The Derby City Council facility that used to supply the university fell victim to budget cuts a year ago, so it turned to the local firm for its cyclamen and poinsettia.
Managing director Mark Stone said: "I gather the council gets plants for bedding and baskets from a supplier in the north. The cuts are sad but I suspect Derby gets good value for money."
The council said the Markeaton Park greenhouse was not needed because it was cutting the number of flower beds by 40 per cent and could buy blooms elsewhere.
Percy Thrower worked at Markeaton Park and across the city during the 1930s and 1940s. His daughter Margaret told the local paper: "My father would be disappointed by the closure because gardening was his life."