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12 things you Should never compost

I recently wrote an article which talked about a long list of weird things that you can compost which you might not have thought about.   Today, I am doing to discuss those things you should never compost.

Vegetable gardening is greatly enhanced with adding 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. Not everything can be added to a compost pile. See my list of 12 common household items that you don't compost.

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 if fine for the compost pile, but you will want to avoid any left over meat and bones, which can attract vermin. Adding these also would make for a very foul smelling compost pile.

Don't add meat scraps and bones to the compost pile

Grease and oil

These products do not break down and can coat materials in the pile. They also attracts 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 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!

Don't compost weeds with seeds attached

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.

Milk products can attract vermin so they should not be composted

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.

Pile of sawdust

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.

Colorful plastic cups

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.

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Frank

Thursday 2nd of May 2024

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?

Carol Speake

Friday 3rd of May 2024

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.

Kati

Friday 15th of December 2023

Can you compost prepared horseradish?

Carol Speake

Wednesday 20th of December 2023

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.

Carol

Saturday 15th of October 2022

Why are radishes ok to compost, but not horseradish? I've never grow horseradish, so I don't know what it's like. Thanks!!

Carol Speake

Monday 17th of October 2022

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.

Jim Lambert

Friday 31st of May 2019

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

Carol

Friday 31st of May 2019

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.

Hayley

Thursday 26th of July 2018

How do I know when I can start using my compost for my gardening pots?

Carol

Thursday 26th of July 2018

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

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