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Products > Dietes grandiflora
Dietes grandiflora - Fortnight Lily

[2nd Image]
Habit and Cultural Information
Category: Perennial
Family: Iridaceae (Irises)
Origin: South Africa (Africa)
Evergreen: Yes
Flower Color: White
Bloomtime: Spring/Summer
Synonyms: [D. vegeta, Hort.]
Height: 3-4 feet
Width: 2-3 feet
Exposure: Sun or Shade
Irrigation (H2O Info): Medium Water Needs
Winter Hardiness: 15-20 F
Dietes grandiflora (Fortnight Lily) - This evergreen rhizomatous perennial produces clumps of long, upright narrow leaves that reach 4 feet tall. The flowers rise above the foliage and have outer white petals with a golden area near the base and the inner petals are white flecked with brown at the base. The inner most petal like structures, called style branches, are violet colored. This species flowers year round in coastal southern California gardens with each individual flower lasting only a few days (up to 3) but quickly followed by new flowers. Flushes of flowers appear on roughly a two week cycle, which has given this plant its common name of fortnight lily. The fortnight lily is very drought tolerant in shade but can also be grown in full sun with regular to occasional irrigation, but seems to look and bloom best with regular watering. Unfortunately in areas that have such regular irrigation it also reseed prolifically and many consider it to be a thug in the garden, so really is best in drier situations where this is less of a problem. It is hardy to around 15 degrees F. It is a good container plant or can be used in mass plantings or as a solitary accent clump. Aside from the reseeding issue, the most common problem, especially it seems in commercial landscapes, is the way this plant is pruned as it is often sheared to removed tattered older foliage that good gardeners might take the time to cut away at the base. This plant comes from the Eastern Cape Region of South Africa. The name for the genus is from the Greek words 'di' meaning "twice" or "dual" and 'etes' meaning "affinities" because of this plants close relationship to the genus Moraea and the Iris of the Northern Hemisphere. The Dietes were once included with the Moraea, which grow from a corm, but were split off into their own genus because they are rhizomatous plants. Although this genus was described in the 19th century, these plants are often still mistakenly called Moraea. The specific epithet means large flowered. Dietes grandiflora has been long grown in the nursery trades as Dietes iridioides or Dietes vegeta, but this common large fortnight lily can be identified by examining the flower tepals and style arms; Dietes grandiflora has brown markings on the inner tepals and dark violet style arms while Dietes iridioides lacks markings on the inner tepals, with just the yellow spots on the outer tepals, and has pale violet style arms. As noted in "The Color Encyclopedia of Cape Bulbs" by John Manning, Peter Goldblatt and Dee Snijman (Timber Press, 2002) "the two species are often confused in the literature and the name Dietes vegeta has been misapplied to both plants in the past." We grow three variegated selection of this species, one with gray-green foliage with a cream named variegation called 'Variegata' , one that is slighter smaller with even grayer leaves and white variegation called 'Gray Ghost' and one with green leaves striped with yellow called 'Sunstripe' . We also grow a selection of Dietes iridioides that we call 'John's Runner The information on this page is based on research conducted in our nursery library and from online sources as well as from observations made of this plant as it grows in our nursery, in the nursery's garden and in other gardens that we have observed it in. We also will incorporate comments received from others and always appreciate getting feedback of any kind from those who have additional information, particularly if this information is contrary to what we have written or includes additional cultural tips that might aid others in growing Dietes grandiflora.