So, what’s the greenest trash bag? One made from biodegradable materials like potato or cornstarch, or one made from recycled plastic, which does not biodegrade? Go for the recycled one. While biodegradable trash bags may sound like the greenest choice, the reality is they don’t degrade when thrown away in landfills. Modern landfills are designed so no outside air or water can get in, so nothing inside will ever degrade, including biodegradable products. Recycled plastic is generally more durable than biodegradable bags, which prevents trash from accidentally ripping through the bag and flying all over the street.