15 Things You Should NOT Compost

Backyard Composting: 15 Things You Should Not Compost

There are some folks who compost just about anything, including pet manure and human manure. Others believe that it is absolutely necessary to stick to a strict list of what is okay to compost and what is not. For most backyard composters, it is okay to be somewhere in the middle, and you certainly will not ruin your compost bin if you accidentally toss a leftover turkey sandwich into it.

Here are the most common items you will find on lists of what not to compost, as well as the reasons most folks believe you should not compost them — so that you can decide what is right for your compost pile.

1. Weeds with seeds – If you missed some weeds before they went to seed and now are wondering what to do with them, it is best to just throw them in the trash. This may seem wasteful, but weed seeds in your compost bin will be spread with your compost throughout your vegetable garden or in your flowerbeds. Then, instead of your fresh layer of compost helping to limit weed growth, it will only makes things worse and you will really have a weed problem.

2. Dairy – Dairy, such as milk, butter and cheese, will break down, so it is not an absolute no-no for compost bins. However, the problem with dairy is that it will attract rodents, raccoons and other unwanted critters into your yard. It can also make your compost pile smell, so it is bet to avoid it.

Meats and Cooking Oils Are not Good for Compost

3. Dog and cat waste – It may be tempting to add pet waste to your compost pile, particularly since it is common practice to use manure in gardens. However, waste from animals that eat meat (and sometimes other weird and unknown things) is not a good addition to compost. These waste products could potentially add bad organisms into the compost that may not be eradicated through regular backyard composting and could pose a health risk if used around plants grown for food.

4. Sawdust – Sawdust is the type of thing most folks would likely add to a compost pile without much thought. All too often, sawdust comes from treated wood, which you definitely do not want in your compost. So unless you are sure that the sawdust is from untreated wood, it is best to not add it to your compost bin.

5. Meat, bones and most animal products – We all know that bodies decompose, which would make you think that it is okay to put animal products like meat, fish, bones or lard in with the rest of your kitchen scraps. However, while they will eventually break down, these products provide a big, smelly invitation to stray dogs, raccoons, rodents and other animals, so it is best to throw them in the trash.

6. Magazines, shiny or glossy paper, and colored paper – Synthetic materials used to coat glossy paper, dyes used to color paper and the inks used to print magazines often contain toxic materials that you do not want anywhere near plants that are grown for food. It may be possible to include some of these in a compost bin destined for ornamental beds only, but these are not good additions to compost piles, generally speaking.


7. Cooked or uncooked rice – Here is another one that most folks would probably think is just fine to add into their compost, but it is best to avoid both cooked and uncooked rice. Uncooked rice is going to attract rodents to your yard, while cooked rice can lead to the growth of unwanted bacteria.

8. Cooking oils – Cooking oils will also attract unwanted visitors and can make your compost pile smell, so try to avoid including them in your bin.

9. Plants sprayed with chemical herbicides or pesticides – Some chemical pesticides and herbicides may break down during the composting process, but others will not. It is best to avoid all pesticides and herbicides, since these can certainly affect your end product and the plants that are grown in it.

10. Coal ash – It may be tempting to throw the ashes from your charcoal barbecue into your compost, particularly because other types of ash are fine to add. However, this is one temptation you will definitely want to avoid, since commercial charcoal products (like briquettes) are often treated with chemicals that have no place in a compost bin. If you use an all-natural, wood charcoal, then it is okay to put the ashes in your compost pile.

Bread is Bad for Compost Bins

11. Bread – Breads, cookies, pastas, crackers and other flour-based products will break down, but they will definitely invite unwanted animals to come in your yard and mess with your compost pile.

12. Walnuts – In yet another unsuspected twist in the composting world, walnuts are a no-no. It would seem that something natural and healthy like a walnut would be just fine, but they contain juglone, which is toxic to some plants. So if you plan on using your compost around your prized tomato plants, you should know that this is just one type of plant that does not get along well with soil containing juglone.

13. Most personal care products – Flushable wipes, cotton balls, tampons and diapers are all things better sent to the garbage. Used personal care products may contain blood or other products that pose a health risk when added to compost, and some may be made from synthetic materials that will not break down in your compost bin.

14. Diseased plants – Some plant diseases can be destroyed through the composting process, but many backyard composting piles are not going to reach the level of heat required to accomplish this. To avoid spreading fungi, unwanted bacteria and other plant diseases, do not include diseased plants in your compost bin.

15. Plastic, metal and glass – This one may go without saying for most folks, but it is important to note that leftovers or spoiled foods need to be removed from their packages before being tossed in the compost bin. There are some compostable packaging materials that are designed to biodegrade right along with the leftovers you brought home from the restaurant, but most food packaging will not break down in your compost bin.

Remove Foods from Plastic Containers

What not to Compost: Final Thoughts

These are some of the most common products found on lists of what you should not compost; however, some of these products (as noted above) can actually be placed in a compost bin. The problem is that they may attract unwanted critters, may take a very long time to break down, or may make your compost bin smell.

To try to use as much waste as possible and to avoid these issues, some people maintain two or more compost bins. Placing common composting materials into one compost bin, and then having a second bin for more troublesome or longer lasting items is one way to use more of your kitchen scraps and leftover foods.

It should also be noted that there are lots of things that are okay to compost in small amounts or that are sometimes okay to compost and sometimes not. One example is oranges and other citrus fruits. While it is fine to include small amounts of citrus fruits in your compost bin, adding too many can upset the balance and make your compost too acidic.

Your Turn…

Do you have a compost pile or bin in your backyard? If so, what do you and don’t you compost?

Photo Credits (in order of appearance): morgueFile, Seemann; morgueFile, earl53; morgueFile, szafirek; morgueFile, Kymme; morgueFile, MaxStraeten