Mondo Grass Ophiopogon planiscapus Nigrescens

Black mondo is a clumping perennial from Japan whose strap leaves emerge green and darken to a deep purple black, about as close to true black as garden foliage gets. Short spikes of pale lilac flowers sit low inside the clump in summer and are followed by glossy black berries. It is an accent plant rather than a groundcover, used in small drifts, as edging along a path of pale gravel, or in a shallow pot where the colour is close enough to register properly.

Soil and setting for black mondo

Give it soil improved with compost that still drains freely, and keep it out of ground that stays wet through winter. It grows well in temperate and cool gardens, holds colour through the cold months and takes frost. Setting matters more than soil here. Near black foliage vanishes against dark mulch, brown bark chip and charcoal pavers, while against pale gravel, sandstone, silver leaved plants or a light coloured pot it becomes the thing you look at. Plant it in tight groups rather than dotting single plants through a bed. It also works on its own in a shallow pot, where the crown can be kept out of winter wet and the foliage sits at a height you actually look at.

The failure mode is asking it to cover an area. It spreads by short runners and it is slow, so a large bed planted at wide spacing stays a grid of separate clumps for years with weeds in every gap between them. Buy fewer plants for a smaller, denser area and let it fill properly, or use green mondo for the broad work and keep the black for accent.

Black mondo as accent, not carpet

Green mondo and dwarf mondo are the coverage plants in this range, quicker to close over and supplied in strips and packs for large areas. Black mondo is the opposite kind of purchase, bought by the handful for effect. A useful combination is a green mondo carpet with black drifts read against it, provided the two are massed separately rather than mixed plant by plant. If the job is a hard wearing edge in an open sunny position rather than a shaded carpet, Dalliance mat rush is a tougher answer than any of the mondos. Black mondo is the accent within a scheme, never the field it sits in.

Dividing and tidying black mondo

There is no annual prune. Pull or snip individual leaves once they brown off, since shearing the whole clump leaves flat cut ends on every blade and they stay visible for months on a plant this dark. Feed in early spring with a general fertiliser and mulch lightly around the crowns rather than over them. Division is how you build numbers without buying more stock: lift a clump in spring, pull it apart into small fans with roots attached, replant immediately at close spacing and water in. The black berries can be left on the clump or snipped off with the spent flower stems.

Choosing a size

This plant is available in 3 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.