Additions to the specialist nursery's range include 'Celebration', which has mauve-blue double flowers on golden yellow leaves, and 'Sweetheart', described as a pink-coloured herbaceous scrambler that produces masses of strong flowers throughout the summer.
Other varieties being launched at Chelsea include Abilene (Evipo027), which comes from Raymond Evison and has pink blooms with contrasting yellow anthers.
'Little Mermaid' has light salmon-pink flowers with contrasting yellow anthers, while Summerdream 'Zosumdre' has mauve-pink blooms with a slightly deeper bar and veins.
As well as launching varieties at the show, nursery owners Jonathan and Ruth Gooch will be promoting their new book Clematis - an essential guide, set to be published on 6 May.
The highly-illustrated book includes information on all aspects of clematis, from selection to care, with more than 400 cultivars listed.