What teas should I use with my living soil?

The purpose and application of teas in conjunction with your plants is an area that we often get questions about. There is a lot of confusion with regards to what a ‘tea’ actually is, and what roles they play in your garden. I believe that some of this confusion stems from people who are transitioning from their hydroponic background over to soil, yet do not truly understand the principles behind a living soil approach. Some people understandably hold onto their past experiences and ideas that when growing in an hydroponic medium, certain nutrients need be applied at certain stages of growth and continue to think that the use of teas is a substitute for the feeding of the nutrients that a plant might need at a particular stage. This is true to a limited extent, however the correct term here is foliar feeding. Teas are generally used for a different purpose than foliar feeding, yet the two terms can be and often are interchanged.

Foliar feeding is a method of applying liquid nutrients through fine sprays to the tops and bottoms of the leaves of your plants, as opposed to feeding these nutrients directly to the roots as a drench. This is a very efficient way to get indispensable nutrients directly into the cellular structure of your plant as these elements are easily absorbed through the epidermal layer or surface of the leaf structure.

If you look at a leaf surface under a microscope, you will see miniscule apertures or openings on both the top and bottom of the leaf which are called stomata. These openings allow for water vapor, oxygen and carbon dioxide to move into and out of the leaf structure. The plants leaves are, in effect, the food manufacturing organs of the plant. It is here in the leaves that the process of photosynthesis takes place and the stomata are the gateways through which the plant can obtain the critical nutritional elements needed to complete the photosynthetic process.

A light misting of a nutrient bath onto the upper and lower surfaces of the leaf in the cool of the morning- before the stomata have closed off due to the increased temperatures of the day, will direct these nutrients efficiently into these food manufacturing organs where they can achieve the greatest impact. The great benefit here becomes apparent when you consider that this very efficient method of ‘topping up’ the nutrient spectrum of the plants' requirements then results in greater and more efficient sugar production [photosynthesis]. This, in turn, results in a greater amount of root exudates being pushed down through the roots into the rhizosphere, where it feeds and stimulates the soil biology even further.

That said, foliar feeding is not a replacement for feeding the roots- some macronutrients such as nitrogen, phosphorus and potassium are needed in larger quantities and for this reason are best taken into the plant through the root system. However, there are many micro nutrients that can readily be absorbed through the ‘skin’ of the leaf, thus getting directly into the leaf structure.

Teas, on the other hand, especially compost teas, are generally applied in order to build the life in the soil as well as the phyllosphere of your plant, which is the surface area of your plant that can be found above ground. This leaf and stem area represents the largest terrestrial habitat for microorganisms on earth and these microbiota in turn have tremendous significance for your plant health and vigor. It is on and through the leaf surfaces that many pathogenic organisms are able to gain a foothold and colonize these surfaces, often resulting in a compromise to plant health. However, this can only happen if the pathogens are able to out compete the existing beneficial microbiota that are found on these surfaces.

When a high quality compost is combined into a brewer with water and a catalyst food source, and oxygen is ‘bubbled’ through this liquid, generally for 24 hours, the microbial populations from the compost are washed into the water. In this highly oxygenated environment, they explode in numbers. If you consider that a single gram of compost might contain as much as 15,000 different species of micro organisms, then you can see the value of adding dissolved oxygen and a food source to satisfy the growth of the compost biology. The result is a microbially rich and dense soup that is then taken and sprayed onto the plants and soil, in order to introduce these microbe populations to these surfaces. When applied in the early stages of plant growth, these communities of beneficial microbes can be firmly established and are then able to suppress and outcompete the growth of many pathogenic communities.

If you have built a strong nutritional ‘battery’ for your plant through the careful amending and balancing of the minerals and nutrients in your soil, then you can begin to rely on teas to help strengthen the beneficial bacterial and fungal colonies that are found in both the rhizosphere and phyllosphere.