{"id":786,"date":"2025-10-17T09:56:36","date_gmt":"2025-10-17T16:56:36","guid":{"rendered":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/?page_id=786"},"modified":"2026-04-06T10:50:51","modified_gmt":"2026-04-06T17:50:51","slug":"chapter-6-composting","status":"publish","type":"page","link":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/chapter-6-composting\/","title":{"rendered":"Chapter 6: Composting"},"content":{"rendered":"<div class=\"wsu-hero wsu-width--full wsu-pattern--wsu-light-radial-left  wsu-hero--style-boxed \">\n\t<div class=\"wsu-hero__background\">\n\t\t<div class=\"wsu-image-frame wsu-image-frame--fill\">\n\t<img decoding=\"async\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/08\/AdobeStock_769579077.jpg\"\n\t\tsrcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/08\/AdobeStock_769579077.jpg 1350w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/08\/AdobeStock_769579077.jpg 300w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/08\/AdobeStock_769579077.jpg 1024w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/08\/AdobeStock_769579077.jpg 768w\"\n\t\tsizes=\"(max-width: 1350px) 100vw, 1350px\"\n\t\talt=\"Hands diligently compost food waste into compost bin in backyard garden, fostering sustainability and eco-consciousness. Environmental stewardship, promoting organic recycling and soil enrichment.\"\n\t\tstyle=\"object-position: 65% 84%\"\n\t\t\/>\n<\/div>\n\t<\/div>\n\t<div class=\"wsu-hero__overlay\">\n\t<\/div>\n\t<div class=\"wsu-hero__content-wrapper\">\n\t\t<div class=\"wsu-hero__inner-content-wrapper\">\n\t\t\t\t\t\t<div class=\"wsu-hero__title-wrapper\">\n\t\t\t\t<h1 class=\"wsu-hero__title\">Composting<\/h1>\t\t\t\t<div class=\"wsu-hero__caption\">Chapter 6<\/div>\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<div class=\"wsu-hero__content\">\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n\n\n\n<p class=\"wsu-max-width--hero wsu-spacing-after--xsmall\"><strong>Craig Cogger<\/strong>, Soil Scientist Emeritus, Department of Crop and Soil Sciences, Washington State University<\/p>\n\n\n\n<p class=\"wsu-max-width--hero wsu-spacing-after--xsmall\"><strong>Andy Bary<\/strong>, Senior Scientific Assistant, Puyallup Research and Extension Center, Washington State University<\/p>\n\n\n\n<p class=\"wsu-max-width--hero wsu-spacing-after--xsmall\"><strong>Dan Sullivan<\/strong>, Professor Emeritus, Department of Crop and Soil Science, Oregon State University<\/p>\n\n\n\n<p class=\"wsu-max-width--hero wsu-spacing-after--xsmall\"><strong>Jim Kropf<\/strong>, Pierce County Extension Director, Agricultural and Natural Resources Unit, Washington State University<\/p>\n\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n<div class=\"wsu-row wsu-row--sidebar-right\" >\r\n    \n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<h2 class=\"wp-block-heading wsu-font-size--xlarge wsu-heading--style-marked wsu-spacing-after--xxmedium\" id=\"learning-objectives\">Learning Objectives<\/h2>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>Realize the importance of composting for improving garden soils as well as for reducing the amount of waste in landfills or other waste treatment facilities.<\/li>\n\n\n\n<li>Understand the biological principles of the composting process.<\/li>\n\n\n\n<li>Understand effective methods and suitable materials for successful composting.<\/li>\n<\/ul>\n\n<\/div>\r\n\n\n<div class=\"wsu-column\"  style=\"\">\r\n\t\n\n<h2 class=\"wp-block-heading\">Topics Covered<\/h2>\n\n\n\n<ul class=\"wsu-menu--style-sidebar\">\n<li><a href=\"#ch6-introduction\" data-type=\"internal\" data-id=\"#ch6-introduction\">Introduction<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-science-of-composting\" data-type=\"internal\" data-id=\"#ch6-science-of-composting\">The Science of Composting<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-managing-the-decay\" data-type=\"internal\" data-id=\"#ch6-managing-the-decay\">Managing the Decay Process<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-how-to-compost\" data-type=\"internal\" data-id=\"#ch6-how-to-compost\">How to Make Compost<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-composting-in-community\" data-type=\"internal\" data-id=\"#ch6-composting-in-community\">Compost Use, Health, and Safety Questions<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-composting-in-community\" data-type=\"internal\" data-id=\"#ch6-composting-in-community\">Composting in Community Gardens<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-vermicomposting\" data-type=\"internal\" data-id=\"#ch6-vermicomposting\">Vermicomposting<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-compost-in-gardens\" data-type=\"internal\" data-id=\"#ch6-compost-in-gardens\">Using Compost in Gardens and Landscapes<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-composting-and-environment\" data-type=\"internal\" data-id=\"#ch6-composting-and-environment\">Composting and the Environment<\/a><\/li>\n\n\n\n<li><a href=\"#ch6-further-reading\" data-type=\"internal\" data-id=\"#ch6-further-reading\">Further Reading<\/a><\/li>\n<\/ul>\n\n<\/div>\r\n\n<\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-introduction\">Introduction<\/h2>\n\n\n\n<p>Gardeners have long made and used <a href=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#c\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#c\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>compost<\/strong> (opens in new window)<\/a> because it helps improve garden soil. Home composting transforms yard debris and food scraps into valuable soil amendments and closes the recycling loop in our own backyards (Figure 1). Today, many cities have municipal composting programs. These programs include curbside yard and food debris collection, large-scale composting at commercial facilities, and resale of the finished compost to gardeners and landscapers. Nonetheless, backyard composting remains popular in areas without municipal programs and for gardeners who want to make and use their own compost.<\/p>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none wsu-spacing-margin-left--xxmedium\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_1.jpg\" alt=\"Peppers ripening within cages in a garden.\" class=\"wp-image-2636\" width=\"500\" height=\"374\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_1.jpg 900w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_1-300x225.jpg 300w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_1-768x576.jpg 768w\" sizes=\"(max-width: 500px) 100vw, 500px\" \/><figcaption class=\"wp-element-caption\">Figure 1. Peppers growing in a garden bed amended with backyard compost. (Photo by Craig Cogger.)<\/figcaption><\/figure><\/div>\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-science-of-composting\">The Science of Composting<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><em>The Cycle of Growth and Decay<\/em><\/h3>\n\n\n\n<p>Composting carries out part of the earth\u2019s biological cycle of growth and decay. Plants grow by capturing the sun\u2019s energy along with carbon dioxide from the air and nutrients and water from the soil. When plants (and the animals that eat them) die, they become raw materials for the decay process. Bacteria, fungi, insects, worms, mites, and other creatures convert some of the carbon from dead plants into energy for their own metabolism, releasing carbon dioxide into the air. They also cycle some of the carbon and nutrients from the decaying plants into their own bodies as they grow, and eventually back into the soil, where the cycle begins again. The material that remains from the decay process is similar to soil organic matter. It holds water and nutrients in the soil and makes the soil more porous and easier to dig.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Fast Composting<\/em><\/h3>\n\n\n\n<p>Gardeners can manipulate the decay process to make it proceed faster. We do this by balancing food, water, and air in the compost pile to favor the growth of <a rel=\"noreferrer noopener\" href=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#t\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#t\" target=\"_blank\"><strong>thermophilic<\/strong> (opens in new window)<\/a> (high-temperature) microorganisms. One byproduct of microbial activity is heat. When conditions are favorable for high-temperature microorganisms, compost piles heat rapidly to 130\u00b0F\u2013150\u00b0F. This temperature range kills most weed seeds and pathogens (disease organisms; refer to <em>Composting to Reduce Weed Seeds and Plant Pathogens<\/em> listed in Further Reading for more information). Once the hot phase is complete, lower temperature bacteria along with fungi, worms, insects, and other organisms complete the decay process.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Slow Composting<\/em><\/h3>\n\n\n\n<p>If gardeners do not maintain ideal conditions for hot composting, microorganisms will still break down the plant remains, similar to what happens to organic residues in soil. Decay will be slower, cooler, and less effective at killing weed seeds and pathogens.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-managing-the-decay\">Managing the Decay Process<\/h2>\n\n\n\n<p>You can affect the speed of the composting process and the quality of the compost product by managing the factors described below.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Food (Raw Materials)<\/em><\/h3>\n\n\n\n<p class=\"wsu-spacing-after--large\">For relatively fast composting, the initial mix must have the proper moisture and air content as well as organic materials that provide a rich energy and nutrient source for bacteria. Table 1 and Figure 2 show some materials commonly used in making compost. They are separated into \u201cbulking\u201d, \u201cenergy\u201d and \u201cbalanced\u201d materials.<\/p>\n\n\n<span id=\"tablepress-124-description\" class=\"tablepress-table-description tablepress-table-description-id-124\">Table 1. Examples of raw materials for making compost.<\/span>\n\n<table id=\"tablepress-124\" class=\"tablepress tablepress-id-124\" aria-describedby=\"tablepress-124-description\">\n<thead>\n<tr class=\"row-1 odd\">\n\t<th class=\"column-1\">Bulking Agents<br \/><small>(Low moisture, high porosity, <br>low nitrogen)<\/small><\/th><th class=\"column-2\">Energy (Green) Materials<br \/><small>(High moisture, low porosity, <br>high nitrogen)<\/small><\/th><th class=\"column-3\">Balanced, Raw Materials<br \/><small>(Low to medium moisture, <br>medium porosity, low to medium nitrogen)<\/small><\/th>\n<\/tr>\n<\/thead>\n<tbody class=\"row-hover\">\n<tr class=\"row-2 even\">\n\t<td class=\"column-1\">chipped trees and shrubs<\/td><td class=\"column-2\">garden trimmings<\/td><td class=\"column-3\">deciduous leaves<\/td>\n<\/tr>\n<tr class=\"row-3 odd\">\n\t<td class=\"column-1\">sawdust<\/td><td class=\"column-2\">fruit and vegetable waste<\/td><td class=\"column-3\">horse manure with bedding<\/td>\n<\/tr>\n<tr class=\"row-4 even\">\n\t<td class=\"column-1\">wheat straw<\/td><td class=\"column-2\">grass clippings<\/td><td class=\"column-3\">spoiled hay<\/td>\n<\/tr>\n<tr class=\"row-5 odd\">\n\t<td class=\"column-1\">corn stalks<\/td><td class=\"column-2\">livestock manure<\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<tr class=\"row-6 even\">\n\t<td class=\"column-1\">Christmas trees (chipped)<\/td><td class=\"column-2\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td><td class=\"column-3\"><span class=\"wsu-screen-reader-only\">Not applicable<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<!-- #tablepress-124 from cache -->\n\n\n\n<figure class=\"wp-block-image size-large is-resized wsu-spacing-before--large wsu-spacing-after--large\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_2-1024x336.jpg\" alt=\"Three side by side photos of a mixture of various organic debris, including grass clippings on the left, straw in the middle, and a mixture of the grass, leaves, and straw on the right.\" class=\"wp-image-2637\" width=\"1167\" height=\"383\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_2-1024x336.jpg 1024w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_2-300x98.jpg 300w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_2-768x252.jpg 768w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_2-1536x503.jpg 1536w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_2-2048x671.jpg 2048w\" sizes=\"(max-width: 1167px) 100vw, 1167px\" \/><figcaption class=\"wp-element-caption\">Figure 2. Examples of raw materials: bulking agent (straw), (left), energy source (grass clippings), (middle), and a mixture of grass clippings, leaves, and straw (right). (Photos by Andy Bary.)<\/figcaption><\/figure>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Energy Materials<\/h4>\n\n\n\n<p>Energy materials provide the nitrogen and high-energy carbon compounds needed for fast microbial growth. If piled without bulking agents, these materials usually are too wet and dense to allow much air into the compost pile. The pile will become <a href=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#a\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#a\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>anaerobic<\/strong> (opens in new window)<\/a> (lacking oxygen) and produce foul, rotten odors.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Bulking Agents<\/h4>\n\n\n\n<p>Bulking agents (Figure 5) are dry, porous materials that help aerate the compost pile. They are too low in moisture and nutrients to decay quickly on their own.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Balanced, Raw Materials<\/h4>\n\n\n\n<p>Some raw materials contain a balance of energy and bulking agent properties. These materials will compost readily without being blended with other ingredients. Examples include deciduous leaves, horse manure mixed with bedding, and spoiled alfalfa hay. These materials are handy for ensuring the success of hot compost piles.<\/p>\n\n\n\n<p>Mixing bulking agents with energy sources provides a balance of moisture, air, and nutrients for rapid composting. A mixture of one part energy materials with two parts bulking agents (by volume) usually gives a reasonable mix for rapid composting.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Particle Size<\/em><\/h3>\n\n\n\n<p>Grinding, cutting, smashing, or chipping raw materials reduces particle size. Small particles have more surface area for microbial activity and are easier to mix. Woody branches that have not been chipped often make it difficult to turn a pile. They also decompose very slowly. Grind or chip woody branches to use as bulking agent or mulch, pile them separately, or place them in a municipal yard debris container.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Mixing<\/em><\/h3>\n\n\n\n<p>Mixing raw materials stimulates the composting process by balancing moisture, aeration, and nutrients throughout the pile. Mix materials thoroughly when building the pile. Avoid layering.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Pile Size<\/em><\/h3>\n\n\n\n<p>The pile must be big enough to hold heat. A hot pile decays much faster than a cold pile. Small piles are usually colder because they have small cores that hold less heat. Small piles also dry out faster. A pile of about one cubic yard is big enough for year-round composting, even in cold-winter areas.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Moisture<\/em><\/h3>\n\n\n\n<p>The mixed material should feel moist, but you should not be able to squeeze water out of it with your hands. Piles that are too dry limit microbial growth. Piles that are too wet reduce the movement of oxygen, which also limits microbial growth. When conditions are dry, you may need to add water to maintain pile moisture. In rainy winter locations, a pile may not heat up unless you cover it to keep out rainwater. Check moisture when you turn the pile.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Aeration<\/em><\/h3>\n\n\n\n<p>The microorganisms responsible for fast decomposition need oxygen. In the pile, oxygen is consumed by microbes. If oxygen is not replenished, the pile can become anaerobic (without oxygen) and produce foul odors. The pile needs to be porous enough to pull outside air into it. Use enough bulking agents to create a porous pile. As the pile decomposes, it settles, reducing aeration. Turning the pile or adding bulking agents helps restore porosity and maintain air circulation.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Microorganisms<\/em><\/h3>\n\n\n\n<p>Raw materials used to form a compost pile usually contain all the microorganisms needed to make compost. You do not need to add soil or compost starters with \u201cspecial\u201d microorganisms.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Nutrients<\/em><\/h3>\n\n\n\n<p>Just like people, microorganisms need nutrients (such as nitrogen, phosphorus, sulfur) to grow and reproduce. These nutrients occur in the raw materials used in the compost mix. Additional fertilizer from any source (organic or inorganic) usually is not needed. Nitrogen fertilizer may be beneficial for mixes consisting mainly of bulking agents. The best way to supply nitrogen is to add energy materials or organic nitrogen fertilizer and mix them well throughout the pile.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Piles vs. Bins<\/em><\/h3>\n\n\n\n<p>You do not need a bin or other container to make compost (Figure 3). Piles work well. Some people prefer containers because they look neater, or because it is easier to shield them from pests. Containers can be simple or fancy. Make them from materials such as old pallets, lumber, mesh fencing, or cinder blocks. You can also purchase premade bins. For hot compost, each bin should be at least three feet by three feet by three feet in size. Avid composters often have three bins: two for turning and one for <a href=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#c\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#c\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>curing<\/strong> (opens in new window)<\/a> compost.<\/p>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none wsu-spacing-margin-left--xxmedium\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_3.jpg\" alt=\"Large pile of tree mulch or wood chips.\" class=\"wp-image-2645\" width=\"528\" height=\"390\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_3.jpg 657w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_3-300x221.jpg 300w\" sizes=\"(max-width: 528px) 100vw, 528px\" \/><figcaption class=\"wp-element-caption\">Figure 3. Freestanding piles can be used for fast or slow composting. (Photo by Andy Bary.)<\/figcaption><\/figure><\/div>\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-how-to-compost\">How to Make Compost<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Slow (Cold) Composting<\/em><\/h3>\n\n\n\n<p>Slow composting is an easy way to turn yard waste into a useful soil amendment. It is often the best method for people who do not have the time to tend a hot compost pile. A two-pile, two-year system gives ample time for most raw materials to decompose.<\/p>\n\n\n\n<p>Start by mixing non-woody yard waste into a pile and letting it sit for a year or more. Microorganisms, insects, earthworms, and other decomposers will slowly break down the waste. A mixture of energy materials and bulking agents provide the best food source and environment for decomposition (Table 1). Cutting long stems and smashing or shredding coarse materials into smaller pieces also improves decomposition. The best time to start a slow pile is when you are collecting a lot of yard waste, such as during spring or fall garden cleanup.<\/p>\n\n\n\n<p>During the first year, you can add fresh yard waste or fruit and vegetable scraps to the pile. Open the pile, place fresh yard debris in the center and mix, then cover it. This helps loosen the pile to improve aeration and also buries the fresh material so it does not attract pests. After a year, turn the pile, and let it sit for another year, without adding any fresh material. Often you will find poorly decomposed stems and rinds in the year-old pile. You can recycle these materials as bulking agents when you build a new pile. Even after two years, some stems will not be fully decomposed. Simply mix them into the garden soil along with the rest of the compost, where they will continue to decay.<\/p>\n\n\n\n<p>Fruit and vegetable scraps are particularly appealing to pests, such as flies, rats, and raccoons. To avoid pests, fully bury these scraps within the pile. If you bury the vegetable waste in the pile and pests are still a problem, you may need to use a pest-resistant bin (Figure 4) or keep vegetable waste out of the pile. Other options for vegetable scraps are municipal yard waste containers (in communities where yard and food waste are collected), worm bins, or direct burial in the garden. For more information on worm bins refer to Composting with Worms in the Further Reading section.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized wsu-spacing-after--large wsu-spacing-before--large\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_4.jpg\" alt=\"Screened outdoor composting unit with three different compartments and a corrugated metal roof.\" class=\"wp-image-2649\" width=\"1086\" height=\"455\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_4.jpg 900w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_4-300x126.jpg 300w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_4-768x322.jpg 768w\" sizes=\"(max-width: 1086px) 100vw, 1086px\" \/><figcaption class=\"wp-element-caption\">Figure 4. Three-bin composting unit with pest protection. This level of construction is not needed for most backyard composting but is useful for those who prefer a neat, pest-proof system. (Photo by Andy Bary.)<\/figcaption><\/figure>\n\n\n\n<p>Slow composting does not produce enough heat to kill many weed seeds, rhizomes, or pathogens. It is best to pull and compost weeds before they go to seed. If you have a municipal yard waste container, you can use it for weeds with seeds, rhizomes, and diseased plants. Compost piles at the commercial facilities that receive municipal yard waste are managed to generate the heat needed to kill weed seeds and pathogens.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><em>Fast (Hot) Composting<\/em><\/h3>\n\n\n\n<p>If you create and maintain a balance of air, moisture, and energy for the compost microorganisms, they will produce a hot compost that will break down quickly and kill off many weed seeds and disease organisms. Making hot compost takes extra effort, but it produces a high-quality product within a few months. One method for making hot compost is described in the next section.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--xsmall\">Building the Pile<\/h4>\n\n\n\n<ol>\n<li>Collect enough material to make a pile at least one cubic yard in volume (an open pile five feet by five feet at the base and three feet high holds about a cubic yard). You need roughly two parts bulking agent to one part energy material (Table 1). Chop, shred, mow, or smash coarse materials so they will break down faster.<\/li>\n\n\n\n<li>Start the pile by combining energy material and bulking agent, mixing with a pitchfork as you add the materials.<\/li>\n\n\n\n<li>Squeeze a handful of the mixed material to check its moisture level. If you can barely squeeze out a drop of water, the moisture level is ideal. If the pile is too dry, add water and check the moisture again. If it is too wet, mix in some drier material.<\/li>\n\n\n\n<li>Continue adding energy material and bulking agent, mixing and checking moisture until the pile is built.<\/li>\n<\/ol>\n\n\n<div class=\"wp-block-image wsu-spacing-after--none wsu-spacing-margin-left--xxmedium\">\n<figure class=\"alignright size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_5.jpg\" alt=\"Green leafy vines, stalks, and other organic debris laid atop a compost pile.\" class=\"wp-image-2651\" width=\"521\" height=\"366\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_5.jpg 900w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_5-300x211.jpg 300w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_5-768x539.jpg 768w\" sizes=\"(max-width: 521px) 100vw, 521px\" \/><figcaption class=\"wp-element-caption\">Figure 5. Garden trimmings collected for composting. The trimmings will be chopped into smaller pieces and mixed with bulking material to make a suitable mix for fast composting. (Photo by Dan Sullivan.)<\/figcaption><\/figure><\/div>\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Turning the Pile<\/h4>\n\n\n\n<p>Use a pitchfork to turn the pile weekly for the first four to six weeks, and add water when needed. Turning improves the porosity of the pile and speeds biological decay. Turning also mixes material from the outside of the pile into the hot center. Cover the pile during rainy periods so it will not get too wet.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Curing Phase<\/h4>\n\n\n\n<p>After initial mixing, a carefully tended pile will often heat to 120\u00b0F to 150\u00b0F (hot to the touch) for several days to several weeks, as thermophilic bacteria break down the most easily decomposable material. The pile will shrink to about half its original volume during the hot phase. The pile then needs to sit for another two to three months to cure. Temperatures fall during curing to 80\u00b0F or less. Microbial breakdown continues during curing, but at a slower rate. The compost is ready to use when at least three months have passed since initial mixing, the pile no longer heats when turned, and the material looks dark and crumbly.<\/p>\n\n\n\n<p>Curing affects the availability of nitrogen, reduces microbial activity, and reduces the potential for <a href=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#p\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#p\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>phytotoxicity<\/strong> (opens in new window)<\/a>. Uncured compost may contain phytotoxins that harm some plants. Phytotoxicity most likely occurs when compost is used in potting soil or to start seeds. Complete curing is less critical when small amounts of compost are worked into garden soil.<\/p>\n\n\n<div class=\"wsu-callout wsu-border--color-vineyard wsu-callout--style-basic wsu-color-background--gray-5 wsu-border--add-left wsu-align-item--center wsu-spacing-after--large wsu-spacing-before--large wsu-max-width--xmedium\" >\r\n        \n\n<h4 class=\"wp-block-heading has-text-align-center\">What if my hot compost isn\u2019t hot?<\/h4>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--none wsu-font-size--xmedium\">If the pile is dry\u2026<\/h4>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>It needs more moisture.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--none wsu-font-size--xmedium\">If the pile is mostly bulking agent\u2026<\/h4>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>It needs more nitrogen. Add energy materials or nitrogen fertilizer.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--none wsu-font-size--xmedium\">If the pile is too wet\u2026<\/h4>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>Add more bulking agent. Cover the pile or build a larger pile during the rainy season.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--none wsu-font-size--xmedium\">If the pile has a foul smell\u2026<\/h4>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>It needs more air and less water. Try turning the pile more often or adding more bulking agent.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--none wsu-font-size--xmedium\">If the pile is too small\u2026<\/h4>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>It will not hold the heat.<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--none wsu-font-size--xmedium\">If it is cold outside\u2026<\/h4>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>Try building a larger pile to hold the heat.<\/li>\n<\/ul>\n\n\n\n<p class=\"has-text-align-center\">Sometimes you may have several problems to overcome. <br>If you cannot get the pile to heat, all is not lost, because the <br>pile will still break down by the slow method.<\/p>\n\n<\/div>\r\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-compost-use\">Compost Use, Health, and Safety Questions<\/h2>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\"><em><strong>Are there any plant materials to keep out of a compost pile?<\/strong><\/em><\/p>\n\n\n\n<p>If you are composting by the slow method, keep diseased plants, seed heads, and rhizomes (runners) of weeds out of your compost pile. Also keep woody branches out of the pile, unless you can grind, shred, or chip them to a smaller size.<\/p>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\"><em><em><strong>Can I put food waste in the compost pile?<\/strong><\/em><\/em><\/p>\n\n\n\n<p>You can compost fresh fruit and vegetable scraps, taking care to avoid pest problems, as described previously. Do not put other types of food scraps (such as meat, cheese, fats, baked goods) in home compost piles, because they often cause pest and odor problems. Some municipalities will accept other food scraps in green waste containers that are picked up curbside. Check with your local municipality to find out what is allowed.<\/p>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\"><em><em><strong>Can a compost pile catch on fire?<\/strong><\/em><\/em><\/p>\n\n\n\n<p>A compost pile will only ignite if it is a large pile that has a very hot zone next to a dry zone. Fires will not start in moist piles or in small, backyard piles.<\/p>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\"><em><em><strong>Do I need to screen home compost before using it?<\/strong><\/em><\/em><\/p>\n\n\n\n<p>It is not necessary to screen home compost when mixing it into garden soil or using it as mulch, even though the compost does not look as attractive as a commercial product. Partially decomposed plant debris in the unscreened compost will continue to slowly decompose in the soil. Screening is important if you use the compost in a potting mix or to start seeds. A 1\/2-inch screen should produce material suitable for use in a potting mix.<\/p>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\"><em><em><strong>Can I use manure in my compost?<\/strong><\/em><\/em><\/p>\n\n\n\n<p>Fresh animal manures sometimes contain pathogens that cause diseases in humans. <em>Salmonella<\/em> sp. and <em>E. coli<\/em> O157:H7 bacteria are among the most serious pathogens found in animal manure. These pathogens are not taken up into plants, but they can adhere to roots or low-growing leaves and fruits. The greatest risk from manure-borne pathogens is for root crops such as carrots, leaf crops such as lettuce, and fruit crops such as strawberries. The risk is negligible for any crop that is cooked thoroughly before eating.<\/p>\n\n\n\n<p>Pathogens in manure die off in the environment over time. Thorough, high-temperature composting kills pathogens, but it is difficult to maintain these conditions in a backyard compost pile. You can limit exposure to pathogens by excluding fresh manure from backyard compost that will be used on fresh garden crops. Allowing one year or longer for pathogens to die before applying compost to the garden also reduces pathogen risk.<\/p>\n\n\n\n<p>Do not put dog or cat manure in your compost pile. Some of the parasites found in these manures may survive for long periods and remain infectious to people. For more information on animal manure refer to <em>Fertilizing with Manure<\/em>, which can be found in the Further Reading section. For more information on compost use and food safety, refer to the Food Safety links in the Additional Resources section.<\/p>\n\n\n\n<p>Another concern with manure is the occasional occurrence of persistent herbicides that can contaminate compost. Most herbicides break down during composting and do not affect the quality of the compost. Two herbicides used in commercial agriculture, clopyralid and aminopyralid, are the exception. If they are present at harmful levels in compost, they can injure some garden plants, including plants in the nightshade (tomatoes, peppers, potatoes) and legume (beans and peas) families. They do not harm animals, people, or insusceptible plants. Neither herbicide is labelled for use on home lawns.<\/p>\n\n\n\n<p>These herbicides are sometimes present in grass hay sold for animal feed or in straw sold for bedding. Because these herbicides do not break down in the animal\u2019s gut, they pass through with the manure. If you purchase grass hay or straw for your animals and plan to compost their manure to use on garden crops, check with your supplier first to ensure that these herbicides were not used by the farmer.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-composting-in-community\">Composting in Community Gardens<\/h2>\n\n\n\n<p>Community gardens can provide gardeners with opportunities for composting on a larger scale. Larger volumes of garden waste mean that it is easier to collect enough waste at one time to practice hot composting. But larger volumes of garden waste can also increase odor and pest problems if composting is not well managed.<\/p>\n\n\n\n<p>To make compost successfully, a community garden needs a person or a team to take responsibility for composting. Responsibilities include managing the garden waste, building and managing compost piles, and educating fellow gardeners about garden waste and composting in the community garden. One option for community garden composting is to use multiple bins of different sizes or number based on the amount of garden waste produced. Another option is a long pile with fresh materials added to one end and finished compost removed from the other end.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-vermicomposting\">Vermicomposting<\/h2>\n\n\n\n<p>Yard and food waste make up a major component of residential solid waste in Washington. Although much of this organic waste can be composted in the backyard, traditional composting methods are less effective during cold winter weather and are not practical for apartments.<\/p>\n\n\n\n<p><a href=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#v\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/glossary\/#v\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>Vermicomposting<\/strong> (opens in new window)<\/a>, or composting with worms, is an alternative to traditional backyard composting for recycling kitchen waste. Worm composting uses worms to recycle kitchen waste (typically vegetable and fruit trimmings as well as coffee and tea grounds) and other organic materials into worm castings, or vermicompost, an excellent soil amendment. This is an efficient way to divert kitchen waste from landfills.<\/p>\n\n\n\n<p>Setting up a worm bin is easy. Worm bins should be located where the temperature and moisture can be controlled, typically indoors. The ideal temperature range for worm composting is between 59\u00b0F and 77\u00b0F. Temperatures above 80\u00b0F will kill worms, while temperatures below 50\u00b0F will render them inactive. Keep the worm bin moist, and make sure the environment inside receives good air circulation. A convenient location for both feeding and bin maintenance is ideal.<\/p>\n\n\n\n<p>Selecting the appropriate worm bin size depends on the average amount of weekly generated food waste. A 14-gallon plastic bin (about two cubic feet) can handle about two pounds of kitchen waste a week, enough for a typical family of two. A bin or box measuring one foot high by two feet deep by three feet long (six cubic feet) can handle about six pounds of kitchen waste per week. This is the average amount of food waste for a family of four to six people.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Supplies for Vermicomposting<\/h3>\n\n\n\n<p>Many containers are suitable for worm bins, but plastic containers and home-built plywood boxes are popular choices. Worms avoid light, so keep the container dark inside. A tight-fitting lid is essential for keeping pests out. Drainage and aeration holes in the container are required. They can be located on the sides, top, or bottom. A drip collection tray under the bin is recommended if there are drainage holes in the bottom of the bin. Never reuse containers that have been used for storing chemicals or other toxic products. Refer to the Additional Resources section for more information on vermicomposting, including worm bin construction details and photos. Worm bin construction plans are also available from many Extension offices, county solid waste departments, or other online sources.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--small\">Type and Quantity of Worms to Use<\/h3>\n\n\n\n<p>Nightcrawlers and other garden earthworms are an important component of healthy soils, although they will not survive in a worm box. Two varieties of red worms are well adapted to worm boxes: <em>Lumbricus rubellus<\/em> and <em>Eisenia foetida<\/em>. These red worms feed on the surface of all types of organic matter.<\/p>\n\n\n\n<p>The number of worms required for a worm box depends on the daily weight of added food waste. Worms are measured by weight rather than number because they can eat their own weight in food in 24 hours.<\/p>\n\n\n\n<p>Two pounds of worms are needed for each pound of kitchen waste added per day, a ratio of 2:1. For example, if you produce 3.5 pounds of kitchen waste per week (1\/2 pound per day), use one pound of worms.<\/p>\n\n\n\n<p>Check with Master Gardener or Master Composter volunteers at your local Extension office or solid waste department for earthworm sources.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Bedding<\/h4>\n\n\n\n<p>Start by putting bedding in the worm box. Corrugated cardboard, newsprint, and newspaper shredded in one-inch-wide strips make excellent bedding. Do not use glossy paper. Worms need some grit for breaking down their food. Add a little topsoil (1\/4 cup per cubic foot of bin space) for this purpose. Worms should be added to the bedding with their first feeding.<\/p>\n\n\n\n<p class=\"wsu-spacing-after--xsmall\">What <em><strong>Do<\/strong><\/em> Worms Eat?<\/p>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>Vegetable and fruit scraps<\/li>\n\n\n\n<li>Coffee grounds and filters<\/li>\n\n\n\n<li>Tea and tea bags (remove any metal)<\/li>\n\n\n\n<li>Egg shells<\/li>\n\n\n\n<li>Paper and cardboard<\/li>\n\n\n\n<li>Bread<\/li>\n<\/ul>\n\n\n\n<p class=\"wsu-spacing-after--small\">What <strong><em>Don\u2019t<\/em><\/strong> Worms Eat?<\/p>\n\n\n\n<ul class=\"wsu-cahnrs_list--green\">\n<li>Meat or dairy products<\/li>\n\n\n\n<li>Fats or oily foods<\/li>\n\n\n\n<li>Citrus or acidic foods<\/li>\n\n\n\n<li>Onions or garlic<\/li>\n\n\n\n<li>Bones<\/li>\n\n\n\n<li>Salty foods<\/li>\n\n\n\n<li>Glossy paper or magazines<\/li>\n\n\n\n<li>Nonbiodegradables (plastics, rubber, glass, etc.)<\/li>\n\n\n\n<li>Pet litter and manure<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Worm Bin Management<\/h4>\n\n\n\n<p>The worm\u2019s body and the bedding should have similar moisture contents, 75 to 90 percent. Add three pounds of water to each pound of dry bedding, a ratio of 3:1. Check the moisture content of bedding by squeezing some in your hand. If a few drops of moisture are released by squeezing, the bedding should have the right amount of moisture. If five or more drops are produced, the bedding is likely too wet.<\/p>\n\n\n\n<p>Keep a four- to six-inch layer of clean bedding on top of your worms and their food. Each new food addition to the worm bin must be placed into or under the bedding. Do not dump the food waste on top of the bedding. It is a good practice to vary the location where waste is buried in the worm box. A worm box two feet wide by two feet long (big enough to handle food scraps from a family of four) has approximately nine locations where kitchen waste can be buried (each corner, in the middle of each side, and in the center of the box). That allows nine feedings before the first location must be used again.<\/p>\n\n\n\n<p>Grinding the scraps is not necessary, because kitchen waste breaks down very quickly. However, eggshells should be pulverized to increase particle surface area and allow for quicker breakdown.<\/p>\n\n\n\n<p>If you are going to be away from home for an extended period of time, feed the worms a little extra and leave them undisturbed. They can go three weeks to a month without feeding. Make arrangements to have someone feed your worms if gone for a longer time.<\/p>\n\n\n\n<p>Worms multiply fast. Avoid overpopulating your bin by periodically removing some worms. Use those \u201cextra\u201d worms to start a new worm box or give them to someone else who is starting a worm composting bin. They can always be added to an outdoor compost pile if a new home cannot be found.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Refresh the Bedding<\/h4>\n\n\n\n<p>It is not necessary to stir or mix the bedding and food\u2014the worms are happy just being fed and left alone. The bedding will begin to disappear after many weeks as worms and microorganisms decompose the material. The bedding will also become darker as it decomposes, making the worm environment less favorable. Large amounts of accumulated castings will become harmful to the worms and the worm population will decrease. Adding fresh bedding should be based on the condition of the bedding and the quantity of worms in the box.<\/p>\n\n\n\n<p>Depending on the amount of room in the worm bin, fresh bedding may be added on top of the old bedding until the compost is harvested. The finished compost will accumulate at the bottom of the worm bin.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Odor and Pest Control<\/h4>\n\n\n\n<p>Odors can be controlled by not overloading the box with food waste, keeping out inappropriate waste, and providing adequate fresh bedding. Start with small amounts of food waste until the worm population is established. Do not add meat, dairy products, or other animal products to worm composting bins.<\/p>\n\n\n\n<p>Vinegar flies can build up in large numbers during warm weather. However, they are more of a nuisance than a serious problem. Keep fruit fly populations low in and around the worm bin by completely covering fresh food waste with several inches of bedding.<\/p>\n\n\n\n<p>Rodents and other animal pests may be a problem if the worm bin is kept outside. Prevent animals from entering a worm bin by keeping the lid securely shut and weighted down or latched. Animal pests will be less attracted if meat and dairy products are kept out.<\/p>\n\n\n\n<h4 class=\"wp-block-heading wsu-spacing-after--small\">Harvesting the Vermicompost<\/h4>\n\n\n\n<p>Remove worm castings and decomposed bedding at least once a year to keep your worms and their environment healthy. The simplest harvest method is to simply move the contents of the worm bin to one side and place fresh bedding and food in the cleared space. Do not add any new food to the old material; place new food only in the new bedding. Wait about a month until the worms have all migrated to the new feeding area and bedding. This will allow you to remove the old material and use it like any other compost.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-compost-in-gardens\">Using Compost in Gardens and Landscapes<\/h2>\n\n\n\n<p>Composts are good soil amendments, providing organic matter and some nutrients (Figure 6). They make the soil easier to work and create a better medium for plant growth. You can mix one to three inches of compost into soil before establishing a new garden or landscape bed. Add smaller amounts (one-half inch to one inch per year) to established gardens. If you are considering adding compost to a site subject to runoff, test soils first to make sure nutrient levels are not excessive. Refer to the Using Compost section under Additional Resources below for background and details on using compost in gardens and landscapes.<\/p>\n\n\n\n<p>Composts applied to the soil surface as garden mulch help conserve water and protect the soil from erosion. The best times to apply compost mulches to annual gardens are in early summer,<br>after plants are established and the soil has warmed, or after harvest in the fall to reduce runoff and erosion. Composts that are rich in nutrients will promote weed growth and are not effective as long-term mulches. Till or dig the compost mulch into the soil when you prepare the garden for the next planting to get further benefits as a soil amendment. For more information on compost use in home gardens, refer to <em>Organic Soil Amendments in Yards and Gardens: How Much Is Enough?<\/em> and <em>A Home Gardener\u2019s Guide to Soils and Fertilizers<\/em> listed in the Further Reading section.<\/p>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-composting-and-environment\">Composting and the Environment<\/h2>\n\n\n\n<p>Composting reduces the flow of waste to landfills or burn piles and produces valuable organic matter for the soil at the same time. Composting does all this using a process fueled by the solar energy captured in plant tissue. These benefits are the same whether you compost in carefully tended hot piles or in cold slow piles. Composting is a simple yet important way to improve communities and the environment.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized wsu-spacing-after--none\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_6.jpg\" alt=\"The sunflowers on the left side of this outdoor garden plot stand nearly twice as high as the sunflowers on the right.\" class=\"wp-image-2659\" width=\"1163\" height=\"872\" srcset=\"https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_6.jpg 900w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_6-300x225.jpg 300w, https:\/\/wpcdn.web.wsu.edu\/extension\/uploads\/sites\/62\/2025\/10\/Fig_6-768x576.jpg 768w\" sizes=\"(max-width: 1163px) 100vw, 1163px\" \/><figcaption class=\"wp-element-caption\">Figure 6. Backyard compost was added to a garden soil deficient in nutrients and organic matter. Sunflowers on left received compost. Sunflowers on right received no amendment. (Photo by Dan Sullivan.)<\/figcaption><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<h2 class=\"wp-block-heading  wsu-heading--style-marked\" id=\"ch6-further-reading\">Further Reading<\/h2>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Making Compost<\/h3>\n\n\n\n<p>University of Missouri Extension. 1993. <a href=\"https:\/\/extension.missouri.edu\/publications\/g6957\" data-type=\"URL\" data-id=\"https:\/\/extension.missouri.edu\/publications\/g6957\" target=\"_blank\" rel=\"noreferrer noopener\">How to Build a Compost Bin (opens in new window)<\/a>. <\/p>\n\n\n\n<p>Sullivan, D.M. 2010. <a href=\"https:\/\/extension.oregonstate.edu\/news\/slow-cool-composting-easy-way\" data-type=\"URL\" data-id=\"https:\/\/extension.oregonstate.edu\/news\/slow-cool-composting-easy-way\" target=\"_blank\" rel=\"noreferrer noopener\">Slow, Cool Composting Is the Easy Way (opens in new window)<\/a>. Oregon State University. <\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Using Compost<\/h3>\n\n\n\n<p>Center for Sustaining Agriculture and Natural Resources. <a href=\"https:\/\/csanr.wsu.edu\/publications-library\/soils-fertility\/compost\/\" data-type=\"URL\" data-id=\"https:\/\/csanr.wsu.edu\/publications-library\/soils-fertility\/compost\/\" target=\"_blank\" rel=\"noreferrer noopener\">Compost (opens in new window)<\/a>. Washington State University. <\/p>\n\n\n\n<p>Cogger, C.G. 2020. <a href=\"https:\/\/pubs.extension.wsu.edu\/a-home-gardeners-guide-to-soils-and-fertilizers-home-garden-series\" data-type=\"URL\" data-id=\"https:\/\/pubs.extension.wsu.edu\/a-home-gardeners-guide-to-soils-and-fertilizers-home-garden-series\" target=\"_blank\" rel=\"noreferrer noopener\">A Home Gardener\u2019s Guide to Soils and Fertilizers (opens in new window)<\/a>. <em>Washington State University Extension Publication<\/em> EM063E.<\/p>\n\n\n\n<p>Cogger, C., and G. Stahnke. 2019 <a href=\"https:\/\/pubs.extension.wsu.edu\/product\/organic-soil-amendments-in-yards-and-gardens-how-much-is-enough-home-garden-series\/\" data-type=\"URL\" data-id=\"https:\/\/pubs.extension.wsu.edu\/product\/organic-soil-amendments-in-yards-and-gardens-how-much-is-enough-home-garden-series\/\" target=\"_blank\" rel=\"noreferrer noopener\">Organic Soil Amendments in Yards and Gardens: How Much Is Enough? (opens in new window)<\/a> <em>Washington State University Extension Publication<\/em> FS123E.<\/p>\n\n\n\n<p>Washington State University Puyallup Organic Farming Systems and Nutrient Management. <a href=\"https:\/\/puyallup.wsu.edu\/soils\/compost\" data-type=\"URL\" data-id=\"https:\/\/puyallup.wsu.edu\/soils\/compost\" target=\"_blank\" rel=\"noreferrer noopener\">Compost and Nutrient Management Overview (opens in new window)<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Food Safety<\/h3>\n\n\n\n<p>US Food and Drug Administration. 2015. <a href=\"https:\/\/www.fda.gov\/food\/food-safety-modernization-act-fsma\/fsma-final-rule-produce-safety\" data-type=\"URL\" data-id=\"https:\/\/www.fda.gov\/food\/food-safety-modernization-act-fsma\/fsma-final-rule-produce-safety\" target=\"_blank\" rel=\"noreferrer noopener\">FSMA Final Rule on Produce Safety (opens in new window)<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Soil Testing<\/h3>\n\n\n\n<p>Fery, M., and E. Murphy. 2018. <a href=\"https:\/\/extension.oregonstate.edu\/catalog\/ec-628-guide-collecting-soil-samples-farms-gardens\" target=\"_blank\" rel=\"noreferrer noopener\">A Guide to Collecting Soil Samples for Farms and Gardens (opens in new window)<\/a>. <em>Oregon State University Extension Publication<\/em> EC 628.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Animal Manure<\/h3>\n\n\n\n<p>Bary, A., C. Cogger, and D. Sullivan. 2016. <a href=\"https:\/\/catalog.extension.oregonstate.edu\/pnw533\" data-type=\"URL\" data-id=\"https:\/\/catalog.extension.oregonstate.edu\/pnw533\" target=\"_blank\" rel=\"noreferrer noopener\">Fertilizing with Manure and Other Organic Amendments (opens in new window)<\/a>. Pacific Northwest Extension Publication PNW 533. Oregon State University. <\/p>\n\n\n\n<p>Clark County Extension. <a href=\"https:\/\/extension.wsu.edu\/clark\/naturalresoures\/smallacreageprogram \/composting-manure-on-your-property\/\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/clark\/naturalresoures\/smallacreageprogram \/composting-manure-on-your-property\/\" target=\"_blank\" rel=\"noreferrer noopener\">Composting Manure on Your Property (opens in new window)<\/a>. Washington State University.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Herbicides and Compost<\/h3>\n\n\n\n<p>Miller, W., and K. Buhl. 2021. <a href=\"https:\/\/extension.oregonstate.edu\/sites\/extd8\/files\/documents\/em9307.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Herbicide-Contaminated Compost and Soil Mix. What You Should Know and What You Can Do about It (links to PDF document)<\/a>. <em>Oregon State University Extension Publication<\/em> EM9307.<\/p>\n\n\n\n<p>Washington State University Puyallup Organic Farming Systems and Nutrient Management. <a href=\"https:\/\/puyallup.wsu.edu\/soils\/clopyralid\/\" data-type=\"URL\" data-id=\"https:\/\/puyallup.wsu.edu\/soils\/clopyralid\/\" target=\"_blank\" rel=\"noreferrer noopener\">Clopyralid in Compost (opens in new window)<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Composting and Weed Seeds<\/h3>\n\n\n\n<p>Zaborski, E. 2010. <a rel=\"noreferrer noopener\" href=\"https:\/\/eorganic.org\/node\/4751\" data-type=\"URL\" data-id=\"https:\/\/eorganic.org\/node\/4751\" target=\"_blank\">Composting to Reduce Weed Seeds and Plant Pathogens (opens in new window)<\/a>. eXtension.<\/p>\n\n\n\n<h3 class=\"wp-block-heading wsu-spacing-after--xxsmall wsu-font-size--xmedium\">Vermicomposting<\/h3>\n\n\n\n<p>Angima, S., M. Noack, and S. Noack. 2011. <a rel=\"noreferrer noopener\" href=\"https:\/\/extension.oregonstate.edu\/catalog\/em-9034-composting-worms\" target=\"_blank\">Composting with Worms (opens in new window)<\/a>. <em>Oregon State University Extension Publication<\/em> EM9034.<\/p>\n\n\n\n<p>Whatcom County Extension. <a rel=\"noreferrer noopener\" href=\"https:\/\/extension.wsu.edu\/whatcom\/hg\/worm-composting\/\" data-type=\"URL\" data-id=\"https:\/\/extension.wsu.edu\/whatcom\/hg\/worm-composting\/\" target=\"_blank\">Worm Composting (opens in new window)<\/a>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n","protected":false},"excerpt":{"rendered":"<p>Craig Cogger, Soil Scientist Emeritus, Department of Crop and Soil Sciences, Washington State University Andy Bary, Senior Scientific Assistant, Puyallup Research and Extension Center, Washington State University Dan Sullivan, Professor Emeritus, Department of Crop and Soil Science, Oregon State University Jim Kropf, Pierce County Extension Director, Agricultural and Natural Resources Unit, Washington State University Introduction [&hellip;]<\/p>\n","protected":false},"author":241,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_wsuwp_accessibility_report":null},"categories":[],"tags":[],"_links":{"self":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages\/786"}],"collection":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/users\/241"}],"replies":[{"embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/comments?post=786"}],"version-history":[{"count":62,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages\/786\/revisions"}],"predecessor-version":[{"id":4875,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/pages\/786\/revisions\/4875"}],"wp:attachment":[{"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/media?parent=786"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/categories?post=786"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/extension.wsu.edu\/pnw-gardeners-handbook\/wp-json\/wp\/v2\/tags?post=786"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}