Among the plant genera it is possible to grow in the UK garden, few are as unique and distinctive as Kniphofia.
Named after the German physician and botanist Johann Hieronymous Kniphof, Kniphofia have been cultivated in the UK for over 150 years. Kniphofia are well known as a staple of cottage gardens and herbaceous borders, where they are prized for their vibrant flowers. Kniphofia however are not without their critics, having long divided opinion among gardeners with their vibrant flowers, exotic form and oft-lamented ‘messy’ foliage.
Taxonomic placement and relatives
Belonging to the plant family Asphodelaceae, Kniphofia are most closely related to plants in the genera Aloe, Asphodeline, Asphodelus, Bulbine, Bulbinella, Eremurus, Gasteria and Haworthia – with all being classified into the subfamily Asphodeloideae.
While varying quite significantly, plants in this family broadly share a similar growth habit and inflorescence structure, with all growing as a rosette of leaves from a basal (often woody) crown and all producing tall raceme inflorescence on a tall leafless peduncle (sometimes called a scape). From a botanical perspective, the most unifying trait of plants in the Asphodelaceae are the relatively thick fleshy roots which contain chemicals known as anthraquinones, colouring them a vibrant yellow.
Geographical distribution and species
Kniphofia are most associated with South Africa, with 47 of the described 73 species being found there. The remaining species are typically endemic to neighbouring countries and regions including the Drakensberg mountain range, Ethiopian highlands, and southern Tanzania. Only a small proportion of Kniphofia species have reached the UK and even fewer have proven hardy.
UK hardy species include K. bruceae, K. caulescens, K. hirsuta, K. linearifolia, K. northiae, K. rooperi, K. tysonii, K. thomsonii and K. uvaria. A majority of these species originate from cooler and more mountainous regions such as the Eastern cape and Drakensberg where temperatures as low as -10°C are not uncommon.
Undoubtedly the first thing people think of when Kniphofia are mentioned are the vibrantly coloured flowers. While a majority of Kniphofia species share the quintessential remit of reds, oranges and yellows in their flower colour, among the species a range of different colours can be found including shades of salmon, coral, green, cream, white and even brown.
Kniphofia flower colour typically relates to the pollinators with which each species has co-evolved. Larger more classically coloured Kniphofia have adapted to attract pollination by hummingbirds. Conversely, species with smaller less vibrantly coloured flowers are typically pollinated by insects including flies, hoverflies and bees.
While flowers are undoubtedly the main event for Kniphofia in the garden, the foliage of some Kniphofia can also be an attractive addition to beds and borders. The leaves of “classic” Kniphofia are strongly keeled, with a tendency to bend under their own weight and sprawl in a sometimes messy and unruly fashion (particularly in larger species such as K. linearifolia and K. uvaria) – much to the chagrin of many a gardener.
The most attractive and unique foliage forms are typically found among the species. Undoubtedly the most spectacular foliage is held by K. northiae, which delights with its broad, curved leaves giving an exotic appearance more akin to an Aloe or Agave than a Kniphofia. Two other species notable for attractive foliage are K. caulescens, which demonstrates uniquely grey-blue glaucous foliage, and the more diminutive species K. triangularis which has a tidier grass-type foliage.
Breeding: crosses and cultivars
Owing to the relatively small remit of UK hardy species, Kniphofia have proven a fertile proving ground for plant breeders seeking to develop new cultivars that maximise and combine the benefits of hardy and non-hardy species. The first intentional cross of Kniphofia is recorded as having occurred in 1879, sparking early interest in Kniphofia breeding – particularly with the species K. linearifolia, K. pauciflora, K. triangularis and K. uvaria.
Early breeding efforts focussed on producing crosses of wild-collected species, giving rise to a range of what then were called new species but what we would today refer to as interspecific hybrids. Several of these early hybrids remain in cultivation including Kniphofia ‘Nobilis’ and Kniphofia x praecox – with the latter thought to be a cross of K. bruceae and K. uvaria.
The most prominent early Kniphofia breeder was Maximilian Leichtlin. Based in Germany, Leichtlin is reported to have begun Kniphofia breeding in the 1880s producing many early cultivars, several of which remain in cultivation today including Kniphofia ‘Star of Baden-Baden’.
The work of Leichtlin also inspired other plant breeders and nurseries, giving rise to a wealth of new cultivars in the early 20th Century including Kniphofia ‘Goldelse’ by Wallace & Co. of Colchester, a cultivar which itself went on to form the backbone of many further Kniphofia breeding programmes.
The results of much of these early breedings efforts however were lost in cultivation during the first and second World Wars, with land being converted instead to growing food. Collections of many species and a handful of pre-war Kniphofia cultivars however did survive and went on to form the foundations for post-war UK breeding programmes.
In the immediate post-war period, Bakers of Codsall and Bees of Chester were the most prominent nurseries producing Kniphofia cultivars, many of which remain in common cultivation today including K. ‘Bee’s Lemon’, K. ‘Samuel’s Sensation’, and K. ‘Wrexham Buttercup’.
In more recent years, Alan Bloom and Jamie Blake (both of Blooms of Bressingham), and Beth Chatto have become the primary UK breeders of Kniphofia cultivars, producing a wide array of popular cultivars – with breeding at both nurseries remaining active.
The most recent nursery taking on the mantle of Kniphofia breeding in the UK are Cotswold Garden Flowers, With Bob Brown and his son Ed Brown producing a wealth of new cultivars from the early 2000s onwards as well as introducing many Kniphofia cultivars bred by John May of Drummore.
While this history focuses primary on Kniphofia breeding from a UK perspective, in recent years there has been increasing interest in Kniphofia breeding in both the USA and Australia, producing a range of new cultivars in each respective country. Perhaps the most notable of these breeders are Janet N. Egger (of Terra Nova Nurseries, Oregon USA) and Richard G. Saul (of Itsaul plants, Georgia).
Breeding by both has focussed on producing ‘series’ rather than individual cultivars, with Egger producing the popular “Popsicle” and “Poco” series and Saul producing the “Glow” series. In recent years the “Pyromania” series, bred and released by the USA-based breeders Proven Winners, has also become increasingly commonplace in the UK.
Useful Kniphofia references
Whitehouse, C. (2016). Kniphofia the complete guide (RHS Horticultural Monograph). Chris Young (Ed.). The Royal Horticultural Society, RHS Media, Churchgate, New Road, Peterborough.
Whitehouse, C. (2010). Pick of the Pokers (RHS Trial Report). The Royal Horticultural Society.