We often think of compost as a nutrient source, but one of its most important functions is actually breeding beneficial microbes.
Then we can multiply these microbes even further by brewing up some aerated compost tea.
Properly aerated compost tea is one of the most effective ways to promote health and prevent disease in our gardens, resulting in healthier plants, tastier food, bigger flowers, and heavier yields.
When to use
Compost tea is helpful anytime, but especially in particular circumstances and at certain times of year.
It’s most effective if applied when the conditions are good for microbial activity – whenever it’s warm enough and moist enough.
Spring and fall are usually the best times, though applying it every couple of weeks throughout the growing season is certainly great, too.
Early morning and evening are the best times of day for application, to avoid killing the microbes with UV from the sun.
You’ll need a brewer. You can make your own, using a strong aquarium bubbler and a bucket.
The bubbler needs to move a fair amount to keep your compost tea properly aerated and avoid breeding anaerobic microbes that produce toxins.
Or you can buy a compost tea brewer whose airflow is accurately calibrated to its volume.
First, you need good quality compost.
If you’re confident your own compost has the right microbial balance to spread in your garden, you can use your own.
Otherwise, my compost tea brew kits come with a supply of high quality compost to get you started.
Obviously, you’ll need water. Rainwater or well water is ideal, because unlike municipal water it’s free of bacteria-killing chlorine and chloramine.
But if tap water is your best option, you can let it stand overnight or run it through the brewer for 15 minutes before adding compost.
A small amount of humic acid added to your cauldron also helps neutralize the chloramine, if that’s present in your municipal water like it is in Victoria.
Your microbes will need some food in order to multiply. Unsulphured organic molasses, rock dust, liquid kelp, and sea minerals provide a rich diet for your bacteria as they multiply.
Getting into action
Once your cauldron of mystery is full, aerate the tea for 24 to 72 hours – usually no longer, as the microbes will start to die off once they’ve used up their food supply.
Apply it to your garden immediately, letting it sit no longer than 4 hours if possible, while the microbes are most active.
I use it primarily for spraying right onto leaves. It’s best to leave it undiluted for these foliar applications.
You can use a backpack sprayer, a hose-end sprayer with a pump, or just some good old hand pumping action to apply your compost tea to plant leaves at a rate of 1/2 litre per 1,000 square feet. The less filters the microbes have to go through, the better.
Compost tea is so effective because it’s part of a winning strategy – managing our gardens for health, instead of being in a constant reactive battle with disease. Surrounded by friendly microbes, our plants will thrive.