What do you do with the contents of your paper shredder’s refuse bin? Conventional wisdom would say recycle it: It’s paper, after all. But, as it turns out, there is an even better way to use that mass of confetti that piles up when you feed documents through the shredder. Most shredded paper works very well as compost. Your home office has a wonderful, free, readily available composting material that you didn’t even realize you had.

What about the ink on that paper, you may ask? Much of it is harmless. There are a few specific types of documents you’ll want to avoid putting in the ground, but it’s easy to separate out the documents that need to go into the recycling bin from the ones that you can use to help grow tomatoes and roses in your backyard.

The key to composting shredded paper is that the pieces have to be pretty small. The long strips you see FBI agents piecing together on TV shows would not work well: You want something closer to confetti.

Cutting printer paper into smaller pieces creates more surface area, which in turn promotes faster composting. Paper—and, specifically, newspaper—is also high in carbon, which helps balance the nitrogen that comes from the discarded food and grass clippings that also make it into the compost pile, as highlighted in this 2013 overview from the University of Nebraska-Lincoln.

Luckily, most modern shredders will cut documents down to a compostable size. A basic cross-cut shredder will turn that same piece of paper into 200 pieces. Some more advanced micro-cut shredders, such as the Bonsen 12-Sheet Micro-Cut Paper Shredder, can turn it into about 2,000 pieces.

Most of the printed documents we usually shred can be used as compost, but there are a few exceptions, and it’s important to separate those out before adding paper to your compost heap. Avoid shredding glossy papers with lots of color on them, such as magazines, according to the Environmental Protection Agency (EPA). Color mailers, such as the postcard-sized ads you may receive from local politicians, are similarly safe to recycle but not for composting.

Newspapers are a bit of an edge case. Most modern newsprint relies on water- or soy-based ink. A small amount of it may leach into soil, but not enough to worry experts.

Finally, since many people use paper shredders to cut credit cards, it’s worth throwing in a friendly reminder that you should not compost shredded plastic. It will not break down quickly and may introduce microplastics into the soil.

Beyond these exceptions, most of the expert resources on this topic, including the San Francisco Environment Department, University of Maryland, and Tampa Bay’s Backyard Composting Program, are all aligned in recommending paper composting, so long as you dispose of these few exceptions separately (in your recycling bin).

Luckily for all of us, most of the documents that end up in shredders are printed on plain, non-glossy paper in black and white. Maybe this could be an opportunity for you to develop a green thumb as a backyard gardener extraordinaire, once you read up on the EPA’s guide to home composting. You’ll just have to get your hands a little black-ink stained first by shredding some junk mail to get you started.