Worm Casting Tea Supplement

by Mary
(Redmond, OR)

I have a worm factory; it has been in use for about 3 months; can I use these composted castings for fresh worm tea for my plants? A local dealer told me it was not a good idea because of all the bacteria, as I have an aeroponic system, and says it would kill the roots and introduce "bad" bacteria into my system.

I would like to stay with organic feeding for both the veg stage and flower stage.

Also with worm tea and sea kelp, would you need to add any other additives to enhance the flower and fruiting stage.

Thank you, Mary

Answer: Mary- my personal opinion is that this dealer doesn't know what he is talking about. One of the main sources of nutrients found in soil is from worm castings. The micro-flora in the gut of worms adds a whole host of beneficial micro-organisms and amino acids to the soil as worms produce castings.

Plants have evolved over millions of years to flourish (in a symbiotic relationship) by using the waste products of worms and millions of beneficial micro-organisms found in the soil. Later, when the plant dies, the worms and micro-organisms consume and decompose the plant material turning it back into Nitrogen, Carbon, humic acids, and amino acids (which other plants will again use).

Beneficial micro-organisms and worms are key to producing nutrient rich compost....the living soil that is the keystone of organic gardening. Before the 1950's, every farmer was an organic farmer....it was only after WW2 that large corporations took massive chemical stockpiles used to produce munitions and began packaging and selling them as chemical fertilizers and pesticides (giving birth to "modern" agriculture).

Unfortunately, the huge profits made from the war were poured into advertising and marketing campaigns to advance this new money making venture. Fast-forward to today, many people are brainwashed and believe that you cannot grow a successful garden without chemical fertilizers and/or toxic pesticides. The truth has become so mangled and twisted that some will even claim (out of ignorance) that worm castings and compost are dangerous to use because of bacteria!

One of the biggest problems with using organic fertilizers, such as worm casting tea and compost tea, is that they are more likely to clog the spray nozzles in your aeroponic system. This can be reduced by using an in-line filter and/or prefilter with your system. You will still need to check the system often for clogged nozzles.

While worm castings do have many beneficial qualities, they are not a complete fertilizer. Mainly, they provide Nitrogen in a form readily available to your plants (that will not burn your plants). Other items will have to be added to your tea recipe to give it acceptable levels of Phosphorus, Potassium, and all of the necessary micro-nutrients. In addition, your formula will have to change when you switch the plants from veg to flowering.

A good place to start would be to try to duplicate the recipes found in two organic products called Super Tea and Budswel. They are both made by the same company....Super Tea is the veg formula recipe and is made of 1 part sifted compost, 1 part high Nitrogen bat guano, 2 parts worm castings, and some soluble seaweed. It has an N-P-K of 5-5-1.

Budswel is a supplement added to the Super Tea during flowering to increase Phosphorus levels. It has an N-P-K rating of 0-7-0, which leads me to believe it is made entirely of high Phosphorus bat guano, or possibly a mix of bat and seabird guano. Using equal parts of Budswel and Super Tea make a nutritionally complete tea with adequate Phosphorus to promote flowering.

Knowing what nutritional value each ingredient "brings to the table" is important if you are tying to customize or make your own recipe. Seaweed adds a relatively complete mix of necessary micro-nutrients. As an extra benefit, it also provides some plant growth hormones. Some tea recipes are brewed for a day or two (to grow populations of beneficial micro-organisms)....in these recipes seaweed provides a source of carbohydrate upon which micro-organisms feed and multiply.

Properly made compost has a well balanced N-P-K ratio, making it a good starting point for any tea. In addition, it is loaded with the very beneficial micro-organisms you want to promote. Adding it to your tea recipe inoculates the tea with these beneficials. Plus, the micro-organisms that created the compost have loaded it with humic acids and amino acids (which is a big reason why they are beneficial).

Bat guano is loaded with minerals and is in a form immediately available to your plants, but the main reason it is used is to increase Nitrogen (with high N guano) or Phosphorus (with high P guano), making any recipe very customizable. Well composted horse or cow manure can be used in place of guano to bump up Nitrogen levels.

It is a little more difficult finding organic additives to bump up Phosphorus levels. Clean wood ash has a lot of P, but it will also change the pH of the mix quite a bit (probably too much). Bone meal has a lot of P, but in using it you risk mad cow disease (your call). Perfectly good results can be had using just compost and seaweed, but most experienced gardeners like to shoot for bigger yields by adding extra Phosphorus during flowering in some way.

So you see, mixing your own tea is both an art and a science. If you decide to try a longer brewing method (one or two days), make sure to place an air bubbler in the bucket of water (with the nutrient). Beneficials need an aerobic environment to multiply, and an anaerobic environment will only promote pathogens.

Your next big challenge will be adjusting the strength of the nutrient tea once it is made. Using a TDS meter (or EC meter) is always a good idea, but with organic nutrients it can only be used as a general guide....organic nutrients read differently than standard chemical hydroponic nutrients. In addition to a TDS meter, use a visual test....most recipes need to be diluted with plain water until a glass full looks like weak tea (the kind you drink).

Lastly, you may read all of the above advice and decide it is too much work, too complicated, or beyond your current ability. If this is the case and you still want to go organic, check out this post, written to another visitor who had a question about using organic fertilizers in his aeroponic system. Hope this helps, and Happy Growing!