Watsonia borbonica subsp. ardernei is a (late) summer deciduous perennial growing flowers to heights varying between 50 cm and 2 m. The perennial plant part is its rootstock, a corm of up to 4 cm in diameter, often multiplying to form dense clumps. The robust stems may be purple.
The distribution of Watsonia borbonica in the far southwestern Cape ranges from the Cape Peninsula to Worcester and Bredasdorp, winter rainfall land that has dry summers. The habitat is mainly rocky sandstone slopes, but also granitic and clayey soils.
Prolific flowering happens in the first couple of seasons after fire. The plant, known on only a limited number of sites at present, is considered vulnerable in habitat early in the twenty first century (Bean and Johns, 2005; Manning, 2007; www.plantzafrica.com; www.redlist.sanbi.org).