Yellow Wild Iris Dietes bicolor (Moraea bicolor)

Yellow wild iris is the finer of the two Dietes commonly planted here, a lighter clump of narrow, pale green, strap shaped leaves that arch outwards rather than standing rigidly upright. The flowers are soft yellow with a dark maroon blotch at the base of each outer segment, held clear of the foliage in flushes through the warmer months, and a clump in full flush is covered in them. It is used for mass planting, for edging a driveway or path, and in coastal and low maintenance borders.

Where the finer clump works

It grows steadily, takes sand, clay and coastal exposure, and once established runs on very little water, which is why it turns up in medians and roadside beds. It tolerates frost, copes with humidity, and is not fussy about soil provided the site is not permanently waterlogged. In mass planting, space plants so the clumps just touch as they mature. In a border, allow room for the arching foliage or the front row will lean out over the edge and get walked on. It also holds up better than most strappy plants under the reflected heat of a driveway or a paved courtyard.

The mistake that costs people the display is cutting the flowering stems off when the blooms finish. Bicolor reflowers from those same stems, so removing them takes out the next round. Snap the spent seed capsules off if you want to stop it seeding into the garden, and leave the stem standing until it is brown and dry. Shearing the clump over like a hedge causes the same brown ended mess it does in any Dietes, so pull or cut old leaves individually at the base.

Bicolor or grandiflora

These two are sold as though interchangeable. Dietes grandiflora is taller and heavier, with broad dark green fans and larger white flowers marked violet and yellow. Bicolor is shorter, finer in the leaf and paler in the clump. Choose grandiflora when you need structure, cover at knee to waist height, or a plant that holds its own against a large building. Choose bicolor for narrow beds, softer texture, a longer warm season flush and any situation where the taller plant would look heavy. For a low woody shrub in the same neglected beds, Convolvulus cneorum is the contrast, though it will not last as long. The low maintenance range has more.

Renovating a tired clump

Every few years the centre of a clump goes woody, brown and tired, and the fix is a hard cut. After flowering, cut the whole plant back to just above the base, water it and feed it, and it comes back clean within a season. That tolerance for renovation is why it survives in commercial plantings where nothing else gets attention. Otherwise feed in early spring with a general fertiliser, divide congested clumps at the same time, and keep spent capsules picked off if seedlings are appearing in nearby beds. A new planting flowers better in its second year, so do not judge a young clump on its first season.

Choosing a size

This plant is available in 5 sizes, from 70mm up to 5L, 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.