John Warner seems to have died about 1721 or 1722, and his widow then purchased Harts, an estate at Woodford, Essex, which, on her death in 1743, she left to her son Richard.
Warner took Kalm to London, to Peter Collinson's garden at Peckham, to visit Philip Miller in Chelsea, and to see the aging Sir Hans Sloane.
John Ellis in a letter to Linnæus dated 21 July 1758, proposed should be called Warneria; Warner, however, objected, and it was named Gardenia.
Warner also translated several plays of Plautus into prose, and the Captives into verse, before the announcement of Bonnell Thornton's version.
Warner bequeathed the bulk of his property to Jervoise Clark, the widower of his niece Kitty, only child of his brother Robert.
A director of the East India Company in 1760, he left money to their hospital at Poplar, to David Garrick, and to fund for decayed actors.