The RHS and Defra are offering Britain in Bloom groups another £50,000 to cover "the additional costs of using sustainable growing media and plants grown in sustainable growing media in order to protect the UK's valuable peatfields and support biodiversity and wildlife".
To apply, Britain in Bloom groups must be working with their local authorities.
Groups will need to work with local landscapers, growers and growing media suppliers to spend the cash.
RHS principal scientist Paul Alexander said of the Sustainable Horticulture in Partnership Scheme that he wants to create "an optimal balance between environmental benefit and horticultural enjoyment".
Apply at www.rhs.org.uk/britaininbloom by 23 May.