The conference takes place on 28 November at the Flett Lecture Theatre at the Natural History Museum.
The theme is Citizen Science and Biological Recording in the Garden.
Coordinator Steve Head said: "The experience the forum has gained with projects in collaboration with OPAL and Gardening Which?, plus new initiatives to support citizen science, mean that we are keen to start enabling ordinary gardeners to help answer some of our remaining knowledge gaps. Gardeners will also be well placed to start monitoring changes in the UK's fauna and flora as climate change impacts become noticeable."
He added: "The conference will be important for planning the Forum's future. There will be an afternoon workshop in which you can make your recommendations for the next projects the Forum should develop. There will also be time for a general update and discussion about the Forum's progress and ambitions, and the launch of the first phase of the new website."
Speakers include Richard Bashford of RSPBand Kate Risely of BTO on Garden Birdwatch
and Francis Ratnieks of Sussex University on accuracy of the identification of flower visiting insects by volunteers, and the effects of different types of training.