Sinclair had said its Wyevale contract was low margin and that Westland had shied away from the contract negotiations in the past.
Wyevale may also introduce an own label compost from Bord na Móna, which has a similar contract with B&Q.
Wyevale, Scotts, Bord na Mona and Westland said they would not comment.
Meanwhile, Terra Firma new vice chairman and head of portfolio Justin King visited Wyevale Garden Centres headquarters at Syon Park in London on 1 October on a fact-finding mission. Former Sainsbury chief executive King was shown round by senior staff as Wyevale plans to bring in a 150th centre to its estate.