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What to Compost

What to Compost

A lot of people have questions on what to compost.  One of the great benefits of having your own compost pile is to be able to truly create your own organic fertilizer.  Since you know where everything came from, you know it's green!

Materials to Use in Compost Piles

Our friends over at Organic Gardening Magazine provided us with this great list to simply a lot of the questions of what to put into a compost pile.

The general rule to a good compost pile is a 50/50 mix of brown and green materials.  So if you add a green material, make sure your next layer in the compost pile is a brown material.  Green materials are high in nitrogen and brown materials are high in carbon.

Green Materials

Brown Materials

Aquarium Water, Algae & Plants
Adds moisture and a kick of nitrogen. Use from freshwater tanks only.

Brown garden debris
Such as corn and sunflower stalks, dried legume plants, and dried potato and tomato vines, adds bulk to the pile.

Chicken Manure
High amounts of nitrogen, phosphorus, and potassium.

Black-and-White Newsprint & Office Paper
Can be used in the compost pile if you're desperate for brown materials, but they must be shredded. Try using the newspaper in sheet mulching projects and recycling office paper instead.

Dead Houseplants
Add a dose of nitrogen, but don't include thorny or diseased plants.

Best used in sheet mulching. Shred or chop it into small pieces if composting.

Fresh Grass Clippings
should be mixed with plenty of drier, brown material, or you'll risk creating a smelly pile.

Hedge Prunings & Twigs
Helps keep a pile fluffy but should be chipped first so they decompose faster.

Green Garden Debris
Such as spent pansies, bolted lettuce, and deadheaded flowers, can all be recycled in the compost bin.

An abundant carbon source and full of nutrients. Stockpile them in fall so that you have them on hand in summer.

Horse Manure
Contains more nitrogen than cow manure.

Pine Needles
Decompose slowly. Add only small amounts to your pile. Use excess needles as a mulch.

Manure from Pet Rabbits and Rodents
Can be composted with the accompanying wood or paper bedding.

Must be used in moderation, because it breaks down very slowly and can lock up nitrogen. Never use sawdust from treated or painted wood.

Vegetable Kitchen Scraps
Carrot peelings and the like should be buried in the pile so they don't attract animals. Eggshells are okay, crush them first as they may compost slowly.

Bulks up a pile, but it should not be confused with hay, which often contains weed and grass seeds and shouldn't be added to compost (unless you want to deal with the potential consequences).

Weeds can be composted! No joke. Just remember never to add weeds that have set seed or weeds that root easily from stems or rhizomes, such as field bindweed and Canada thistle.

Wood Ash
Adds potassium (potash), but it is an extremely alkaline material and should be used in small amounts.

Source: Organic Gardening Magazine

Also, to keep your compost pile truly organic, make sure your items came from a source free of pesticides, containments and toxins!

Desert Greenhouse Guideline: Another source for green material for composting is Coffee Grounds.  Desert soil is typically alkaline and coffee grounds are acidic.  Check out Starbucks Grounds for Your Garden program.

Questionable Compost Materials

Generally speaking, if you are not sure if you should put something in a compost pile, don't.  Here is a list of compost materials to help answer some of those questions.



Carnivore Manure

Dog, cat, pig, and reptile manures (and associated bedding) may contain parasites or dangerous pathogens that are harmful to humans, particularly pregnant women, children, and people with compromised immune systems. Never add them to your compost.


Natural-fiber cloth doesn't add any benefit to the compost pile. Consider using burlap bags under wood chips to prevent weeds instead.

Cow Manure

Cow manure may contain E. coli O157:H7, a very dangerous pathogen that can cause severe illness and even death. "It's hard to meet time and temperature requirements to kill pathogens in a home compost pile," says soil scientist Craig Cogger, Ph.D. We don't recommend adding it to home compost ever because of the health risk. But if you're tempted to use it, you must wait at least four months after you add it to your soil before you can harvest, to make sure the pathogens are no longer active. Wear gloves when handling manure and wash your hands thoroughly.

Diseased plants

Diseased plants must be disposed of in the garbage or burned. Adding them to compost could spread the disease.

Dryer Lint

Dryer lint may contain synthetic fibers that will never decompose. Even natural-fiber lint adds no benefit to compost.

Glossy Paper

Paper, especially glossy paper, printed with colored ink, may contain heavy metals. Black-and-white newspaper is safe.


Gypsum board scraps could contain paint and other undesirable toxins.


Human and pet hair can be added in small amounts, if you keep in mind that it breaks down slowly, mats easily, and sheds water.

Meats, dairy products, bones, and fish

Meats, dairy products, bones, and fish decompose slowly, smell, and attract animals.


Sawdust must be used in moderation, because it breaks down very slowly and can lock up nitrogen. Never use sawdust from treated or painted wood.

Unknown Sources of Clippings

Materials from the side of the road, including grass clippings and leaves, could contain petroleum residues (such as oil), toxins, and nonbiodegradable materials.

Vacuum Bags

Vacuum bags may contain synthetic carpet fibers and other nonbiodegradable items.

Wood Chips

Wood chips should be used as mulch around ornamentals because they break down so slowly.

Source: Organic Gardening Magazine

When Things Go Wrong

Remember, a good compost pile should not smell foul.  If you find your pile has an odor, is attracting flies or is slow to decompose, there is an issue that needs to be addressed.

ConcernPossible Cause & Solution

Pile is dry

A dry pile will be slow to decompose, there may be too much wood material or it just need to be wet down.  Turn the compost pile and add enough water to make it the consistency of a wrung out sponge.

Pile is too wet

An overly wet will be starved of oxygen (essential to the decomposition process) and may begin to smell.  Add some brown materials and turn the pile.

Pile has an odor

There is either too much green material or is too wet.  Add more brown material and turn the pile.

Pile is attracting flies

Make sure to cover organic waste such as manure and kitchen scraps, both of which attract flies.

Pile is not composting

If your pile is moist and still not decomposing, you most likely need to add more green material and turn the pile.

Desert Greenhouse Guideline: Keeping a compost pile moist can be a challenge for some gardeners in the hot, dry desert climate. Be sure to check often that your compost pile has enough moisture to keep the compost process going.

Finished Product

When you compost pile has reduced to one-third its original size and the internal temperature has dropped, that is a really good indicator your compost is ready to use!  Use a sifter to removed any material that is not composted and use it in the next pile.


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