Compost in the Southwest


Compost is rich in the organic matter generally lacking in desert soils. Photo courtesy of Tucson Backyard Gardeners.

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International Compost Awareness Week (ICAW) is the first full week of May every year. To help you get started, here are tips for making compost in the Southwest. We will also have a giveaway for a Mantis countertop compost container later in the week – stay tuned for details!

In humid climates, instructions tell you to use two ingredients for compost, but here in the Southwest, there are three! Here we need green, brown and blue components to successfully create compost.

Earthworms consume decomposing matter but need cool soils, not hot compost piles.

Green ingredients are materials high in nitrogen, like banana peels and melon rinds. Brown materials are high in carbon, like fallen leaves, shredded newspaper or sawdust. Brown is also a shovel full of soil from your yard. It will contain the microorganisms required to do the actual composting.  Blue represents the water. Water is essential in the Southwest to keep everything moist so the decomposing microorganisms can survive to break down the brown and green materials.


“Green” kitchen waste is high in nitrogen.

Green Materials

citrus and melon rinds (citrus rinds contain vegetable oils and are fine.)
coffee grounds and tea bags
noninvasive grass clippings*
vegetable kitchen scraps

“Brown” shredded paper is high in carbon, an important component for creating compost.

Brown Materials

shredded paper – junk mail, newspaper, paper towels, etc.
dried leaves – palo verde, pine needles, etc.
sawdust or wood chips
wheat or sorghum straw
Add a shovel full of soil from your yard.

“Blue” – keep your compost moist to keep it decomposing.


water – keep your compost enclosed and moist

Eggshells are high in calcium, something most desert soils and desert hard water have in ample supply! (Caliche is calcium carbonate.)

Avoid these!

animal products such as meat, dairy, bacon grease (animal oils)
* Bermudagrass in any form (grass clippings, hay, horse manure)
weeds gone to seed

Avoid pests in your compost by screening it from intruders.

Compost Container

You will need a fully enclosed space. Open compost heaps and compost piles generally fail in the Southwest. Our air lacks humidity, thus materials quickly dry out and stop decomposing. There are numerous fully enclosed compost bin options on the market. If they have air vents, make sure the vents are screened to keep out insect pests. You can build your own bin with cinder blocks or 5-gallon buckets with lids, or simply dig a hole in the ground and compost in it. Just keep the compost covered to prevent evaporation.

Soil microbes will stay active as you turn your compost and keep it evenly moist.

Compost Creation
Add green and brown components as if you were making a giant lasagna. Add ample moisture, and keep the pile “cooking” by turning the compost with a shovel once a week. This helps mix the components and add necessary oxygen. Add more green and brown in equal portions anytime, and blue as needed. One month before you are going to harvest the compost, stop adding any new material, but continue to keep it moist.

Do not be alarmed if you find fungi in your compost. They are helping create compost.

If you live in Southeastern Arizona, please come to one of my lectures. Look for me at your local Pima County Library branch, Steam Pump Ranch, Tubac Presidio, Tucson Festival of Books and other venues. After each event I will be signing copies of my books, including “Month-by Month Guide for Arizona, Nevada and New Mexico”  from which this article is excerpted.  You can also purchase the book from the Products Reviews and Resources section of our website.

© Article is copyright by Jacqueline A. Soule. All rights reserved. Republishing an entire blog post or article is prohibited without permission. I receive many requests to reprint my work. My policy is that you may use a short excerpt but you must give proper credit to the author, and must include a link back to the original post on our site. Photos may not be used.

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3 comments on “Compost in the Southwest

  1. Katie Dubow

    Great post! I love my compost tumbler!

  2. Kristen

    Thank you for this helpful post! Why should eggshells be avoided? Is that unique to the SW, or is that just misinformation that I’ve heard previously?

    • Jacqueline Soule

      Eggshells would add calcium to our already excessively calcium-rich soils here in the Southwest. If you live in a mesic or humic area (like Wisconsin or Seattle) then you may wish to add eggshells to your compost.

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