The event is set to attract leading Parliamentarians, industry figures and gardening celebrities.
The group, which seeks to foster greater understanding of the industry within parliament, was this year taken on a tour of Hampstead Heath by its management and conservation team from the City of London Corporation.
The group has also visited the Olympic Parklands. Forthcoming visits will include RHS Wisley.
Sponsors, subscribers and supporters of the group include Horticulture Week, the RHS, the HTA, the City of London Corporation, The Royal Parks and the Institute of Horticulture.
Scotts Miracle-Gro is acting as sponsor from the reception.