Contents Introduction Purpose of the Trial Judges Cultivation Notable Delphiniums Awards

The Royal Horticultural Society's Delphinium Trial has for many years been 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" as AGM standards.

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 Elatum-Group cultivars of UK origin.

In 2007 / 2008 there was also an invited Trial of Perennial Delphiniums from Seed. The quality of the plants and their flowers was assessed for delphiniums from 46 entries, of which three Seed Selections were given AGM's.

During 2009, the whole programme of RHS Plant Trials has been reviewed. In future a Trial of Delphiniums will be held only if a proposal for a Trial from the RHS Delphinium Sub-Committee is considered of sufficient merit relative to proposals for Trials of other plants. An important consideration will be the number of new delphinium cultivars being introduced and available to the public through the horticultural trade.

The Trial of Delphiniums at Wisley in 2010 will be the last in the same format as Trials since 1993. However, the Delphinium Sub-Committee proposal for a new Trial for the period 2011 - 2013 was accepted and that Trial will be planted in 2010.

WHO JUDGES THE TRIAL?

Selection of the delphinium cultivars being grown and assessment of the plants in flower is the responsibility of the DELPHINIUM SUB-COMMITTEE. David Bassett is chairman of this Joint Committee, which currently has 10 members representing the Royal Horticultural Society and 7 members representing the Delphinium Society. The Committee meets 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

Recent recommendations by the Delphinium Sub-Committee have been:

• 'Foxhill Nina' AGM 2008, raised by L.T. Harrison, sent by L. Cooper, which has pale pink flowers with a white eye.
• 'Shottesbrooke Lady' AGM 2008, raised by C.R. Redman, which is late flowering and has light pink flowers with a brown eye.
• 'Carol Fishenden' AGM 2009, raised by the late T.N. Murphy, sent by J. Fishenden, which has light blue flowers with a black eye.

The AGM's for both 'Shottesbrooke Lady' and 'Carol Fishenden' will be confirmed only when these cultivars become available in commerce.

Perennial Delphiniums from Seed:

• 'Sweethearts' AGM 2008, sent by Jelitto Perennial Seeds, dusky pink flowers.
• 'Rosy Future' AGM 2008, sent by Mr Fothergill's Seeds Ltd., deep dusky pink flowers.
• 'Centurion Sky Blue' AGM 2008, sent by Sahin BV, Sky blue flowers with white eye.

For availability of these seed selections, see Topics 3.

The Stuart Ogg Medal 2009 for the best display of flowers in the Trial was awarded to Delphinium 'Ann Woodfield'. This pretty pale blue/lavender flower had lovely blooms on all three plants in mid June.

CULTIVATION

Delphiniums are perennials but at Wisley until 2009, a new Trial was planted each year. Cultivars are then assessed in their second year of growth. However, for the 2011 - 2013 Trial being planted during 2010, the plants will be treated as herbaceous perennials and remain in the ground for the period of the Trial. 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, as the picture taken on 11th August 2009 shows.

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 frequent 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.

The first blue, 'Kestrel' AGM 2006, a light gentian with a black eye, has the distinction of being one of the earliest flowers in the Delphinium Trial. In 2009 it was in bloom in May, two to three weeks ahead of most cultivars and consequently was past its peak by the time of the first visit of the judging panel to inspect the Trial on 9th June.

The second blue, 'Carol Fishenden', recommended for AGM 2009, also provides a fine display of light blue flowers with a black eye but in mid-season. The quality of the blooms is such that it has already become very popular with exhibitors and in 2009 was given a Preliminary Commendation (PC for exhibition).

The pure white delphinium 'Jill Curley' AGM 2006, from D. McGlashan has performed well in the Trials. 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' AGM 2001,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 the Stuart Ogg medal in 1996. 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.

Creamy-white delphiniums always look particularly yellow at Wisley and the cultivar 'Kennington Classic' AGM 2007, raised by the late Terry Murphy and sent by Committee member Ray Joslyn, has been excellent in the Trials. The flowers are of beautiful form and regularly arranged in the spike, so that the blooms are ideally suited for use by exhibitors as well as for garden decoration.The 2006 Stuart Ogg Medal for the Best Display in the Trial was awarded to this delphinium.

'Shottesbrooke Lady', recommended for AGM 2008, is a another relatively 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.

'Susan Edmunds' AGM 2006 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 was particularly good in 2009. The blooms should be of interest for both garden display and flower arrangements.

'Raymond Lister' was a new entry in the Delphinium Trial for 2009 and the display from the three plants was superb, gaining this cultivar a first commendation on the route to AGM. The plant was raised by amateur delphinium enthusiast, Joyce Bott, who named it in memory of Mr Lister who looked after Mr and Mrs Wainwright's famous delphinium garden, 'The Heath', at Adel near Leeds.

The 2009 Trial had several other new entries, including deep purple/blue 'Amadeus' and 'Titania', a light pink with white eye, both from the current Blackmore & Langdon Catalogue. Two new introductions of particular note were un-named seedlings, a violet flower GW1 from Yorkshire Grower, Gordon West, and a deep cranberry pink with white eye S9F from Sussex breedeer, John Flowerday. Both these seedlings impressed the Judges sufficiently for them to be awarded their first Commendations for garden merit in their first year in the Trial.

The performance of all these cultivars in the 2010 Trail will be watched with great interest as they should also be included in the 2011 -2013 Trial. We hope that some cultivars from Cherry Barn will also be new entrants in that Trial. It is essential that the delphiniums on Trial demonstrate recent developments in breeding, such as the extension of the colour range in dusky pink flowers that John Flowerday has been trying to achieve while reducing the tendency for colour fading.