Spiny Headed Mat Rush Lomandra longifolia

You have seen thousands of these without registering them: road batters, carpark swales, bioretention basins and every second commercial garden bed in the country. Lomandra longifolia is the straight species, a large coarse plant with stiff deep green strap leaves held in a broad upright fan, and leaf tips sharp enough to matter. Its distinctive quality is a deep fibrous root plate that binds soil on a slope, then survives being ignored, mown around, flooded and baked. Erosion control on difficult ground is what it is genuinely for.

Where the seedling species belongs

It grows across eastern and southern Australia, including Tasmania, and handles frost, extended drought, coastal exposure, clay and poor fill without complaint. Full sun and part shade both suit it, and it needs water only through the first summer. In mass planting on a slope, work at 800 millimetre to one metre centres, one to two plants per square metre, because these clumps get big and crowding them wastes stock. Spring brings dense cream flower spikes tucked down among the leaves, strongly scented in the morning, followed by seed that germinates readily in nearby gravel. The failure here is specification. This is seed grown, so no two plants are identical in size, leaf width or vigour, and it is a considerably larger plant than the named cultivars. Across a batter that variation reads as natural. In a formal row along a townhouse driveway it reads as a mistake, and within a few seasons it has swallowed the path edge and started catching people on the legs. Buy it for scale and roughness, not for a tidy line.

Species or selected form

If you want longifolia toughness in a plant that stays even, buy Verday, a selected form with narrower glossier leaf, a tidier clump and better tolerance of a wet basin, and the one to specify where a landscape architect will be inspecting the result. For anything low, fine and formal, Lime Tuff is the front row plant and this one is not. The straight species stays the right call for revegetation quantities, large scale batter work, bush regeneration and any site where the planting should look like it arrived on its own. It is also the one grown in the volumes those contracts call for, which the named selections are not.

The brushcutter cycle

Run a brushcutter or slasher over the whole planting every three or four years in late winter, cutting low, to clear accumulated dead leaf before new growth starts. Done at that timing it comes back clean within weeks and flowers the same spring. Doing it annually, or in the heat of summer, weakens the clumps and opens them up. Remove spent flower spikes on garden specimens if you want to limit self seeding into gravel and mulch. Feeding is optional on established plantings, though a slow release native fertiliser low in phosphorus in early spring helps a new mass planting close over sooner. More in mat rush.

Choosing a size

This plant is available in 4 sizes, from 125mm up to 200mm, priced from $16.95 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.