Looking at the 1938 Dicksons catalogue, I notice that none of the rose names with 'Dicksons' in it have any punctuation. They don't call it Dickson's Centennial, which would only make sense if a Dickson personage was celebrating a 100th birthday, or even Dicksons' Centennial, which would more properly imply that the firm of Dicksons was now 100 years old.

'Dicksons Bouquet', 'Dicksons Delight', etc. are all lacking in apostrophes, as introduced by their raisers.