The trick-or-treaters have gone. Halloween is over. The candles have been blown out. What happens to all those Jack-o'-lanterns now?

Campbell River residents are being encouraged to bring old pumpkins to the city's 12th annual Pumpkin Smash over the weekend.

The Comox Strathcona Waste Management Service is teaming up with the Campbell River Fire Department, dropping pumpkins onto the ground from an aerial ladder. For fun, yes. But also for the environment.

These smashed pumpkins will become compost rather than sent to landfill, where they don't break down as efficiently, and where they produce gas that is harmful to the environment.

According to organizer Elaine Jansen, garden educator with the Comox Strathcona Waste Management service, the Pumpkin Smash keeps thousands of kilograms of pumpkins out of landfills.

"We try to reduce anything going into the landfill. And [pumpkins] don't compost properly in a landfill," Jansen told All Points West host Robyn Burns.

According to Metro Vancouver Solid Waste Services, when food and other organic materials end up in landfills they create methane, the powerful greenhouse gas that can be damaging to the environment.

When pumpkins are in the landfill, buried under layers of waste and without access to oxygen, they cannot decompose properly. Organics also take up space in landfills. According to Metro Vancouver, over 30 per cent of what is sent to the landfill in the Vancouver region is compostable organics.

Vancouver's green bin system makes it easy for residents to avoid adding organics to landfills, says Sarah Evanetz, division manager of Metro's Solid Waste Services.

"Pumpkins can be composted with the rest of your food scraps," Evanetz told the CBC.

Evanetz said Metro Vancouver's disposal ban, which requires residents to separate food from regular garbage, has helped ease landfill concerns.

"There's been a great increase in the amount of composting across the region, and I'm sure that includes pumpkins after Halloween," said Evanetz.

Campbell River does not have a green bin system yet. But Jansen says residents can add their pumpkins to yard waste bags, along with leaves, to be collected as part of the city's yard waste drop-off program.

Evanetz cautions those who compost their pumpkins to make sure to remove items that can't be composted.

"Remove candles before composting because often they have those metal foils around them, and those cannot be composted," said Evanetz.