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Cannabis plant with vibrant leaves absorbing nutrients and beneficial microbes, representing the power of foliar feeding.

Unlocking Plant The Complete Guide to Foliar Feeding and Microbial Applications

Ever wondered how to give your plants a direct energy boost? Enter foliar feeding—a cutting-edge technique that delivers nutrients and beneficial microbes right where your plants need them most: their leaves. This isn’t just a surface-level fix; we’re talking about nutrients that get rapidly absorbed through the leaf stomata and immediately put to work at the cellular level. Imagine bypassing the usual nutrient of root absorption, offering your plants a fast-lane to growth and vitality.

But it’s not just a speed game. The environment, the makeup of your spray, and even the size of the particles all play roles in how effective your foliar application will be. We’ll dive into the nitty-gritty, covering everything from stomata function and leaf transpiration to the science behind bacterial and nutrient foliar sprays. By the end of this article, you’ll be equipped with personal techniques and know-how to optimize your plant’s health and yield like never before.

The Integrated Science of Nutrient Foliar Application

In the realm of plant cultivation, foliar application serves as a direct channel for nutrient and biological uptake, bypassing the root system for immediate cellular absorption. When root health is compromised or rapid nutrient delivery is needed, foliar applications can bypass the root system and directly nourish the plant. This section elaborates on the key elements—amino acids, calcium, and phosphorus (often enhanced with fulvic acid)—that serve as the backbone of foliar feeding. These elements not only facilitate rapid cellular development and enzymatic processes but also amplify metabolic and flavonoid pathways. The synergistic interaction among these elements enhances plant health, stimulates root exudates, and consequently elevates microbial activity and rhizophagy cycles in the soil.

Recipe for Nutrient Foliar Application (One Gallon)

  • Soy Aminos (agmino): 1 tsp
  • Micronized rock phosphate: 10 grams
  • Micronized Calcium Sulfate: 6 grams
  • Fulvic acid: 10 ml

Crucial Elements for Foliar Feeding: Amino Acids

Amino acids, as our nitrogen source, provide several benefits. Amino acids are the building blocks of proteins, the foundation of every cell. The plant spends no energy to utilize them, and they provide immediate energy for the plant. Enzymes are long chains of amino acids. These enzymes catalyze many processes in the plant. Introducing amino acids gives the plants what they need to form the enzymes crucial to those processes. There are twenty amino acids in nature, each serving a specific function. Maximize the profile of amino acids in your garden and your foliar sprays. I like to use soy amino acids; however, you can also use fish amino acids. It is also an option to use Aloe Vera, which contains 19 of the 20 amino acids. However, finding an aloe vera product that won’t clog your sprayer will be tricky. There are many products on the market full of amino acids.

Calcium: An Essential for Plant Health

For my Calcium source, I like to use micronized calcium sulfate. In its micronized form, it can penetrate directly into the cell walls. This product provides maximum solubility that can be used safely through irrigation lines and will not clog sprayers and atomizers. Calcium is vital for cell walls, cell division, and enzyme activity. Plants may display signs of calcium deficiency even when plenty is in the soil. Several factors can cause this, but foliar applications bypass these issues.

The Significance of Phosphorus in Plant Growth

Phosphorus is a critical component in ATP production, the primary energy source of all plant cells. Plants also use phosphorus to create DNA, RNA, lipids, and cell membranes. Phosphorus also influences protein functions that signal transduction pathways and stimulate metabolic pathways; it is also a component in forming coenzymes, which assist enzymes in their activities. When introducing phosphorus as a foliar application, I use micronized rock phosphate, which provides the same benefits as the previously mentioned micronized calcium.

Microbes: The Hidden Beneficiaries of Foliar Application

In addition to foliar applications of nutrients, microbe applications to leaf surfaces are also very beneficial. Disease prevention, nutrient uptake, plant growth promotion, induced systemic resistance, bioremediation of pollutants, strain tolerance, improved photosynthesis, and extended shelf life can all be connected to biology on the leaf surface.

Crafting an Microbial Foliar Spray

Be wary of products that contain lactobacillus within the product that claim also to have other consortiums. Lactobacillus is an “opportunistic” microbe. It is very voracious and will out-compete other microbes quickly, likely resulting in a monoculture of lactobacillus. Although lactobacillus is a great microbe for foliar applications, I recommend adding it separately when mixing your microbial foliar spray. Adding it last gives us the benefit of lactobacillus without out-competing the other microbes in your foliar spray. Remember not to do microbe-based foliar sprays when you have buds on your cannabis plants. Only do this during the vegetative growth stage. Here is a simple microbe-based foliar spray I like to use:

Recipe for Microbial Foliar Spray (One Gallon)

  • Photosynthesis Plus: 10 ml
  • Lactic Acid Bacteria Serum: 5 ml
  • Slf100: 5 ml
  • Yucca Extract: 5 ml

Refer to my past articles for information on how to make lactic acid bacteria serum. I like to alternate my foliar sprays between nutrient and microbial. It’s safe to use foliar sprays daily but unnecessary unless you are fighting a deficiency. One every week is fine. This recipe has a powerful odor.

Exploring the Role of Endophytic Bacteria in Foliar Applications

There are a few key concepts to understand when doing this. Let’s go over endophytic bacteria first. Endophytic bacteria are microorganisms that live within the plant cells symbiotically. They provide a service to the cell, and the cell provides a service to them. For example, endophytes will enter the cells of a plant and use compounds within the cell to create phytohormones for the plant directly where the cells need them. Endophytes can produce phytohormones like Indol acetic acid (auxin). This phytohormone will boost plant growth rates and is responsible for many crucial aspects of a plant’s growth. Many different endophytes can produce phytohormones. Endophytes also possess the ability to create disease and pathogen-suppressing compounds. They’re also able to take toxins from pollutants and bio-remediate them. Not only will these microorganisms produce phytohormones, but they also create enzymes that catalyze significant processes in the plant cells. Combined with foliar application of nutrients, this is a  tool.

Here is a list of common plant endophytes:

Common Plant Endophytes Suppresses Pathogens Enhances Plant Growth Fixes Nitrogen Enhances strain Resistance
Bacillus subtilis
Bacillus amyloliquefaciens
Pseudomonas fluorescens
Pseudomonas putida
Azospirillum brasilense
Burkholderia phytofirmans
Enterobacter cloacae
Methylobacterium spp.
Herbaspirillum seropedicae
Klebsiella pneumoniae
Serratia plymuthica

Recommendations for Microbial Foliar Spray

Many of these endophytes can be found in earthworm castings, you can make a compost tea to apply them to your plant’s foliage. However, this can be difficult when using a sprayer as they will clog your nozzle. If I’ve made a compost tea, I will water the foliage of my plant with it, providing it with goodness to the soil and foliage. There are more controlled ways to do this also. Many bottled inoculants on the market contain endophytic bacteria you can spray through a sprayer. One that I like to use is called photosynthesis plus. It is a consortium tailored to increase photosynthesis rates but also provides many other benefits. There are many products out there. Find one that works for you. If you decide to use this product, it’s essential to know it does contain sulfur and may not be compatible with other IPM products. Never mix sulfur and oil in a foliar spray. Separate oil and sulfur-based products by two weeks when spraying.

The Integrated Approach to Foliar Feeding

Integrating nutrient and biological foliar sprays into your garden provides a synergistic approach to plant health and vigor. Nutrient sprays provide plants with essential elements for growth, while biological sprays introduce microbes such as endophytes and bacteria. Together, they work symbiotically with plants to improve nutrient uptake, enhance disease resistance, and boost strain tolerance. Together, these treatments promote a vibrant garden ecosystem where plants thrive. By adopting these strategies, you can reduce the need for synthetic chemicals and maintain a more sustainable and eco-friendly cultivation practice. Integrating both these approaches encourages short-term plant health and the long-term vitality and resilience of the entire garden.

Foliar application of nutrient research

https://nph.onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2012.04307.x https://www.nature.com/articles/s41598-022-09247-0 https://bjbas.springeropen.com/articles/10.1186/s43088-022-00210-6

Foliar application of microbes research

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9560770/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7734409/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8151188/

About the Author: Luna Whitcomb

Luna Whitcomb is a trailblazer in the field of organic cannabis cultivation with over 14 years of experience in various cultivation methods. Specializing in living soils rich in symbiotic biology, Luna has developed and operated both large and small-scale facilities and hemp farms. She brings an integrated approach to cannabis cultivation, combining her knowledge in microscopy, biology, entomology, agronomy, and enzymology. Her expertise particularly shines in the area of foliar feeding applications, a subject she passionately explores to optimize plant health and yields. Luna’s rich career includes educating thousands of cultivators through diverse platforms and contributing valuable content to the cannabis community.

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