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Compost Tea: Does It Work, or Not?

This photo, supplied by Dan Corum at the Seattle Zoo, shows the rose gardens that are tended solely with compost tea.

This photo, supplied by Dan Corum at the Seattle Zoo, shows the rose gardens that are tended solely with compost tea.


I’ve long told the story of my Grandmother, Clarida Van Dyne, and her “manure” tea that she made on her dairy farm in Bradford, Maine. In recent years, as I’ve espoused the virtues of applying compost tea to the landscape to add valuable micronutrients and, most importantly, microbial life to the soil, I’ve had all sorts of feedback. Good and bad.

The official word from Cornell University, for example, is that compost tea doesn’t work. When it has measured disease suppression or the addition of “life” to the soil in terms of increase fungal or bacterial content, the illustrious New York institution insists that compost tea is bunk. Here is a passage from a 2007 article in the New York Times by Leslie Land, in which she pitted my “opinion” against that of Dr. Frank Rossi of Cornell.

To put this into context, Ms. Land was asking me how to hasten the transition from synthetic chemicals to organic solutions:

Asked if there was a way to speed things up, Mr. Tukey suggested compost tea. Applied monthly to a lawn that is also fed with organic fertilizers, it can reduce transition time to one season, he said, adding that compost tea ”is like a blood transfusion for the lawn.”

Frank S. Rossi, a turf specialist at Cornell University and a nationally recognized expert on golf course maintenance, does not share Mr. Tukey’s enthusiasm. Dr. Rossi’s research lab has evaluated compost tea’s effect on turf and found little proof of a major benefit.

And so those of us who see the results with our own eyes are left to scratch our heads, and even make a joke or two about it.

My friend, Sandy Syberg, of Purple Cow Organics in Wisconsin, told me he was heading off to California for a week of compost tea trials. “Haven’t you heard?” I asked. “Compost tea doesn’t work!”

We both shared a good laugh, but the serious question remains. Does compost tea really work?

The issue, of course, is that all compost tea is not created equally. In fact, there are probably as many variations in compost tea as there are variations in gardeners. Most essential is the quality of the compost from which the tea will be brewed. Then comes the addition of air to the brewing process, or the “feeding” of a food source such as molasses to the final mix. How much air to add? How much molasses to add? At what temperature?

It’s not all that different than brewing beer, and if you live in a state like Maine where I do, you know that dozens of different microbreweries churn out hundreds of different styles of beer that all taste differently — and all leave you feeling a bit differently both as you’re drinking, and when you wake up the next morning.

The bottom line is that the pros — the Elaine Inghams and Betsy Rosses of the world — have the compost tea literally dialed in. To even suggest that the application of their teas has no value is flat-out preposterous.

But will the tea you brew in your own five-gallon bucket have any value? Maybe. Maybe not. I have met hundreds of gardeners who swear by it and a few who don’t see the point. The good news is that it’s inexpensive, practically free, to make. And it really won’t do any harm, provided it doesn’t smell pungent or like ammonia when it’s applied. Good compost tea, like good compost, should have a sweet earthy smell. You can check out the compost tea video on the SafeLawns site:

As for the teas you can buy at the garden center, you should ask the “fresh” question. If the tea has been capped for any period of time, the only thing living in the jugged tea will be bacteria. Fresh tea can be full of a whole rainbow of microorganisms and is definitely more likely to have a positive impact to your lawn, garden, trees or shrubs.

What’s your experience with compost tea? What pointers do you have, or comments — pro or con — to add to the debate? I’d love to hear them.

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

Number of Entries : 1023
  • Marnie Vyff

    When it comes to growing, healthy, regenerative soil is vital. Organic is the only method of growing that is sustainable. An estimated 10,000 species of microbes,
    including bacteria, fungi, and nematodes live within a gram of organic soil. The plant eats the nutrients in the soil and all the microbes help replenish the nutrients. Conventional farming practices have, in essence, killed the beneficial life cycle in the soil with the use of pesticides. The pesticides kill the beneficial microbes as well as the pests, and throw off the natural balance. The pests rebound faster with nothing to keep them in check. We then have to use more pesticides, killing the soil even more. Each year, the soil gets more and more depleted rather than richer. We then have to use fertilizers to replace the nutrients. The inorganic firtilizers are derived from petroleum products and the cost is much higher to produce them, than just letting nature do her business. The array of nutrients is not complete either. Its like people living on bread alone. From destroying healthy soil, not regenerating it, and erosion, we now have 25% of the topsoil left in America from before the industrial age. It takes at least three years for soil to get back into its normal nutrient cycles.

  • Greg Gutknecht

    I have been using compost tea in my business for 6 years now. I often wonder why no one else is using it because of the success I have had with it. You mentioned in the beginning of your post about manure tea. I think it would help others to understand that there is a difference between manure tea and compost tea. Highly aerated compost tea is quite different from a manure tea and produces very different results. I think it would help others if you could elaborate a bit more on those differences for us.

    • Paul Tukey

      You are absolutely right. The manure tea that my grandmother made on the farm was more of a manure “stew.” Professionals now refer to good compost tea as “actively aerated,” meaning oxygen has been applied. Teas can also be enhanced with worm castings, kelp, humic acids, biochar . . . all sorts of other amendments. As this thread progresses, my hope is that others will share a few trade “secrets.” How about you?

  • Bob Posthuma

    Hi Paul,

    Have you or any of your readers seen the recent TV segment of “Ask This Old House” where they interviewed the grounds manager of Harvard University? Harvard is very impressed with compost tea, here is a link to the video.

  • Barefoot James

    We debate this all the time on – organic forum. Come on over and learn. AACT is a big part of my toolbox. We use lots or humus/humates from NM, Mycorrhizae, compost top dressings, worm casts, a little kelp/seaweed and thousands of gallons of AACT. My business was built on it and yes it works very well. But I will say CT is just one tool I use and if you continue to use broadcast apps of herbs/pests and fungicides your results will probably not be realized – sort of like a smoker trying to recover from a knee replacement. Needs more time.

  • windee

    I moved to western North Carolina four years ago. I make my living as a garden designer and many of my clients houses (mine also) are built on clay subsoil because of the mountain terrain. The first two years I really struggled with not only growing healthy grass but trees shrubs perennials etc. We had applied mountains of mushroom compost but plants were still not responding the way I thought they should. I got inspired by Pauls book and we started making tea on a small scale for my own house and the trouble spots in my clients gardens. Voila, by the end of the season you could visibly see the switch in health of the grass and other plants. Most plants had moved from a state of existence to thriving. Areas that had not responded were treated the next season with excellent results.
    Grandma knew what she was talking about!
    Thanks Paul.

    • Paul Tukey

      Great post, Windee! OF COURSE my grandmother knew what she was talking about.

  • Pingback: Does Compost Tea Work? A View From the Post | Safelawns Daily Post and Q&A Blog

  • Pingback: Compost Tea: Resources for Brewing Your Own | Safelawns Daily Post and Q&A Blog

  • doakdork

    Compost tea
    is probably a useful thing. But the matter is that it takes a lot of time to be
    prepared and nobody knows what kind of bacteria and funguses he grows. Together
    with useful bacteria there can live harmful fungi and other plant diseases in
    your compost. Instead of it you can take already done and guaranteed
    microorganisms which will work in the soil and on plants as fungicides and
    insecticides. Any harm, any lost time, any equipment. The whole you need is the
    biological preparation and water. To be sure visit the page Believe me you’ve
    never seen something better.

  • thoomfoote

    I make and use it but it is not free. The labor involved in distributing a 50 gal batch of tea in 5 gal buckets to my 1 acre fenced garden is significant and expensive if I put a $ figure to it. As soon as it is done I have to dedicate a day to getting rid of it. The opportunity cost of this is substantial when I have 50 other competing tasks needing to be addressed. I believe it is worth it but it is definitely NOT almost free.

  • The Rhizome Cowboy

    When I made my first compost tea, I wondered what kind of water to use. Because I was afraid that the chlorine in tap water would kill the microorganisms that I am trying to grow, I used bottled spring water. I saved the empty 3-liter bottles for other uses.

    For my first tea, I also used an inexpensive battery-operated aquarium pump, but it died after 112 hours of operation–before I felt that the tea was ready. However, I applied the tea anyway. For my next tea, I plan to replace that bad receptacle on my patio and use a plug-in aquarium pump of a different brand.

    Although I like Paul’s idea of using a siphon attachment to draw the tea from a bucket, I use an adjustable-rate hose-end sprayer with a one-quart bottle so that I can apply 1 qt. per 1000 sq. ft.

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