12 things you Should never compost
I recently wrote an article that talked about a long list of weird things that you can compost which you might not have thought about. Today, I am going to discuss those things you should never compost.
Vegetable gardening is greatly enhanced by the addition of organic matter formed by composting.
If you enjoy growing vegetables, you will know how much better your vegetables will grow if you add compost around them.
The organic matter that is produced nourishes both the soil and the plant, resulting in healthy plants and high yields. 
Even though recycling and composting are 2 very important green practices to follow, there are definitely some items that are bad for the environment and should be avoided.
Never Compost these 12 items.
There are lots of common and not-so-common items that can be composted. Fortunately, the list of items that you should NOT add to the compost pile is not too long and makes quite a bit of sense.
For best results do not compost these items:
Pet waste from carnivorous animals.
Manure is fine, but pet feces from dogs and cats is a definite no-no. Your cat or dog feces can introduce parasites, which is the last thing you want to be adding to any garden meant for human consumption.
Meat scraps and bones
Most kitchen refuse is fine for the compost pile, but you will want to avoid any leftover meat and bones, which can attract vermin. Adding these also would make for a very foul-smelling compost pile.
It is particularly important not to use meat scraps if you use a direct composting method since the scraps will easily be able to be dug up.
Grease and oil
These products do not break down and can coat materials in the pile. They also attract unwanted pests. Never add either to a compost pile.
Diseased plants and weeds with seeds
Normally, adding plants to a compost pile is a good thing. However, adding plants with the disease, or those that still have seeds is not.
Throw these in the trash can instead. Otherwise, you risk transferring fungal or bacterial problems to plants you treat with the finished compost from the diseased plants.
Seeds from weeds will just make the problem with weeds worse since they might grow and prosper!
Chemically treated wood
Normal branches and small pieces of wood will break down. However chemically treated wood should not be added to a compost pile, since the chemicals might leach into the compost.
Milk products
These are attractive to vermin so should be avoided.
Glossy paper
This is better off recycled instead of composted. While it can be added if you shred it first, it takes longer to break down if added in whole pieces.
Sawdust
I know this is tempting but unless you know for sure that the wood was not treated with chemicals, avoid using it on the compost pile.
Walnut shells
These shells contain juglone, which is a natural aromatic compound toxic to some plants.
Items that can’t be recycled
This goes without saying but aerosols, chemicals, batteries, and other materials like this are a big no-no. If you can’t recycle it, don’t try to compost it!
Plastics
Plastic bags, lined cardboard boxes, plastic cups (including garden pots), plastic plant tags, plastic seal ties, and plastic labels on fruit should all be avoided.
None of these will break down in a compost pile.
Personal use items
Used personal products such as tampons, diapers, and items soiled in blood are a health risk. Dispose of them with trash, not in a compost pile.
Greens and browns for composting
Keep these two rules in mind when you are trying to compost green and brown materials. 1. Green is something which is living. 2. Brown is something that used to be living.
I am growing a lemon tree. Can I put the leaves from the tree in the compost? They do smell citris from the oils in the leaves. Just wanted to make sure. Thanks
Hi Joseph. yes, you can. Any garden refuse other than weeds with seeds in them are compostable. They will break down just fine although they might take longer than thinner leaves.
Carol
Do you think I could compost horseradish leaves? I have concerns that organic material that is somewhat “spicy” (think hot peppers) or could be invasive (like horseradish roots) might be a bad idea.
Thanks.
Hi John,
I think I would be careful about composting horse radish roots. They really can be very invasive and if the temp on your compost pile does not get hot enough to kill them, you could end up with it all over the garden if you spread the compost. Carol
What effect would black walnut leaves have on a compost pile ?
Hi Alvin. My research shows me that the feeling on this is mixed. Some say it is fine and others advise not to use it. I would be careful of adding anything to compost (Unless you can be 100% sure the heat of the pile gets high enough) that is harmful in the garden normally.
Carol
I sometime use Arm and Hammer carpet powder before I vacuum…would it still be OK to use the lint from the vacuum after that?
to be honest, Donna. I am not sure. I would think it would depend on the heat of the compost pile and whether you will be using the compost on vegetables instead of ornamental plants. I try to play it safe on compost that I will be using near veggies.
I put meat and dairy in my compost all the time, as well as bacon grease, and I have never had an issue with vermin of any sort…not even my dog;) If it’s summer, it’s good and hot and cooks down in nothing flat, in winter the freezing process seems to break it down rather quickly as well. In the spring and fall I usually add some enzymes to move things a little quicker, but not always. If you have a good layer of leaves or grass clippings on top there will be no smell. It’s really important to remember that a good, non smelly, compost cooks, it doesn’t rot.
Hi Kami I have had the opposite effect in my compost pile. It definitely attracts my dogs at the least if I put meat scraps in it. You seem to have just the right mix to combat this.
How do I know when I can start using my compost for my gardening pots?
Hi Hayley. It is hard to give an exact answer to this question, since it can vary greatly. Compost can take from a few months to a full year to be ready, depending on moisture, mix of brown and green and temperature. When the compost is ready it will look and smell like very dark soil. The pile shrinks as it decomposes but is ready when it is crumbly and has a rich earthy smell.
otherwise well-rotted compost.
The usable compost will have few ingredients that have not decomposed but you may still see some sticks, roots, and other intact plant parts in the finished compost. They can just be removed and added back to the compost pile that is not ready.
Carol
Hi, I have a question. For years (20) my dog has always pooped in a small area of the yard. I also have a organic composted pile 6’X8′ x 18″ deep. Last week the gardener was working around the dog poop area and removed some of the dark composted dog waste mixed with the sandy soil all the poop was decomposed. And he put it in my organic compost pile. I only use that soil on my trees and garden vegetable’s that are eatable. should this Dog mixture be remove from my compost pile?
Thank you , JIM
Hi Jim, Pet waste contains parasites that might not be killed in household compost piles. Unless you can guarantee the temperature of your compost pile, I would not recommend it.
Why are radishes ok to compost, but not horseradish? I’ve never grow horseradish, so I don’t know what it’s like. Thanks!!
Horseradish roots can be invasive, so some people use caution with them in composting. However, as long as your pile has the right mixture so that it “cooks” they should be fine.
Can you compost prepared horseradish?
Horseradish roots can be invasive, so many people take care or do not compost them. As far as prepared horseradish goes, I have not tried, so am unsure. Perhaps a reader can chime in with an answer.
I use a black plastic compost bin that was given to me by our local county after attending a composting course.it sits on the ground in my garden but it has tons of small roots growing up into it from under the compost. Should I put it on a solid bottom? Also, I have had chickens for many years and I put their pine shavingand straw bedding in the compost. How long do you think it takes for it to be safe to use?
Hi Frank, You can do it either way, either directly on the ground or on a hard surface. The mixture in the compost should kill any weeds growing in it if it is formulated with the right amount of green and brown material.
Wood and bark shavings can decompose into finished compost in as little as three months, especially during the summer when the pile’s center of the pile heats up.