The Royal Caledonian Society runs the competition, which was judged by officials including Jim Buttress, as well as having a People's Choice award, which is to be announced.
Dibley's is a former Chelsea plant of the year winner, and was in the running again this year.
Among Scottish, entries, Rumbling Bridge Nursery's owner Graeme Butler said: "It's the first time this hybrid of primula has been recorded. It happened on the nursery between two specimen primulas in the candleabra group. It's a lovely new thing, like having a dwarf candleabra - a stocky plant. There's a myriad of colours - dark red is the best."
Glendoick's Ben azaleas include Ben Lomond and Ben Lawers. Glendoick's Ken Cox launched a new edition of Scotland for Gardeners at the show, featuring 100 new Scottish gardens open to the public.
The HTA held a reception for 60 guests as the organisation, whose president this year, Stan Green, is a leading Scottish nurseryman, looks to show how it helps Scotland's horticulture ahead of September's independence vote.
The RHS had a similar presence, while there was much talk at the show of how independence could help Scotland promote its gardens, but might lead to business challenges in areas such as tax, postage and the EU.
See full report in HW next week.