Contents Introduction Purpose of the Trial Judges Cultivation Notable Delphiniums Awards in 2007

The Royal Horticultural Society's Delphinium Trial is one of the long term Plant Trials at their Wisley Gardens. The delphinium trial is planted in the Trials Field adjacent to the Portsmouth road, which is approached by walking to the top of Battleston Hill from the main entrance to the Gardens. In June and July there is a spectacular view of the bed of delphiniums from the steps that lead down into the Trial Grounds.

Closer inspection reveals the wide range of colours and form available in delphiniums today.

The Trial includes several "Summerfield Delphiniums"

WHY HAVE A DELPHINIUM TRIAL?

The purpose of the Trial is to assess the suitability of delphinium cultivars for garden use. Plants that are judged to be of a sufficiently high standard are granted the prestigious "Award of Garden Merit" (AGM). Delphiniums that produce individual blooms of oustanding quality may be granted Awards that relate to their suitablility for exhibition. The collection of about 80 cultivars includes new introductions from delphinium breeders, older named cultivars that have not been fully assessed and some AGM delphiniums that provide standards for comparison. The plants are mostly cultivars of "delphinium elatum" type of UK origin, with a few cultivars of "belladonna" type.

WHO JUDGES THE TRIAL?

Selection of the delphinium cultivars being grown and assessment of the plants in flower is the responsibility of the DELPHINIUM COMMITTEE. David Bassett is chairman of this Joint Committee, which currently has 11 members representing the Royal Horticultural Society and 7 members representing the Delphinium Society. The Committee meets both at the RHS Hall in London and at Wisley Gardens to

• select cultivars for inclusion in the trial, either by examining blooms of cultivars submitted to the RHS for consideration (3 blooms are required), or by discussion of the merits of cultivars known to panel members
• discuss general features of cultivation of the Trial and to recommend changes that might be beneficial
• inspect and assess the plants in flower. A cultivar must first be judged to have reached the required standard in three years to be considered for the Award of Garden Merit.
• consider the recommendations for Garden Merit and Exhibition awards to be submitted to the Council of the RHS
• determine which cultivar is to be awarded the Stuart Ogg Medal for the best display in the Trial.

TRIALS REPORT

The RHS Delphinium Trials and Awards are described in Bulletin Number 5, June 2004: "Delphiniums" prepared by Wendy Wesley and Dr David Bassett. Copies of this Bulletin can be obtained from the RHS by writing (enclosing £2 in postage stamps to contribute to costs) to:

Trials Office, RHS Garden, Wisley, Woking, Surrey, GU23 6QB, UK

or via the RHS website www.rhs.org.uk/trials

The RHS website includes many details of the Trials and Awards

AWARDS IN 2007

After inspections of the Trials by the Committee during June 2007, the Award of Garden Merit was given to Delphiniums:

• 'Elisabeth Sahin', raised by Duncan MacGlashan, which has white flowers with a white eye
• 'Kennington Classic', raised by the late TN Murphy, which has creamy yellow flowers with a primrose yellow eye
• 'Holly Cookland Wilkins', raised by Henry Wilkins, which has pale violet flowers with a brown eye.

The Stuart Ogg Medal for the best display of flowers in the Trial was awarded to Delphinium 'Carol Fishenden' that looked beautifully fresh in late June when many others had been spoiled by heavy rain and strong winds.

CULTIVATION

Delphiniums are perennials but, at Wisley, a new Trial is planted each year. Cultivars are assessed in their second year of growth. All aspects of cultivation are carried out by the staff of Wisley Gardens.

The plants are raised from cuttings rooted under glass during January and February. Three plants of each cultivar are planted out in a newly-cultivated Trial bed in early May. These young plants grow quickly and are usually well established when the Trial for the current year is in flower during June/July. Most of the plants grow strong flowering stems later in summer. In the past, blooms were normally cut off in order to encourage further development of the base of the plant (crown) and the root system . During 2002 this procedure was changed and stems were allowed to develop and bloom. This results in a wonderful display of flowers with some of the blooms being of exhibition standard, making the Trial well worth a visit during August.

A consequence of the previous first-year treatment was that plants usually developed many (10 - 30+) flower stems in their second year. In gardens, such large plants would often be thinned by cutting out the weakest stems in the spring. This procedure is not followed for the Trial at the present time. The plants grow with many stems packed closely together, which is one factor causing the stems to grow far taller than in normal garden cultivation. Other factors favouring tall growth are high fertility of the soil, the close spacing of plants and the continuous irrigation used. The plants are protected against insect pests and fungal disease (especially mildew) by spraying with insecticide or fungicide when this is considered necessary.

A SELECTION OF CULTIVARS UNDER TRIAL

This selection includes named cultivars that have won awards or provided a spectacular display in recent years. It begins with two blue delphiniums.

'Pandora' is a relatively recent introduction from Blackmore and Langdon. It has consistently produced a spectacular display of long narrow blooms each year and was commended for garden merit in 1999, in 2002 when it produced a superb display, and again in 2003 to gain the Award of Garden Merit. This is definitely a delphinium for the back of a border as it is very tall.

The second blue, 'Kestrel', a light gentian with a black eye, has the distinction of being one of the earliest flowers in the Delphinium Trial. In 2002 it was in full bloom by 21st May, two to three weeks ahead of most cultivars and consequently was past its peak by the time of the first full meeting of the judging panel. It gave a superb display in 2006 and it has now gained the Award of Garden Merit.

The pure white delphinium 'Jill Curley' from D. McGlashan has performed well in the Trials and also gained the Award of Garden Merit in 2006. The plants produce many flower stems with broad, tapering blooms that are followed by a plentiful supply of laterals. This lovely white delphinium was already growing well in the garden at 'Cherry Barn' when we moved there and is a sturdy perennial.

'Lucia Sahin', also from D. McGlashan, gained awards quickly. The long, tapering blooms are ideal for exhibitors and this aspect was rewarded in 1996 with an Award of Merit for Exhibition. It also gained a first commendation for garden merit and the Stuart Ogg medal in 1996. A second commendation for garden merit was given in 1998 and it gained the Award of Garden Merit in 2001. This cultivar marked a breakthrough in the search for deeper colours in the dusky pink range and is retained in the Trial as a standard. The near claret colour of the fresh blooms fades very significantly as the blooms age. Lucia Sahin is not a prolific producer of the basal shoots required for cuttings but it is now more widely available as a result of micropropagation and can even be obtained from some Garden Centers.

These two cultivars in violet shades were grown first in the 1999 Trial.

Raised by R. Banks, 'Tiger Eye' is notable for the prominent gold beards on the black petals of the eye in the pale violet florets. This delphinium can produce large regular blooms suitable for exhibition. It received commendations for garden merit in both 1999 and 2000 for consistent displays of flowers but the Trial Committee has resevations about the susceptibility of this cultivar to mildew.

'Franjo Sahin' from D. McGlashan is notable for the strongly patterned colouring of the flowers with a pronounced deep violet picotee edge overlaying the rosy-purplish colour of the sepals. This cultivar was awarded a commendation for garden merit in 1999 and the plants have produced good displays of long regular blooms. There are some reservations concerning a possible tendency for the flowers of this cultivar to drop rather quickly.

Creamy-white delphiniums always look particularly yellow at Wisley and the cultivar 'Kennington Classic', raised by the late Terry Murphy and introduced by Committee member Ray Joslyn was excellent in 2006, gaining a commendation for garden merit. The flowers are of beautiful form and regularly arranged in the spike. The Stuart Ogg Medal for the Best Display in the 2006 Trial was awarded to this delphinium.

'Carol Fishenden', another delphinium raised by the late Terry Murphy, is a new introduction to the Trial. It has light blue flowers that have been successful on the Showbench and it will be interesting to see how suitable it is for garden use. In the 2006 Trial only one plant flowered well and the blooms were very tall and quite loosely packed.

'Shottesbrooke Lady' is a another recent entry in the Trial. Raised by Roy Redman, it is late flowering and in 2006 was at its best on 10th July, when most other plants in the Trial had finished with their flowers spoiled by hot weather and thunderstorms. The colour is a pale pink set off by a brown eye and the blooms are of lovely form. There were many blooms of true exhibition quality on the three plants and the judging panel recommended a Preliminary Commendation for Exhibition, as well making the first commendation towards the AGM.

The cultivar 'Volkerfreiden' is of belladonna type with 'single' (5-petalled) flowers and a branching growth habit. Most often seen as a cut-flower in florists shops, 'Volkerfrieden' has done well in the Trial and gained the Award of Garden Merit in 2003. Plants are widely available in commerce and this delphinium has the advantage of giving an excellent second flush of flowers in late summer if cut down in July.

'Susan Edmunds' gained entry to the trial via the 'classic' route when the raiser submitted blooms to the RHS for consideration by the Joint Delphinium Committee. This delphinium originated as a self-sown seedling in the garden of Mr Edmunds, who recognised that the large, fully-double florets are unusual and took cuttings to increase his stock. The plant has grown very well at Wisley and after some uncertainty relating to variability of the flower form it has now gained the Award of Garden Merit. The blooms should be of interest for both garden display and flower arrangements.

The final cultivar in this selection, 'Sarita', raised by Terry Dowdeswell in New Zealand, also has fully double flowers. The blooms are elegantly long and tapering but, as for 'Susan Edmunds', there seems to be some variability of the form of the inner sepals/petals in the florets. The fine display of attractive flowers of 'Sarita' in its first appearance in the Trial in 2006 was rewarded with a first commendation for Garden Merit.