HLF launched a consultation in January on its proposed framework from 2013 to 2019 and is seeking views on how the grant distributor should spend its money. But an HLF representative said although some local authorities had responded it was "far from all".
The organisation said it would continue the Parks for People programme, which supports regeneration and conservation in parks, and was considering widening the range of projects to which it would award grants.
But head of landscape and natural heritage Drew Bennelick asserted that parks leaders must respond to the consultation to ensure parks were well represented. "Park managers and park departments must ensure that their councils are responding, and most importantly that parks feature in those responses," he said.
"Across local authorities there will be many people who will be contributing to the consultation, such as museums, leisure services, climate change advisers and archive staff and it would be all too easy for parks to be left out or forgotten," he warned.