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Kniphofia---pick-of-the-pokers Flipbook PDF
Kniphofia---pick-of-the-pokers
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RHS trial
Pick of the pokers
Hot colours predominated at the RHS Kniphofia trial
Christopher Whitehouse details the species and best cultivars from the recent RHS Kniphofia trial
R
ed hot pokers are plants
that appear to come into – and go out of – fashion at regular intervals. One moment they are being lauded for their hot bright colours, the next condemned for short flowering seasons, untidy foliage and unimaginative use in the garden. Part of the problem is the lack of knowledge of the best cultivars and species of Kniphofia to use in a planting scheme. The first RHS Kniphofia trial was in 1927– 1929; three cultivars were trialled in 1960; the trial in 1971–1973 had to be abandoned after most became infected with violet root rot; and the
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last trial until now had been in 1981– 1983. Furthermore, the previous review of Kniphofia in cultivation (Taylor 1985) was over 25 years ago. The recent trial of Kniphofia by the RHS therefore provided a timely opportunity to re-examine those cultivars and species that have long been considered the best, and to compare them with the latest breeding highlights. The trial described here was conducted over three years from 2007 to 2009. This included one of the coldest winters in recent years, thus providing a good test of hardiness. There were 120 entries in
the trial, with three plants per entry. Unfortunately, some establishment problems resulted in a few wellknown cultivars not being effectively trialled as they died in the first year. These included ‘Alcazar’, ‘Erecta’ and ‘Little Maid’. The average height given below was measured as the first flowers opened on the spike. This is generally when the spikes look their best, although all pokers continue to extend in height as the flowers open up the spike. The flowering seasons given appear long, but the first flush is usually the most prolific. The plants then often continue to send up the occasional spike until the first frosts. September 2010
Plantsman The
1 Kniphofia baurii
Species
Christopher Whitehouse / RHS
The majority of plants in trial were cultivars, but it was important to include species for comparison. And many species make effective garden plants. However, the taxonomy of Kniphofia in the wild is fraught with difficulties. Codd’s (1968) coverage of the South African species is now 40 years out of date. Some tropical accounts have been revised more recently but the taxonomy is still open to debate. Molecular work has now confirmed the suspicion that most of the species in the wild hybridise with each other, blurring the boundaries. Only the most distinctive of species in cultivation can be named with any degree of certainty, and species should preferably be clonally propagated. Any seedlings from species in cultivation should be viewed with scepticism before assigning them to species. Nevertheless, several plants were submitted to trial as species as follows (the heights and seasons given apply to the plants submitted to trial, not the species in general):
A distinctive species, the rosettes form short woody stems and bear glaucous leaves. Within the species there is much variation, such as flowering time and leaf width. For the two named cultivars in trial, ‘Coral Breakers’ flowered almost two months earlier than ‘John May’, the latter had much broader leaves and formed less dense clumps. ‘Coral Breakers’: 70cm / June to August; ‘John May’ 100cm / September to October. Kniphofia citrina The plant grown under this name in the trial appeared almost identical to ‘Percy’s Pride’ – it had cylindrical flowerheads. The true species has small globose flowerheads with short ➤ flowers and exserted stamens.
2 Kniphofia breviflora
A small species to be grown for curiosity value rather than beauty, the flowers are a yellowish cream fading to a dark brown on dying.
Barry Phillips / RHS
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Wendy Wesley / RHS
September 2010
3 Kniphofia caulescens
Kniphofia brachystachya This species normally has very short, dull brownish flowers. The plant grown under this name in the trial turned out to be K. breviflora.
Ali Cundy / RHS
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The dark brownish bracts add to the rather subdued colouring. It was nevertheless an easy species to grow, which continued to throw up flowering spikes throughout the season. 50cm. May to November.
This species has dull red buds opening to greenish yellow flowers, and glaucous leaves. However, the true species is spring-flowering whereas the plant in cultivation is a late summer flowerer. This late form is regarded in the most recent South African flora as not belonging to K. baurii but as a form of K. lineari folia with greenish flowers and glaucous leaves. If it is not retained within K. baurii it would need a cultivar name to distinguish it from the numerous other variants of K. linearifolia. 80cm. August to October.
3 Kniphofia caulescens ‘John May’
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Tim Sandall
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Ali Cundy / RHS
Christopher Whitehouse / RHS
Christopher Whitehouse / RHS
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Christopher Whitehouse / RHS
Christopher Whitehouse / RHS
Christopher Whitehouse / RHS
Christopher Whitehouse / RHS
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Christopher Whitehouse / RHS
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Kniphofia ‘Atlanta’
Kniphofia thomsonii var. thomsonii ‘Stern’s Trip’
Plantsman The
Kniphofia ensifolia Two subspecies are recognised, one spring-flowering (subsp. ensifolia) and one autumn-flowering (subsp. autumnalis). The flower colour also varies for the subspecies but they are united by having glaucous foliage and exserted stamens. The plants in trial appeared to be mixed hybrids with no unifying characters. Genuine K. tuckii is now consider ed to belong to this species but this name is confused in cultivation and plants grown under this name are possibly synonymous with ‘Atlanta’. Kniphofia foliosa A robust Ethiopian species, this has broad glossy green leaves which are barely keeled. It proved hardy, even in the winter of 2008–9, but as the foliage was cut to the ground by the frost and being spring flowering, it did not flower during the trial. 5 Kniphofia hirsuta
This is the only species with short hairs all over the leaf. It is one of the shortest, forming clumps of open rosettes; the flowers are a rather dull greenish red and yellow. It is often sold as ‘Traffic Lights’ but this does not seem to be distinct from the seed-raised strain of the species, which does appear to come true. There is another seed cultivar called ‘Fire Dance’ but it is not known how this is supposed to differ. 20cm. June to August. 6 Kniphofia linearifolia The archetypal red-hot poker forming large clumps of long messy leaves with big bold flowers in orange opening to yellow in late summer. This species and its close hybrids are the plants that give the genus its rather mixed reception. However, the species is variable and floriferous selections are worth having. 130cm. October to November.
September 2010
7 Kniphofia multiflora
Plant grown under this name turned out to be K. linearifolia, albeit a good form. True K. multiflora has tall narrow spikes of short orange buds opening to yellow which point slightly upwards on the stem. It is rather tender and generally requires protection under glass in the UK. 8 Kniphofia northiae With broad aloe-like leaves, this species has great merit as an architectural plant for the border. The flowerheads are rather coarse and with muted colours of pale red buds opening to cream, the flowers are not the most attractive part of the plant. The plants submitted to trial all had much narrower and more keeled leaves than is typical and hybridisation was suspected. On account of the broad-leaved forms of the plant, it retained its AGM. 9 Kniphofia pauciflora
A dainty species with bell-shaped bright yellow flowers edged white at the mouth. The flowers are also quite widely spaced and it looks most un-poker like. The species is highly endangered in the wild by urban development around its native habitat. 50cm. April to November. 10 Kniphofia rooperi
This is probably the most distinctive of the classic red-hot poker species. The plants are robust and produce large broadly globose flowerheads in bright red and yellow during September and October. They are one of the highlights of any border in autumn and it rightly retained its AGM. 110cm. August to October. 11 Kniphofia sarmentosa This is a winter-flowering species but, unless the winters are mild, the plants do not flower well. The spikes are elliptic and the colours rather
subdued. The leaves can be quite glaucous adding to its attraction when not flowering, but apart from its unusual flowering time it does not offer much to the gardener. 12 Kniphofia thomsonii
A strikingly different species, this has long, downwardly curved flowers widely spaced on the stem. There is a variety which has short hairs on the outside of the flower called var. snowdenii. The species is not reliably hardy and died in the cold winter of 2008–9. The plant of K. thomsonii var. thomsonii commonly found in cultivation and submitted to trial is almost certainly the same as that cultivated by Frederick Stern at Highdown, West Sussex. This clone has been shown to be a sterile triploid (Janaki Ammal 1950) that spreads by stolons. A full history of the plant was given by GrantDownton (1997). As there are more recent introductions of K. thomsonii it is helpful to distinguish this clone, so the cultivar name ‘Stern’s Trip’ is proposed here. It gained an AGM in the trial as a plant requiring some protection in winter. 100cm. June to November. Kniphofia triangularis A small grassy-leaved species, this is probably in the parentage of most of the fine-leaved cultivars. For a long time it was grown under the names K. galpinii, K. macowanii or K. nelsonii. The species has uniformly orange flowers in slender spikes that just overtop the leaves. It is not very hardy and susceptible to winter wet. The most common selection in cultivation is ‘Light of the World’. 80cm. August to September. Kniphofia uvaria The species in the wild is relatively small with rounded flowerheads ➤ 149
continued to be wrongly associated with the red-hot pokers of cultivat ion today, such as ‘Nobilis’. 110cm. August to November.
Cultivars Christopher Whitehouse / RHS
Kniphofia triangularis ‘Light of the World’
but there is great variation across its range. It was one of the original redhot pokers grown in European gardens, but was soon superseded by K. linearifolia and other more robust species. However, as K. uvaria and K. linearifolia were not differentiated until Codd’s 1968 monograph, the plants continued to be grown under the name K. uvaria. The name has
There were over 90 cultivars included in the trial, from historic heirlooms originating from the first attempts at breeding to some not yet available. On the whole, plants were entered to the trial correctly, but it is inevitable that the longer a plant has been around in cultivation the more confused the name becomes. This is especially prevalent in Kniphofia where, in addition to the common problem of mislabelling, new hybrid seedlings can easily grow up amongst the parent plants. If these seedlings are more vigorous than the parents they will eventually supplant the
original specimen. It is therefore important when maintaining old cultivars to deadhead the plants regularly and to divide them every few years to renew their vigour. The primary difficulty with deter mining the identity of old cultivars is the lack of good descriptions and images. Cultivars are often first offered by nurseries with little more than a description of their overall colour, height and flowering time, if you are lucky. Further description is usually confined to enticing the reader to buy their plants over other nurseries’ cultivars. This presented a real problem in trial when plants were evidently misnamed. For example, one particular clone was offered under four different names: ‘C.M. Prichard’, ‘Ernest Mitchell’, ‘H.E. Beale’ and ‘Star of Baden
Kniphofia ‘Bees’ Sunset’ and ‘Shining Sceptre’
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Kniphofia ‘Bees’ Sunset’
featured on the cover of the Journal of the Royal Horticultural Society some five years earlier. The plants in trial on this evidence should clearly be named ‘Bees’ Sunset’; so how has the confusion arisen? ‘Shining Sceptre’ was offered by Bressingham Gardens in their catalogue with the same description and
Christopher Whitehouse / RHS
One of the most outstanding plants in trial came in under two different but long-established names: ‘Bees’ Sunset’ and ‘Shining Sceptre’. It was important to determine which of these two names was the correct one to apply to the AGM plants in trial. ‘Bees’ Sunset’ was the last of the introductions from the Bees of Chester nursery, ranging from 1938 to 1960. It was originally described as ‘3.5ft, large heads of rich golden yellow streaked deep apricot, July to August’, a description which matches the plants in trial very well. Further confirmation is provided by this cultivar featuring on the front cover of the July issue of the Journal of the Royal Horticultural Society 1971. The bronzed stems show up clearly in this photograph. ‘Shining Sceptre’ was introduced by Alan Bloom of Bressingham Gardens. It was first offered in their autumn 1975 catalogue and described as ‘clear yellow, shading to primrose-ivory, on strong 100cm spikes, July to August’. A photograph of it appeared in the spring 1976 catalogue, which supports the description in the catalogue and is quite different in colour from the photograph
photograph until their March 1980 catalogue. A telling comment is then included in their entry for Kniphofia: ‘due to two very difficult growing seasons, we are sorry we can only offer the following varieties’. Only 5 entries were included that year compared to 14 the previous year and ‘Shining Sceptre’ was not among them. ‘Shining Sceptre’ did not reappear again in the Bressingham Gardens catalogue until spring 1987, when it gets prominently featured on the back cover as ‘A Bressingham introduction with dark green foliage and stout 100cm spikes of glowing golden orange’. There is a wonderful photograph of a mass planting of the plants as well and this time the photograph does match exactly the plants in trial and the photograph of ‘Bees’ Sunset’ from the RHS journal. It can only be surmised what happened in the intervening seven years as Bressingham Gardens attempted to restock this cultivar but clearly somewhere along the line the original ‘Shining Sceptre’ was lost and the magnificent ‘Bees’ Sunset’ was bulked up for mass sale under the wrong name. September 2010
Plantsman The
Ali Cundy / RHS
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Ali Cundy / RHS
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Wendy Wesley / RHS
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Baden’. The original descriptions of these plants are of little help, with statements such as ‘Largest of the yellow kniphofias’ being common. Although the descriptions often include a rough height and flowering time they are not sufficient to differentiate them. Modern cultivars will frequently have photographs accompanying the new plants or in the press releases, but the cost of photography prior to 1970s means that few older catalogues contain such helpful evidence. Sixteen cultivars received an AGM following the trial and are discussed here. It is interesting to note that of the 16 given the award, seven are from the last 10 years. This is an encouraging sign, indicating that current breeding in Kniphofia is not only alive and well but producing more floriferous, stronger and longer lasting plants. Some of the older cultivars, such as ‘Erecta’, ‘Royal Standard’ and ‘Samuel’s Sensation’, appeared to suffer from lack of vigour in the trial but still make great plants if they can be grown well. The raiser, where known, is listed first, followed by the introducer and date. 13 Kniphofia ‘Barton Fever’
14 Kniphofia ‘Coral Flame’
(Alan Bloom, I: Bressingham Gardens, 2010) This is a new cultivar awaiting introduction by Bressingham Gardens, subject to its performance in the trial. It performed wonderfully, with narrow leaves, compact height and abundant, striking, uniform coral-red flowers. It is a useful height for small gardens. 80cm. June–October. 15 Kniphofia ‘Fiery Fred’
(I: Bressingham Gardens, 1981) Alan Bloom obtained this plant from the rose breeder Jack Harkness and it is named for the Yorkshire cricketer and fast bowler, Fred Trueman. It is relatively tall with larg, well-shaped, elliptic, orange flowerheads. 120cm. June– November. 16 Kniphofia ‘Incandesce’
(Edmund Brown, I: Cotswold Garden Flowers, 2006) This is a fine, tall poker over good, neat foliage. The peachy orange flowerheads are unusual in that it is only the very lowest open flowers that change colour to pale apricot cream. 140cm. July–November.
(Lester Elliott, I: Cotswold Garden Flowers, 2000) Raised at the National Plant Collect ion of Kniphofia at Barton Manor, Isle of Wight, this is a cross between ‘Yellow Hammer’ and ‘Toffee Nosed’. It is an unusual selection with tidy cylindrical flowerheads of a soft burnt sienna fading to biscuit white. 100cm. August–September.
17 Kniphofia ‘Innocence’ (Alan Bloom, I: Bressingham Gardens, 1991) Another Bressingham introduction, this has a similar colour combination to ‘Barton Fever’ but with much narrower, cylindrical flowerheads. 110cm. June to November.
Kniphofia ‘Bees’ Sunset’ (I: Bees of Chester, 1960) This cultivar produced an amazing show of colour, being very floriferous with bronzy stems and apricot orange flowers. 90cm. June– October. See box (p150).
(I: Carlisle Nursery, 1992) Producing very long elliptic spikes (30cm) of a cherry red colour on medium tall plants, only the basal few flowers fade to pale yelloworange. The foliage is glaucous. ➤ 130cm. July–November.
18 Kniphofia ‘Jonathan’
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Barry Phillips / RHS
Katy Prentice / RHS
Barry Phillips / RHS
Ali Cundy / RHS
Christopher Whitehouse / RHS
Christopher Whitehouse / RHS
Ali Cundy / RHS
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(Jaime Blake, I: Bressingham Gardens, 2010) A new slender, elegant, poker, the small flowerheads of a clear, bright red are produced prolifically among the narrow foliage. It makes an ideal subject for smaller gardens. 100cm. July–November. 21 Kniphofia ‘Primrose Upward’ (I: Cotswold Garden Flowers, 2010) Originally submitted as ‘Maid of award of garden merit
Following the trial, these species and cultivars of Kniphofia have been proposed for the AGM: ‘Barton Fever’, ‘Bee’s Sunset’, ‘Coral Flame’, ‘Fiery Fred’, ‘Incandesce’, ‘Innocence’, ‘Jonathan’, ‘Moonstone’, K. northiae, ‘Penny Rockets’, ‘Primrose Upward’, ‘Rich Echoes’, K. rooperi, ‘Safranvogel’, ‘Sunningdale Yellow’, ‘Tawny King’, K. thomsonii var. thomsonii ‘Stern’s Trip’, ‘Timothy’, ‘Wrexham Buttercup’. September 2010
Orleans’ which is a different cultivar, this was renamed following the trial. It has yellow buds with a chestnut tinge opening to an attractive pale greenish yellow and it flowers over a long period. 100cm. May–November. 22 Kniphofia ‘Rich Echoes’ (Edmund Brown, I: Cotswold Garden Flowers, 2006) The compact oblong flowerheads are rich, warm, orange fading to yellow on dark bronzed stems. 110cm. June–November. 23 Kniphofia ‘Safranvogel’
(I: Gräfin von Zeppelin, c.1977) Of a delicate, soft, peach-pink, the elliptic- to diamond-shaped flowerheads are held well clear of the foliage. 70cm. June–November. 24 Kniphofia ‘Sunningdale
Yellow’ (Bryce-Wilson, I: Sunningdale Nurseries, 1968) The moderately sized spikes are a clear lemon-yellow and it flowers abundantly. 90cm. June–November. 25 Kniphofia ‘Tawny King’ (John May, I: Cotswold Garden Flowers, 1997) One of the best recent cultivars, this is instantly recognisable with
The Harry Smith Collection
20 Kniphofia ‘Penny Rockets’
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Barry Phillips / RHS
19 Kniphofia ‘Moonstone’ (Edmund Brown, I: Cotswold Garden Flowers, 2006) A fantastic recent introduction, this resembles a pale ‘Tawny King’ but the spikes are fuller and almost twice the length. 110cm. June–November.
Ali Cundy / RHS
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its elliptic flowerheads of brownish orange buds opening to creamy white on top of darkly bronzed stems. 100cm. June–October. 26 Kniphofia ‘Timothy’ (I: Carlile Nursery, 1976) This is a well-established favourite with unusual coral-coloured flowers, an elegant flowerhead and red stems. 110cm. June–November. 27 Kniphofia ‘Wrexham Buttercup’ (Watkin Samuel, I: Bakers of Codsall, 1946) With its large, golden yellow flower heads, this is one of the oldest cultivars with an AGM. However, its vigour decreased during the trial. 130cm. July–October.
Christopher Whitehouse is Principal Scientist (Botany) at RHS Garden Wisley References
Codd, J (1968) The South African species of Kniphofia. Bothalia 9(3&4) Grant-Downton, R (1997) Notes on Kniphofia thomsonii in cultivation and in the wild. The New Plantsman 4(3): 148–156 Janaki Ammal, EK (1950) A triploid Kniphofia. J. Roy. Hort. Soc. 75: 23–26 Taylor, J (1985) Kniphofia – a survey. The Plantsman 7(3): 129–160 153