps back.