Episode Details

In today’s Beyond the Basics podcast (above), we talk with Ralph Morini, Virginia Cooperative Extension Master Gardener and researcher about his compost tea article for the Piedmont Master Gardener’s newsletter, The Garden Shed. The March 2019 article is entitled, “The Truth About Compost Tea: Making It, Using It, and What To Expect From It”. Read it for yourself for even more information about the Compost Tea-making process.

In that article, Morini delved into the online compost tea rabbit hole, which is comprised of the deep warrens of compost tea opinion, experience, sales attempts, and a smattering of actual well-researched studies. As you can surmise from our conversation in today’s newsletter podcast, Morini came away from his deep dive with more questions than answers. Which harkens back to Farmer Fred Garden Rule #8: “If It Works for You, Fine. But Keep an Open Mind.” Morini concludes his article with nine sources of reputable information, source material you may want to check out for yourself.

The genesis for our thorough discussion regarding the “truth vs. myth” aspects of compost tea use sprung from a comment Steve Zien, an organic gardening professional, made about using compost tea back in Episode 188. He loves it. Especially using worm castings as the basis of your compost tea.

I’ve know Steve for 40 years. I know that he is usually ahead of the curve when it comes to implementing his earth-friendly garden practices. I also know that the rest of us usually catch up with him and buy into his train of thought about a decade later. It turns out, he’s usually right.

Here are the Cliff Notes version of our discussion with Ralph Morini. Points about compost tea that you should consider before you apply it around or on top of your plants:

How the Compost Tea is Made

Ralph Morini:

“Compost tea is a solution made from compost and clean water* combined in a bucket or some sort of a container. We recommend that the solution be aerated. As Steve mentioned, the best way to do that is with an aquarium pump. Let it run for one to two days. The typical aquarium aeration system includes a pump that sits outside the aquarium and then basically a couple of diffusers, the air from the pump will go into an inlet on what's called a stone and it becomes diffused at the output side of the stone and blows bubbles into the water.”

*Ah yes, the water quality. Garbage in, garbage out. That might have been the problem for some of the studies of compost tea. Your water may kill the beneficial bacteria and fungi that you are attempting to add to the soil. More on that below.

What is the Active Ingredient in Compost Tea?

Ralph Morini:

“What it does is it allows the microbes in the compost to multiply many, many times over so that you have an extremely microbe rich solution, a solution that advocates claim can be used for anything from fertilization - which I'm not buying - to enriching the microbe content in the soil, which is what Steve referred to. And if you have enough organic matter in the soil to feed them, it can release a lot of the nutrients that matter is holding in the soil. Some people use it as a foliar spray, which, if you have the right type of microbes in the solution, can help to prevent disease by out competing; or, the good guys somehow overtake the bad guys and reduce disease damage on your plants. Or you can use it to stoke up your compost pile. If yo