Does Compost Tea Work?

If you’d like to pick an argument in the mostly staid world of gardening, I can’t think of a better subject than compost tea. I’ve, somewhat cowardly, tried to stay out of the fray and leave the debate to Linda Chalker-Scott and Jeff Lowenfels. If you forced me to pick a side I’d lean towards Chalker-Scott’s skepticism.

Thankfully, I can now point towards the webinar on making and using compost teas that I’ve embedded above. I’ll oversimplify things a bit with a few of my own bullet points inspired by what Dr. Lynne Carpenter-Boggs, Associate Professor of Sustainable and Organic Agriculture at Washington State University and Catherine Crosby, a Ph.D. candidate in Soil Science at Washington State University had to say in the webinar.

  • Due to a lack of research no peer reviewed recommendations can be made on the use of compost tea.
  • Nobody agrees on what compost tea is or how to brew it. What kind of compost do you use? Do you have to aerate it? How and for how long do you aerate it?
  • Compost teas have been shown to both solve and cause disease problems.
  • Compost tea shows promise as a fertilizer.
  • If you add sugar to your tea you need to be very careful about food safety issues.
  • You must dilute compost tea before using.
  • The compost going into tea must be mature and of high quality.
  • You might be better off just applying normal compost to the soil.

My personal conclusions are that if I were a farmer (which I am definitely not), compost tea might be worth looking into as a fertilizer or, in certain specific circumstances, for disease control. As a home gardener, however, I’m going to wait until there is more research before I spend money on a subject that is still so unresolved.

Let us know what you think–leave a comment!

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  1. I’m definitely a skeptic on this one. For the last 45 years I’ve so wanted the promise of organics to be true. Sadly, much of the research is wanting. One of the biggest barriers for me is that many researchers have a vested interest. Much grant $$ have been doled out for organic research over the past 30 years by companies interested in furthering their profitability. Dr. Elaine Ingham did the pioneering work in Compost Teas and her Curriculum Vitae are impressive. However, she makes her living as a consultant, teacher, or public speaker. Rodale’s research is an offshoot of their publishing concerns. Dr. Linda Chalker-Scott would probably prefer to keep her job. And Jeff Lowenfels wants to sell books.

    In the end I think my old botany professor hit the nail on the head: “People who go to so much effort with intricate details, probably are good gardeners and excellent observers to begin with, so of course, their efforts will pay off. It is unclear if it is their perseverance or the methods.”

  2. In my area, you can pick up compost tea for free on certain days at a Hydroponics store. It was a safe way to try out the tea on my plants. I will say, they did better that year and have continued to use it since. Ladybugs came and helped out the plants, when for at least a decade, they never came. By my own home-use, I say it’s worth it to use. I use compost as well, but for a weekly use on the plants, it’s not going to cause harm. Helped my yield at home, as well.

  3. Peace. Used, advocate. Understand some of the confusion. K.I.S.S. brewer. Don’t use it all the time. Actually, rarely. Don’t like criticism. Managing with quality, home made compost for the most part. Open to discuss, not fight.

  4. Being a lazy-ish gardener, myself, I put a spade-full or two of worm humus around plants and let the rain make the tea…

  5. I am a farmer and have used home made compost tea for years with noticeable results. Personally, I don’t understand what all the skepticism is about. Its simply combining a few things proven to work well with the soil (well aged compost, amendments, oxygen, rain water).

    I will say, I do not use it often and only under ideal conditions, which is basically before a spell of overcast days when dew is present. I have to keep an eye on the weather since it takes a day plus to brew. I always see a difference as the plants perk up and become greener. I should also say I tend to play it safe and not add much nitrogen to the mix, which is how I farm in general (too much N leads to pests and less nutrient density). Its no concern to me if I’m not making it the most ideal or efficient way.

    People must be cautious when buying stuff because the gardening world is full of snake oil salesman. DIY compost tea, however, is a no brainer to me and can be done on the cheap and on your own.

    I will say that I think its ridiculous to claim that the promise of organics is wanting. I would say its quite conclusive the promise of industrial and chemical agriculture is what has been lacking and has a lot of payed for research. If you can’t come to that conclusion than you really aren’t trying to that hard or being all that skeptical, just a contrarian.

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