Iris Louisiana ‘Black Gamecock’

Louisiana Iris 'Black Gamecock' (Iris 'Black Gamecock') carries the darkest flower in the Louisiana group, a velvety purple deep enough to read as black in evening light. Clumps stand about 90cm tall and 60cm across on upright strappy foliage. Unlike bearded iris it wants moisture rather than sharp drainage, which makes it the answer to the damp corner nothing else will fill.

Why you'll love it

• A flower colour almost nothing else offers. Deep velvety purple on tall stems, striking against pale paving or a green backdrop.
• It thrives where drainage is poor. Boggy ground, pond margins and clay that stays damp all suit it, and wet feet are no problem.
• Frost hardy and heat tolerant at once. That rare combination lets one plant perform from subtropical gardens through to cool temperate ones.
• Bees and butterflies work it hard. The spring display pulls pollinators in, and the clump asks for very little in return.

Where it works best

Mass planting. Plant 40cm apart for a massed clump. At that spacing the foliage closes into a continuous sweep within two seasons and the flowers read as one block.

Pond and dam margins. It sits happily in permanently damp soil at a water's edge and tolerates shallow water over the rhizome through the growing season.

Borders and pots. The upright habit suits the back of a border or a wide container. Pots must stay moist, so choose a heavy one that does not dry out by lunchtime.

Growing Louisiana Iris in Australia

Position and climate. Full sun gives the heaviest flowering; part shade cuts the stem count noticeably. In cool temperate gardens the foliage thins back over winter and returns in spring, while in subtropical gardens it stays green year round.

Soil. Rich, moisture retentive and slightly acidic is ideal, and heavy clay is an advantage here rather than a problem. Set the rhizome just below the surface and mulch lightly, clear of the crown.

Water and feed. Do not let it dry out between spring and autumn, when both the flowers and next season's rhizomes are made. Feed a complete fertiliser in late winter and again once flowering finishes.

Dividing. Cut spent flower stems at the base. Lift and divide congested clumps every three to four years in late summer, replanting the vigorous outer pieces.

What to expect when it arrives

This iris is grown in 175mm pots and sold in packs of six, enough for a solid clump beside water or roughly two metres of border. Plants arrive as established fans of foliage rather than bare rhizomes, so they can go straight into the ground.

A few outer leaves may yellow in transit; trim them off and the plant will not miss them. Expect roots to hold within a month and the full display in the second spring. Delivered Australia wide, with delivery from $29.95. Every plant carries our 30 day healthy plant guarantee.

Plant care guides and related reading

• Best water plants for Australian garden ponds
• What to plant in a waterlogged garden
• Browse bee and butterfly attracting plants
• Compare other flowering perennials

Common questions

How far apart should I plant it?

40cm apart for a massed clump. Any closer and the rhizomes crowd each other within two seasons, which cuts flower numbers well before the planting looks full.

Can it grow in water?

At a margin, yes. It is happiest in permanently moist soil and will take shallow water over the rhizome while growing, though it should not sit deep all year.

Is it safe around pets?

No. Iris rhizomes are toxic to cats and dogs if chewed, so keep it away from a dog that digs, and wear gloves when you divide clumps.