Updated: Sep 20, 2022
As an organic and regenerative gardener, I choose to fertilize my soil (remember, feed your soil, and your soil will feed your plants) with natural fertilizers. My favorite soil feeds I like to brew are Compost Tea, Vermicompost Tea, Comfrey Tea and Insect Frass Tea.
Let's look at the benefits of each and how I brew them.
I make my own compost using the hot composting method and once I have finished compost I like to make compost tea to feed my soil. Using compost tea results in a more rapid benefit to the soil as it can take a top dressing of compost up to 6 months to reach the rhizosphere (root zone).
Materials needed: 5 gallon bucket, unchlorinater water, 4 cups of compost, a food source for the microbes (uncultured molasses, fish/seaweed emulsion, rice flour) and aeration. Aeration is critical to keep the microbes alive. I use two bubblers to make sure the microbes have enough oxygen to multiply and stay alive.
I add a food source for the microbes to keep them happy and reproducing. I use unsulfured molasses, fish/seaweed emulsion or rice flour.
The tea needs to brew for 24-48 hours, and I make sure to keep it out of the sun as UV rays will kill the microbes. If you are going to be using your compost tea as a foliar spray, make sure to put the compost into mesh bags so that you will not have to strain it when it's done brewing. Again, when you spray the compost tea on your plants, make sure to do it early morning or evening as the UV rays will kill the microbes you just sprayed.
A great thing about compost tea is that you cannot apply too much too often. It will not burn your plants and the microbes in your soil will come to a natural balance.
Worm tea is similar to compost tea, but made with worm castings (poop) instead of regular compost.
Like compost tea, you don't have to worry about over-doing it with worm tea. You can dilute it and use as a foliar spray or root drench. Just remember to use mesh bags for the worm castings when you brew the tea so you don't have to strain it and you won't' clog your sprayer.
Comfrey tea offers your plants a Potassium and Phosphorus boost which is good for plants that fruit and flower.
Comfrey tea is easy to make. It's a set it and forget it type situation. Cut up comfrey leaves into a five gallon bucket, fill the bucket with water, put on a lid and let sit for two weeks. Disclaimer: Comfrey tea smells terrible. It rivals fish/seaweed emulsion for stink factor.
I apply comfrey tea as a root drench and just let any pieces of leaves dump out on the soil surface and stay there to further decompose.
Second Disclaimer: Many people dilute their comfrey tea in fear of burning the roots. I am experimenting with whether this is in fact true or not, so you may see me use it undiluted. Do your own research, and do what makes you comfortable.
Insect Frass Tea
The easiest and fastest tea I make is insect frass tea. It takes less than a minute to mix up and can be applied immediately. Insect Frass can be used every 2-4 weeks.
A great alternative to smelly fish/emulsion for fertilizing seedlings is insect frass tea. Mix 1/2 cup to a gallon of water and apply within two hours of mixing it. Insect frass has an NPK of 3-2-1 which is perfect for seedlings but also for feeding the microbes in your soil. Microbes prefer low NPK numbers, so anything above 10-10-10 is too much for them.
Source: "Teaming with Microbes" by Jeff Lowenfels and Wayne Lewis