The news follows the decision by Dutch parent company Royal Van Zanten to centralise all breeding operations to the Netherlands.
Royal Van Zanten explained that the move would "enhance and optimise the company's successful chrysanthemum breeding programmes" and make its breeding operations more efficient and up to date.
A Cleangro statement said: "The Cleangro team would like to thank all our customers and colleagues for their loyal and valued support over many years."
The future supply of all UK Showmaker and Multiflora cutting orders will be administered and processed by Van Zanten Cuttings. For any enquiries, email firstname.lastname@example.org.