Depending on how you balance the factors of air, water, and the ratio of dry to wet ingredients, compost can take anywhere from a few months to years to mature for use in your garden.

A feature image for a blog post about how you know when compost is done.

So, how do you know when it’s ready?

Learning when to use your compost is one of the many rewarding things about eco-friendly gardening and helping protect the environment.

Signs that Compost Is Ready

One of the most common questions for people who are beginners at composting is, “When will I know it’s ready to use?”

There are some signs that you can look for to guide your decision:

  • Mature compost is dark and crumbly, with a rich earthy smell that isn’t unpleasant or sour.
  • You won’t see any large recognizable pieces of food or organic matter.
  • The heat from “working” is gone out of the pile.
  • The pile is noticeably smaller than when it started.

One trick for checking the compost is to put some in a container and seal it for a few days. If it has a sour or ammonia odor when you open it, leave the pile longer. It isn’t ready.

Also, if you see pieces of twigs or hard things like fruit seeds still visible, but the rest seems ready to use, you can screen it and go ahead.

It’s also recommended that you add the compost to your garden or lawn in the fall. Then, if it does need a bit more time, it can continue working during the winter.

What If the Compost Is Taking Too Long?

Because there are several factors that affect the rate of composting, the finish time can vary considerably.

However, if your pile seems to be working too slowly, check for the following:

  • There is both green (wet) matter and brown (dry) matter.
  • The pile is aerated or you’re turning it often enough.
  • It is moist and humid, but not soggy.
  • The size of the pile isn’t too big. Try to stay under 3 feet by 3 feet.

If you feel confused, talk with someone who is experienced with composting or works in a gardening center. There’s nothing like experienced advice to support an environmentally-friendly lifestyle.

How to Harvest Your Compost

Harvesting your compost mainly means taking the finished product from your bin or pile and transporting it to wherever you need it in the garden.

Generally, the mature compost is at the bottom of the pile, so getting at it will depend on the design of your compost bin or the size of your pile.

Some people use several bins or piles to stagger the maturity time of each. You can work with those that are ready and leave others until later.

How to Use Your Compost

Well-matured compost is an excellent fertilizer for your garden, lawn, herb garden, or houseplants. Use it liberally to improve the quality of the soil and plants.

You can mix the compost into the soil or you can use it on top of the soil. Either way will work well to increase the nutrient content.

To really step up your eco-friendly gardening efforts, collect rainwater to water your garden after you’ve applied your compost. It’s also great for keeping the compost pile moist.

Knowing when your compost is ready is one of the many pieces of knowledge you’ll acquire as you embark on your eco-friendly gardening journey.

12 thoughts on “How Do You Know When Compost Is Done?”

  1. This is a very practical post and full of great tips.

    Thanks for the tip to check if compost ready by placing it in a sealed container bag for a few days and then check it by its smell.

    I also like the idea that if you put it in your garden at the beginning of winter then if it isn’t quite ready, it has all winter to finish it’s process.

    Thanks for sharing.

    1. Yes, a finished product is best for use in the garden, and you’ll get used to judging that as time goes on and you learn the process by experience. Plus, in the beginning, you can also ask someone who already works with compost to have a look and check it for you.

  2. Hi, I’ve just gone through your article on “How do you know when compost is done?” I find it very educative and informative. I definitely agree with you that learning when to use compost is actually one of the rewarding things about eco-friendly gardening and helping protect the environment. One important thing I never realized is that the compost heap will become noticeably smaller when it is ready for use. Thank you for sharing such helpful information with us. I promise I will be sharing it further too.

  3. Well, I did not know you could cook waste like this. Very interesting. I used to garden many years ago but never used compost or knew the process of making it. I will share this post with my daughter. She has started homeschooling my grandson during the lockdown and they made a miniature garden as a project. Teaching him how to make compost would make an excellent lesson. Thank you. 

    1. Yes, that would be a wonderful way to expand the lessons on gardening and caring for the environment. It also teaches self-sufficiency.

  4. This is such a wonderful article! I’ve always wanted to own a place with a small garden and to start composting but I’ve never been sure exactly where to start. This article and your composting for beginners article is an absolutely perfect place to start. I’ll definitely be looking more into your tips when then time comes for me to start doing this on my own.

    1. That’s an awesome goal to aim for. You’ll benefit yourself and the environment at the same time, which really benefits everyone. I hope it goes well for you. As you get used to composting, you’ll gain experience and understand how the process works best in your gardening plan.

  5. Hi Stella,

    I’m glad I stumbled on your article. I have long been wanting to do research on how to compost but I was not able to give it time and dedication.

    Two years ago, I tried making compost in a pail. But with no knowledge, I kept adding our biodegradable scraps to the pail. The result was a disaster instead of fertilizer.

    Thank you for mentioning the ratio, the need for turning and aerating, and aging. I like the way you discussed signs for if the pile is done, what makes it mature too long, how to harvest, and how to use it.

    I started to plant herbs in our garden and I was buying fertilizer. I think I can do it right now with what I have learned from you today

    Thanks for sharing this eco-friendly information!

    Rose

  6. I was wondering why it sometimes took a long time and sometimes it was fast. I think it all has to do with temperature. The types of microbes working within a pile will determine the speed of the composting process: some work fast at higher temperatures and some work more slowly. This is the difference between hot and cold compost.

    1. Interesting observations. Yes, there are several factors that influence how long it takes for compost to “cook.” Once you learn the basics and gain experience with your own compost pile, you’re better able to judge the process. With compost, “doing” is definitely the best teacher.

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