The borough council has urged Rugby residents to check what waste goes into green recycling bins.
Green-fingered gardeners have been busy since the start of the hot spell, and as a result the amount of green waste being collected in the borough has increased.
But a number of bins have been found to contain quantities of soil and rubble, which means the waste cannot be sent for composting.
Coun Dr Mark Williams, portfolio holder for sustainable environment, said it was encouraging the amount of green waste being collected was increasing.
But he warned green bins could remain unemptied if found to contain soil, rubble or other debris not suitable for composting.
“This contamination prevents the contents being emptied into the green waste collection vehicle and then being sent for composting,” Coun Williams said.
“To help avoid additional disposal costs we would ask residents to only dispose of garden and food waste items in their green bins.”
For more information about what can be disposed of in green waste bins, visit www.rugby.gov.uk/recycling