Hothouse Flower by Lucinda Riley
Julia Forrester has many happy memories of a childhood spent at Wharton Park, playing amongst the exotic flowers her grandad cared for. Now, recovering from a family tragedy, she once more seeks comfort at Wharton Park, newly inherited by the charismatic Kit Crawford, with a sad story of his own. But when an old diary is found during renovation work, the pair turn to Julia's grandmother to hear the truth about the love affair that turned Wharton Park's fortunes sour.
So Julia is plunged back in time, to the world of Olivia and Harry Crawford, a young couple torn apart by the Second World War - and whose fragile marriage is destined to affect the happiness of generations to come, including Julia's own.