Common Tussock Grass Poa labillardieri

Common tussock grass builds a soft fountain of fine folded leaves, grey-blue in most lines rather than green, and holds that shape without going stiff or spiky. In spring the flower stems rise well clear of the clump carrying open purplish heads that bleach to straw and catch low afternoon light. It is a grass of damp flats and creek margins through south-eastern Australia, and that origin explains how it is used: mass planted in bioretention basins, along swale edges, through native meadow beds and on batters for erosion control.

Ground that is wet in winter and dry by February

Full sun is where it belongs, and it is frost hardy across the southern states and the tablelands. The useful trait is its tolerance of ground that swings, saturated through winter and baked by late summer, which is exactly what a raingarden or a road-edge swale does to a plant. Soil can be clay, loam or improved fill, and drainage matters less to this grass than to almost anything else in the range. Water through the first summer to get the roots down, then leave it alone. Plant at roughly four to six per square metre so the clumps knit into a continuous drift and shade out weed seedlings in the gaps. The failure mode is thatch. Tussock grasses accumulate dead leaf inside the clump, and after a few seasons the middle goes hollow and grey while the outside keeps growing, so the planting looks tired and starts falling open. Cut the whole clump back hard in late winter every second or third year and it regrows dense from the base. Left uncut for five or six years it will not come back properly and needs replacing.

Poa or one of the other tussocks

Against knobby club rush the split is site. Ficinia is the coastal one, wiry and dark, built for sand and salt wind, where poa is softer, blue-grey and better through inland and southern gardens on ground that holds moisture in winter. For a fine texture in a garden bed rather than a civil planting, Little Pal mat rush is neater, keeps a tighter dome and can go longer between hard cut backs. Pick poa when you want movement and a meadow look and can live with a haircut every second or third winter. More options in lomandra and grasses.

Cutting back and keeping the clump lean

The one pruning job is that late winter cut, taken low across the whole clump with shears or a brushcutter before new growth moves. Every second or third year is enough, and annual cutting does no harm but is rarely needed. Remove the spent flower stems at the same time if self-seeding into adjoining beds is unwelcome. Feeding is a job to keep minimal. A light application of a low-phosphorus native fertiliser in early spring after cutting back will green a planting up, while richer feeding produces soft floppy growth that opens the clump out from the middle.

Choosing a size

This plant is available in 2 sizes, from 75mm up to 140mm, priced from $16.95 to $16.95 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. These are younger plants, priced for planting in quantity, and they establish quickly once in the ground. Not sure which to choose? Read our guide to low water gardens.