Wyevale Garden Centres has four more acquisitions due to be announced this month, Horticulture Week understands.
Sidmouth is an award-winning £2.5m turnover garden centre in Devon. It won community involvement and commitment to customer service awards at the 2015 Garden Retail awards run by Horticulture Week.
The sales will take Terra Firma's Wyevale Garden Centres further towards its target of 200 centres, though Dobbies being no longer for sale means Wyevale is aiming at smaller centres to buy.
Wyevale Garden Centres was unwilling to comment.