Spraying leaves with nutrients? Isn't that what soil, fertilizer, and hydroponic nutrient solutions are for?
Foliar Sprays offer a method for rapid nutrient delivery. It can be used as part of a nutrient regiment, but it is particularly beneficial in treating specific nutrient deficiencies and for reviving stressed or diseased plants.
SCENARIOS
When a plant is suffering from certain nutrient deficiencies.
When your environment has high heat. When temps are high, the plant transpires more moisture through its stomata to dissipate heat.
In systems without soil, such as hydroponics, nutrient interactions can occur within the root zone that makes it difficult for plants to absorb certain minerals due to binding and antagonism between the nutrients. Iron deficiency occurs in many of these crops when they are stressed by low temperatures. Therefore, hydroponics have a special need for foliar feeding.
WHAT TO USE
Mostly water!
Nutrient Solutions - Most nutrients can be absorbed through the plant's stomata via foliar spray. A good rule of thumb with foliar sprays is to always use diluted formulas. This will prevent burns! You'll want to go with quarter of what the nutrient bottle suggests. This is the MAX you should add. More is never better in terms of nutrients.
Wetting Agents - Wetting agents reduce the surface tension of the solution you are spraying. This allows the solution to cover the leaf surface, and makes it much easier for the leaves to absorb the solution through its stomata (pores). A great natural wetting agent is Yucca Extract.
Gardin carries solutions specifically designed for foliar spray mixtures. Our favorite option is Rain by Roots Organics. This liquid formula contains fully dissolved Yucca extract which cant be added to the nutrient solution you wish to spray on the leaves.
HOW TO USE IT
Apply the solution via spray bottle until droplets cover the leaves. The best time to apply is just before it becomes dark. In other words, in the early morning before the sun is strong or before you turn lighting off.
Never apply during full light hours! This is because these droplets act as mini magnifying glasses, and the light rays will burn the surface of your foliage.
Resources:
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http://blog.nutri-tech.com.au/top-10-most-frequently-asked-foliar-fertilising-questions/
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http://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/what-is-foliar-spray.htm
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4hydroponics.com video - https://www.youtube.com/watch?v=5281F_UgDtY