Can you compost pizza (or pizza boxes)?

  • Date: June 6, 2022

Everybody, it seems, loves pizza. In 2020, the pizza market in North America was over 48 billion U.S. dollars. However, pizza consumption brings with it a lot of waste – from leftover crusts to greasy pizza boxes. Is it destined for landfill – or can you compost pizza? Well, the answer isn’t overly straightforward. It depends largely on the topping – cheese and meat are best left out the compost bin in high quantities due to the pests they attract. However, the odd bit bit, buried deep should be okay. Lets take a closer look…

So, can you compost pizza?

Composting is a great way to dispose of organic waste in a way that benefits your garden and the planet. You will gain some nutrient-rich fertilizer – and you can divert waste from landfill. It’s a win-win. Pizza is biodegradable – it can be broken down by micro-organisms and its original components returned to nature. Everything biodegradable is not necessarily compostable but, luckily, pizza is!

Pizza crusts, which are essentially just bread, can be popped in the compost. Bread falls into the ‘greens’ category when it comes to composting – it is nitrogen-rich. The topping is the only part of the pizza that is debatable when it comes to composting. It is well-documented that dairy products and meat should not be added to the home composting pile. They are the most likely food scraps to attract pests and create a foul odor – not what we are aiming for. This makes composting pizza slightly awkward – lots of popular pizza toppings contain meat and/or cheese!

If you are just throwing a slice or two into the pile, this should not pose too much of a problem. Just ensure the pizza is buried deep in the center.  Most of the micro-organisms can be found in the middle of the pile and the dairy will be broken down as quickly as possible. In addition, it will also mask the smell from lurking pests looking for their next meal. Having a lid on the compost bin will also help keep pests away – they simply won’t be able to get to the food in there. However, as always, if you feel more comfortable you can just scrape the topping into the trash first and compost the base/crust.

Can you compost a pizza box?

Although there is some debate whether pizza boxes can be recycled (mostly they can!), the same controversy does not exist when it comes to composting pizza boxes. Pizza boxes make a wonderful addition to any compost pile. Being cardboard, they contribute to the ‘browns’ carbon-rich element of the pile. Although cardboard is not the most nutritious material out there, it plays an extremely important role in the compost pile. As well as adding carbon to maintain a suitable green: brown ratio, cardboard also helps keep the pile healthy by providing structure. The gaps that are created by cardboard and paper items allows air to flow. Without this, the breakdown of organic items can slow down or even come to a complete halt.

Some things to consider when composting pizza and pizza boxes…

When composting any item, it is good practice to break/cut it into smaller pieces. This allows the micro-organisms more surface area to work on and jumpstarts the process. It also allows nutrients to be distributed throughout the pile. If you are not able to do this, it is not strictly necessary – your pizza and its box will still break down, just a little bit more slowly.

It is also important to ensure that you are adding a suitable mixture of ‘greens’ and ‘browns’ to the pile. We recommend a 1:1 ratio – this is much easier to follow and avoids any complicated math. However, it is extremely important to look out for any changes in the pile such as pungent odor or dryness. Composting is not an exact science; no two piles are identical. It is very much trial-and-error. But that is all part of the fun! If you are new to composting check out some of the beginners FAQs answered here.

The bottom line

Pizza is as popular as ever – but it brings a lot of waste! Luckily, composting is an option for both the food waste and the box. Being predominantly bread, pizza can make a useful addition to the compost pile. It will help create a nutrient-rich fertilizer and divert waste from landfill.  The pizza itself provides some much-needed nitrogen to the pile whilst the box will add an injection of carbon – important elements needed to maintain a healthy pile.  Pests are the main concern if you add a slice with cheese or meat. You can either scrape this off into the trash or bury the pizza deep into the pile to mask the odors. Good luck!