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Many growers won’t reach for the spray bottle until they see a deficiency or pest issue and desire a “quick fix.” However, as Everest Fernandez explains, foliar feeding—spraying nutrients directly onto plants’ leaves—should arguably be part of your weekly garden schedule.
How Does Foliar Feeding Work?
Nutrient Uptake through Leaves
Imagine the leaf as a bustling hub. Light hits the leaf, allowing the tiny engines inside, known as chloroplasts, to convert water and carbon dioxide into glucose through photosynthesis. This glucose powers the plant and contributes to the compounds we aim to produce. Did you know a whopping 95% of a crop’s weight comes from photosynthesis?
So, how does foliar feeding help? In 1956, Dr H. B. Tukey’s research unveiled an exciting discovery. Using radioactively tagged nutrients, he found that plants absorbed nutrients not only through roots but also through their leaves, and incredibly, they do so 8 to 10 times more efficiently via their leaves. This suggests that direct application to the leaves can provide nutrients where needed, boosting photosynthesis and the plant’s overall metabolic rate.
However, there’s a challenge: the leaf’s waxy cuticle. It acts as a barrier. But science has a solution: special wetting agents that can penetrate this barrier without harming it, allowing nutrients to enter the leaf efficiently. This direct delivery to the leaf’s active parts results in a quick, beneficial response.
Understanding the Leaf’s Inner Workings
Once inside the leaf, nutrients face barriers like the cell wall and membrane. Most supplements can easily pass the porous cell wall. The cell membrane, however, is pickier. Some nutrients can move through effortlessly, while others need special channels or processes to get inside.
The good news is that plants have various methods of allowing these molecules inside, such as facilitated and active transport.
The Case for Foliar Feeding: Best Way to Apply Foliar Fertilizer
Foliar feeding’s benefits go beyond just nutrient uptake. Certain supplements, like those that enhance photosynthesis, work best when applied directly to leaves. Evidence suggests that foliar-applied nutrients can be more efficiently absorbed than root-based nutrients. For instance, a study by the University of Florida found that foliar application of certain nutrients led to substantially larger citrus fruits than ground applications.
Chelated nutrients are wrapped in molecules to aid absorption and are particularly beneficial when applied as foliar sprays. They’re absorbed and distributed more evenly throughout the plant. Urea, another substance, when foliar applied, provides an efficient nitrogen source for plants, bypassing the challenges it faces when applied to soil.
Get Seaweed Extract in the Mix!
Also, seaweed extracts, especially from types such as Ascophyllum nodosum, are increasingly recognized for their efficacy as foliar spray biostimulants. These solutions contain valuable elements, like cytokinins, auxins, betaines, and essential minerals, all enhancing plant health, growth, and robustness. Plants, when faced with adversities like drought, salt stress, or threats from pests and diseases, can find relief with the application of these seaweed solutions. These sprays support plants by boosting their antioxidant defenses, regulating water balance, and fostering the production of proteins and enzymes crucial under stress. Furthermore, these seaweed-infused sprays can lead to better nutrient absorption, invigorated root systems, and augmented crop yields.
Key Takeaways
Foliar feeding offers a range of benefits, from increased yields, disease resistance, and improved drought tolerance to faster nutrient deficiency remedies and enhanced crop quality. While the method’s efficiency varies, it can be up to 20 times more effective than root application. Still, while it’s a valuable tool, foliar feeding shouldn’t replace a comprehensive root-fertility program. Instead, it should be seen as a fantastic supplement to optimize plant health and yield.
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