Spiny Headed Mat Rush Lomandra longifolia Dalliance

Dalliance is a fine leaved selection of the spiny headed mat rush, arching into a soft rounded clump rather than the stiff upright fan of the raw species, so a mass planting reads as a green wave instead of a row of spikes. Underneath it is all root, a deep fibrous system that binds soil on a batter and holds through a bed that floods after a storm and then bakes for a fortnight. That is the work it is bought for: road batters, swale edges, carpark strips and slopes.

Batters, swales and carpark strips

Full sun to part shade and almost any soil that is not permanently waterlogged. It is a native of eastern Australia, takes frost, heat, drought, coastal wind and reflected heat off paving, and needs low water once established, though a drink through the first summer gets it away faster. For mass planting, space the clumps so they touch when mature, and leave a clear gap between the outer leaves and any path edge, because the leaf edges and tips are genuinely sharp and mat rush planted hard against a footpath catches ankles and shopping bags. It also suits a raised planter box in a courtyard, where the arching form softens hard edges and the roots handle reflected heat.

The failure mode is shearing it into balls. Hedge trimming a mat rush cuts every leaf at the same point, leaves a ring of blunt brown tips and builds a dead thatched core that never fills back in, and each trim after that makes it worse. If a planting has already gone woody and brown through the middle, cut whole clumps back hard and low, all of them at once, and let them reshoot clean.

Dalliance against the rushes and mat plants

Tassel cord rush is the strappy native to weigh it against, and the deciding factor is the site. The cord rush belongs on ground that stays damp, a pond edge or the low point of a swale, and it struggles in a dry exposed bed. Dalliance handles that same swale and also the dry top of the batter above it, which the cord rush will not. For a fine, low, shaded carpet rather than a knee high clump, green mondo is the alternative, though it will not take the exposure or do the erosion work. Cord rush is also the finer and softer looking of the two natives by a long way. See the mat rush range.

Cutting whole clumps back

Every few years, in late winter or early spring, cut the clumps down hard and low with a brushcutter or shears, taking the whole planting at once so it regrows evenly, then water and feed. In between, pull dead leaf out by hand and remove spent flower spikes if you would rather not have the seed. Feeding is optional, though a light application of low phosphorus native fertiliser after the hard cut speeds the flush back up. Wear long sleeves and gloves for any of this work, since the leaf edges cut skin easily.

Choosing a size

This plant is available in 2 sizes, from 140mm up to 200mm, priced from $19.95 to $29.95 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.