The Compost Tea Garden Growth Experiment – Does It Work?

Garden — By on September 30, 2013 6:00 am

Compost Tea Experiment Haven Brand Compost Tea

Organic soil amendments  for your garden and garden containers can be confusing.  Although I have tried hundreds of products in my test gardens before, I have never regularly used compost tea as a soil conditioner. I went to my good friend Annie Haven, who sells the well known Haven Brand Manure Tea, and asked her if I could conduct an experiment with her tea to see how it might work in my garden. After all, I have always been a strong believer in manure as a soil amendment, and it is about time I tried soil conditioning with it as well.

Compost Tea Experiment Start of Growth

The Experiment:

A. What was the same in each container -

In order to make this a fair experiment, I placed the exact soil combination in each container. I used one-half rotted composted manure, one-half Organic Mechanics Potting Soil, and 3 Tablespoons Actino-Iron Soil Amendment.

Each container held 3 plants;

  1. Bonnie Plants Rosemary
  2. Purple Flash Ornamental Pepper
  3. Superbells Pomegranate Punch Calibrachoa

These three plants were measured and were the same height with similar root structure and size. I even cut the calibrachoa so that the height would be the same. In other words, each container held soil and plants that were near exact to their neighbors (see above photo which shows the first week of experiment).

B. What was different in each container -

  1. Container #1 had 1/3 of a Jobes Organic Spike placed in the middle of the container between the plant roots. It was watered once per week.
  2. Container #2 was watered once per week like the others, however, it was watered with Haven Brand Manure Tea once per week while the others were just given water.
  3. Container #3 had nothing additional whatsoever given to it and was watered once per week.

Compost Tea Experiment Rain Water

How To Make Compost Tea:

Compost tea, when brewed, will look like the liquid you see in the bucket in the above photo. I typically put one manure tea bag in for one bucket or Compost Tea Experiment Brewing the Tea with Rainwaterwatering can of water. I add rainwater from my rain barrels. Let it steep until a dark brown color.

DO NOT DRINK – this tea is made from manure and is only to be used as a soil conditioner for your plants.

Water your plants with the tea and be sure sprinkle on the leaves as most experts say it is also absorbed through the leaf system as well as through the soil.

The Experiment Results:

Below you see photos of the growing progress. You can see that the container #1 definitely has a stronger green color, more growth and more flowers as the season progresses. This is because the fertilizer spike is different than a soil conditioner. It has 3% Nitrogen, 5% Phosphate, and 3% Potash.

Manure tea has strengths as well – manure tea’s are known to have micro-nutrients that help build up the organic content of the soil. By improving a soils structure you increase its ability to hold and release nutrients – you also increase the root structure of plants.

June Results

Compost Tea Experiment in June

July Results

Compost Tea Experiment in July

Early August Results

Compost Tea Experiment in August

In early August  I measured the results in inches. #1 had the fullest, greenest, plants. However, #2 had the tallest rosemary and placed second in flower and pepper production. #3 did not perform as well and produced less flowers, but it was alive still as long as it was watered regularly. I think #3 did as well as it did for the first few months because of the soil planting mix I used, but petered off towards the end of the season without a regular amendment source.

Late August Results – SURPRISE!!!

Compost Tea Experiment Drought Situation

By late August I was out of town and away from my plants for several weeks, so everything got watered except the manure tea experiment. I forgot to water for two weeks – OH NO! So when my daughter went out to water for me, I was very surprised when she came back in running and shouting, “You HAVE to see the MOO POO TEA experiment! Bring a camera! HURRY It’s a miracle!!!” So we ran out and looked at the experiment. That is when we discovered a big surprise – both #1 and #3 have sagged and browned considerably (see photo above). They really had a rough few weeks without the regular watering. But the plants in #2 – the manure tea container – were not sagging, had not dried, and looked almost exactly as they had before.

My daughter said, “Why does the moo poo tea plant look like it has not been through a drought while the others look like they have been? They are all crispy!”

An obvious answer to that question is that the root systems in the manure tea’d plant grew “hairier roots”. More roots on the base of the plant enables plants to have the ability to take up more nutrients and become FTC Disclaimerstronger based on the weekly manure tea amendments.

The Final Determination

Manure tea did not seem to help the plant over-produce ridiculous quantities of flowers, but what it did do was strengthen the root systems enabling the plant to survive drought better than the other containers. It also contributed as a fertilizer for the plant, enabling it to place second in flower and pepper production compared to the plant that had no soil amendments at all.

My daughter and I have determined this growing experiment a success – it has shown us that manure tea as a soil amendment works for our garden. We will use it next year in all our containers and wall gardens.

Special thanks to Annie from Haven Brand Manure Tea for allowing us to use her Moo Poo Tea, and to all the plant and soil amendment contributors for helping make our experiment a success!




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  1. Tom Mann says:

    Great experiment, Shawna! Although I’m a regular user of Annie’s Manure Teas and can see a lot of differences from years past, I’ve never tried side-by-side comparisons before. Might be something I might play with this fall/winter, now that we’re entering the Pansy/Viola and Fall veggie season. Thanks for sharing your results. ~ Tom

  2. Kerry says:

    Great experiment, Shawna. I wonder if using something like a Jobe’s Organics food, along with the Moo Poo would get you stronger roots and max flowers too? Might be a perfect combo.

  3. Great info and story, Shawna. Thanks for sharing with us. I may look into the Jobe’s Organics also, as suggested by Kerry.

  4. Thanks for sharing this test. Quit a different and great for Moopoo from Annie Haven. We will use your story in Holland.

  5. David says:

    Great experiment! Did you examine the roots? Pictures of that would be cool too!

  6. Segra says:

    Fantastic, not what I thought would happen at all. After I saw this I decided to try this in my fall Lettuce beds and see where it goes! I will keep you posted you clever woman you.

  7. Robert Pavlis says:

    There are a number of statements above that are incorrect.
    “manure tea’s are known to have micro-nutrients that help build up the organic content of the soil. By improving a soils structure you increase its ability to hold and release nutrients”

    Micro-nutrients will not build up organic content. Besides without a proper test you have no idea what if any micro-nutrients were added from the tea.
    Neither micro-nutrients nor organic content alone will build soil structure in the short term of one summer in a pot.

    “An obvious answer to that question is that the root systems in the manure tea’d plant grew “hairier roots”.” This answer is not obvious. Your trials did not show any evidence that the tea’d roots were hairier nor that the total root mass was larger. It is just as likely that the #2 can got more water – a variable that was not controlled in the experiment.

    “most experts say it is also absorbed through the leaf system”. In fact experts know that very little nutrients are absorbed through the leaves.

    “it has shown us that manure tea as a soil amendment works for our garden”. You can’t make this statement based on your trial. What happens in a pot of artificial soil can have little relationship to what happens in the ground.

    It is good to see people doing such trials, but the results have to be analyzed properly and scientifically. There is little scientific evidence that manure teas work, and there is evidence that they can be harmful in a garden. The experts, ie scientists, do not recommend manure tea.

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  8. Lily says:

    Wonderful experiment! Thank you, for conducting and sharing! I often wonder about what people think works best but seeing the true results is really eye opening!

  9. Lyndsay says:

    What a great experiment! Everyone is curious whether compost tea measures up to conventional fertilizer, but there’s the proof! If you do it carefully, you can also use soil conditioners in combination with fertilizer to really increase your plant growth.

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