In 1995, the BCS started a trial ground near St Albans which subsequently moved to Wisley, it most recently returned and shared space with that of the Royal National Rose Society. Unfortunately due to ongoing costs and availability of society members (plus other various reasons) the trials have now stopped.

The overall purpose of these trials was to judge cultivars for their value as garden plants, not as commercial or exhibition plants.

Clematis chosen for trialling were planted out at the trial grounds generally for a period of three years and are then judged anonymously by a panel drawn from the British Clematis Society. Clematis chosen as winners are awarded the Certificate of Merit.

In addition, from 1999 onwards, the best cultivar may be awarded, in perpetuity, the "Valarasan-Toomey Award", in the form of a silver medallion, which has been donated by Dr Mary Toomey, for many years the editor of the Society's journal The Clematis.

Since 2007 those plants which are awarded more than 80% of the vote recieve the BCS Certificate of Merit', while those that gain more than 70% receive a 'Commended Certificate'.

It should be noted that the years quoted were those of the award* and not the date that the plant trial started.

* The normal trial awards published for 2013 were made published in 2012, due to the trial site closing.

                 
Clematis 'Blue Eclipse' raised from a selected seedling of C.koreana by Sylvia Denny and the late Vince Denny in 1989 recieved the 'BCS Certificate of Merit'. The Single, (but very occasionally semi-double) blue, nodding, bell shaped flowers are produced on a plant to about 2.5 - 3.5m. The outside of the sepal is a deep-purple opening out to reveal silvery cream margins. A truly stunning cultivar that deserves to be in every garden. It demands a well drained position but thrives in poor soil like most of the koreana family.

                             
Clematis 'Kaiu' raised by Erich Pranno of Kaiu, Estonia in 1982 recieved the 'Commended Certificate'.This cultivar produces masses of nodding, pitcher-shaped flowers which are tinged pinkish-purple when they first come out, but this gives way to white as the flower matures. The flowers tend to open out slightly as it matures on a plant that once established can put on an immense amount of growth to about 2 - 3m.
Possibly the result of a cross between C.viorna and C.viticella subsp. campaniflora.

Clematis 'Emilia Plater' is a cultivar of the viticella group, which flowers from mid- to late-summer, with mid-blue/violet tepals that have a darker central bar and veining and creamy/green anthers.  It is a fully hardy, vigorous climber up to 10 feet that should be hard pruned in early spring (Group 3) and is an excellent, wilt-resistant garden plant.

Two cultivars were awarded a Certificate of Merit for 2001.
(Ref. Page 51 of 'The Clematis' BCS Spring Journal 2002)

Clematis 'Pink Ice' was raised by Malcolm Oviatt-Ham in 1995 from C integrifolia and C 'Royal Velours' at his wholesale nursery in Willingham, near Cambridge. C 'Pink Ice' is a non-clinging, Group 3 plant that can grow to 1.5m (5ft) through support. It has abundant, unusual, deep-pink blooms showing slightly twisted, well-separated tepals, and flowers from late June to September. Tests in the USA and Sweden suggest that 'Pink Ice' is frost hardy. In addition to the BCS Certificate of Merit, the cultivar was awarded the Valarasen-Toomey medal. As a recently bred cultivar, C 'Pink Ice' is not yet generally available.

Clematis montana 'Jacqui' was introduced in 1998 by Pennel's Nursery in South Hykeham near Lincoln. It was grown from a seedling found by Jacqui Williams when she was working at Priorswood Clematis in Hertfordshire.

A striking, vigorous and disease-resistant C. montana, 'Jacqui' can grow to over 6m (20ft) and is absolutely covered with pinkish buds that open to semi-double, pink-tinged, white flowers with yellow centres. This is an outstanding, Group 1, slightly-scented montana flowering from April to late June which is now widely available from specialist nurseries.

The year was not one that will be remembered with much pleasure by gardeners in Eastern England. Due to the vagaries of the weather the level of disease seemed to have been higher than we would normally have expected. Those of us that grow roses and clematis saw levels of mildew at an all time high. Any clematis that came through 1999 relatively unscathed is entitled to be called exceptional.

Only one cultivar was selected at the 1999 trials, described as "a confection of bright yellow open flowers and fresh green foliage with silvery seed-heads". This description refers to Clematis 'Kugotia' (Tangutica Group), Tradename: Clematis GOLDEN TIARA™. The judges were unaminous in their verdict. The plant had already received an Award of Merit and a First Class Certificate from the Royal Boskoop Horticultural Society in Holland.
(Ref. page 97 of 'The Clematis' BCS Journal 1999)