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Actively Aerated Compost Tea

Aerator, molasses, a paint strainer full of compost and a bucket of water.
Aerator, molasses, a paint strainer full of compost and a bucket of water.

There are many teas for the garden.  Manure tea is made by steeping… you guessed it… well-aged manure in water for several days.  Well-aged is the key.  Many years ago I gathered horse manure, made a tea and righteously spread it – and all the Bermuda grass seed that was in it – all over my vegetable garden.  I’m still battling the grass.  With fresh manure you are also brewing some nasty bacteria with which you really shouldn’t be dealing.  Allowing well aged or composted manure to brew for a couple of days will produce a nice nutrient tea for your plants.  There are better brews for your effort.

Plain compost tea is when you take samples of good soil and allow them to steep in water for several days and use that.  This brew has some microbes and basic nutrients in it and is better than plain water for enhancing your soil and as a foliar spray.

However there is a super brew called actively aerated compost tea.  It is very simple and inexpensive to make and it works wonders.  There are many recipes for it, depending upon how analytical you want to become.  Studying your soil under a microscope and following the advice of Dr. Elaine Ingham will give you the premium tea for your particular soil.  Dr. Ingham and Dr. Carole Ann Rollins have many books out on the subject of microorganismsin the soil which are all fascinating and well worth the read; if you ever have the chance to hear Dr. Ingham speak, take it!

I don’t tinker with my tea at this time because I just don’t have the time for it.  You may not, either.  So this is the basic aerated compost tea recipe that will revitalize your soil:

You will need a 5-gallon bucket, a paint strainer or cheesecloth or an old sock, a fish tank aerator or air bubbler, and one or all of these: organic unsulphered molasses, organic flours, organic corn meal, kelp.  I have had excellent luck with TeaLab’s Bubblesnake Compost Tea Brewer.  I don’t get anything for the plug, I just found that the kit really works and is easy to buy.  I purchased through AmazonSmile.

Fill the bucket with either rainwater or tapwater that has stood for at least a day for the chlorine to have evaporated.

Take the paint strainer or sock and fill it with samples of good soil from around your property.  If you don’t have any good soil, then add the best you have and then take good soil from areas as close to your property as possible.  If you will be using the tea on bushes and trees, then be sure to take soil from under the same.  Woody plants  like highly fungal soil.  If you will be using the tea for annuals and veggies, then go heavy on fine, well-composted soil that is bacteria-rich.  Do the best you can; you can’t go wrong unless you take soil that has been sprayed with chemicals, use treated wood chips, or anaerobic soil (you’ll smell it if you do).

Tie the top of the cloth and put it into the bucket.  You may tie twine or something around it so that you can haul it out of the bucket if you’d like.  This is important on larger containers, but not so much with the small bucket.

Place the aerator or bubbler in the bucket, making sure the air intake hose is clear, and plug it in.

Add about a half tablespoon of molasses.  It is important that the molasses is unsulphered and organic for the same reasons that the water shouldn’t have chlorine in it or the soil any chemicals: those things will hurt the microbes that you will be growing.  For growth of other microbes, add about a teaspoon of any or all of the following: organic cornmeal, organic wheat flour, liquid kelp, and if you have it tucked away in your shed, bonemeal and bloodmeal (otherwise don’t buy it specially!). So the more different foods you add, the less of each that you use. Two tablespoons of food is about all you want; don’t have a big glob of it floating in your bucket.

Allow the aerator to do its thing for about 13 hours. When its done it should look and smell like sweet tea.  Use it within a couple of hours or the creatures will use up all the oxygen and it will go bad.  There is much discussion about how long you brew it, etc., just as there are hundreds of stew recipes.  This is the recipe taught me in my PDC and one I’ve heard elsewhere.  If your tea smells bad, any hint of ammonia or ‘off’ smells, don’t apply it to your plants.  You’ll be hurting them.  Be sure you have good compost, fresh water and proper aeration, and don’t let it sit too long.

What you are making is not just tea, it is soil inoculant.  The micororganisms in the compost will feed on the molasses and oxygen, reproducing until at about 13 hours their numbers will peak and begin dying off a little.  The tea should be used within a couple of hours.

Brew the tea for 13 hours then gently apply as a soil drench or foliar spray.
Brew the tea for 13 hours then gently apply as a soil drench or foliar spray.

What this tea is doing when applied, is establishing or boosting the fungus, bacteria, amoebas, nematodes, and other soil inhabitants in your dirt, all of which are native to your particular area.  If you have decent soil already, then you can use this tea 1:10 parts dechlorinated water.  If you have rotten dirt, use it straight along with a topping of compost.  Compost, whether it be cooked composed compost, straight leaf matter, shredded wood, logs, damp cardboard or natural fabrics, all provide shelter and hold moisture in so that your microbes have habitat.  Compost, of course, is the best source of food, moisture and shelter for them.

Apply the tea with a watering can, or a sprayer that has a large opening for the nozzle if you are using the tea as a foliar spray.  A squeeze-trigger bottle used for misting has too narrow an opening and will kill a lot of the little guys you have just grown.

Using the tea as a foliar spray will treat disease, fungus and nutrient deficiencies, and help protect plants against insect attack.  Instead of spraying sulfur or Bordeaux solution on your trees as is preached by modern gardening books, use compost tea on the leaves and around the drip line. When applied to leaves, the plant’s exudates hold the beneficial microorganisms to the stomata or breathing holes protecting them from disease and many harmful insects. You can’t overdose with compost tea.

All the additives that are recommended to ‘improve’ your soil are bandages not solutions.  Think of the billions of soft-bodied creatures living in your soil, waiting for organic matter to eat.  Then think of the lime, the rock dusts, the gypsum, the sulfur, the NPK concentrated chemical fertilizers (even derived from organic sources), poured onto these creatures.  It burns them, suffocates them and kills them.  Your plants show some positive results to begin with because they’ve just received a dose of nutrients, both from what you applied and from the dead bodies of all those murdered microbes.  However the problem still is there.  The only long-term solution to locked-up nutrients in the soil, hard pan, heavy clay, sand, compaction, burned, or poisoned soil, is good microbe-filled compost.  Remember that microbes turn soil into a neutral pH, and allow more collection of neutral pH rainwater.  Nutrients in the soil all become available at a neutral pH; there is no such thing as an iron-deficient soil.  The nutrients are just locked away from the roots because of the lack of microbes and the pH.

There are compost tea brewers of all sizes, and lots of discussion about how well they work and whether they actually kill off a lot of microbes.  See Dr. Elaine Ingham’s work for discussion on different brewers.  For large scale operations there are large tanks with aggressive aerators, and the tea is sprayed from the tanks from a truck bed directly on the fields.  If you can’t compost your entire property, then spraying compost tea is the next best thing.

If you’d like to be more involved with the biology of your tea, see Qualitative Assessment of Microorganisms by Dr. Elaine Ingham and Dr. Carole Ann Rollins.  This book has photos of different soil components as they appear under a microscope, identifying and explaining them.  By studying your soil’s balance through a microscope and then tweaking your tea to compensate you’ll be making the most powerful soil inoculant you can.



  • Christopher

    Well an udated “fashionable” website draws more readers. If a reader sees your website is outdated (“unfashionable”), he/she is likely to click around and find a new one. Perhaps this isn’t important to you either. Either way, the blue background makes it hard to read so it should be white 🙂

  • Diane

    Hi Christopher! Thank you for visiting my blog. Sorry that the color bothers you. I’ve been thinking that its time to revamp the page anyway, so I’ll keep your advice in mind. Others have commented that they like the color, but I can see your point. I don’t care about being fashionable; I just like blue. I’ll work on it soon. Thanks again! Diane

  • Christopher

    Can you change the background color on your site to white. It’s so hard to read with the blue background that I can’t stand it, but the information is valuable I would love to be able to read it. I think others visiting your site would appreciate a white background as well. Also, the blue is a bit 90’s. Thanks!

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