Foliar feeding is an excellent way to get your plants the nutrients they need fast and efficiently. Compared to traditional nutrients that are taken up through the roots of your plants, foliar feeding is completely focused on the foliage.
When using normal liquid or powder nutrients/fertilizers, they are typically blended in with water and applied to the root zone. This method of feeding is the most common, as your roots are typically where the most nutrients are absorbed.
But feeding through the root zone can take time. Some nutrients have delayed absorption rates which can take several applications before taking effect. Sometimes plants need immediate supply of nutrients and just can’t wait.
Foliar feeding is the solution to this problem!
How does foliar feeding work?
Unlike traditional nutrient applications that would involve simply pouring a diluted mixture into the root zone or using automated irrigation to deliver the solution from a reservoir, foliar feeding can only be applied via spray.
Foliar feeding allows for nutrients to pass into the vascular system of your plants directly through leaf and stem absorption. This process makes nutrients more readily available to your plants so they can be utilized right away.
This is particularly useful for growers who may have a nutrient deficiency such as calcium or magnesium deficiency, especially with multiple plants dealing with the same issue. While a normal nutrient solution may take several days to impact your plants, a foliar spray can take effect in just a few hours or a couple days of repeated use.
However foliar spray can't just be sprayed whenever you want. Using foliar spray at the wrong time or in the wrong environment can have negative consequences.
When NOT to use foliar spray
The most important factor that you never want to forget, is when foliar feeding is appropriate. The only thing to remember in this regard, is that you never want to apply a foliar spray with the lights on.
Just to reiterate; NEVER spray your plants with the lights on. ALWAYS spray with the lights off. Why?
When you apply a foliar spray to your plants, you're leaving little beads of water all over it. With high powered grow lights or the sun beating down outdoors, those little beads act like tiny magnifying glasses, focusing the light on your leaves, causing burning.
Your plants cannot absorb the liquid through its leaves and stems quickly enough, so this will always be an issue.
While some foliar products have the ability to be sprayed with the lights on, it is always better to be safe than sorry. Only a small handful of foliar products can be sprayed with the lights on, and it won't ever hurt to spray with the lights off even if the product can be sprayed with them on, just to develop the habit.
Foliar feeding can also be damaging to your plants later in flower, as the spray will start impacting more than just leaves and stems, including flower sites.
How foliar feeding is done
Foliar feeding is prepared the same way as traditional nutrient applications. It is simply applied in a different method.
First, ensure that the product you are using can be used as a foliar spray. Some products give you the option of using them as a normal root drench or a spray. Avoid using products as foliar sprays if they don't explicitly claim the ability to be used in that manner.
Dilute the nutrient or supplement according to its dilution rates on the label, and then simply fill a sprayer bottle and begin spraying. Plenty of products designed for foliar spraying will be ready to use straight out of the bottle, no dilution needed.
During the vegetative phase, you can spray your plants and cover them completely, leaves and stems. Again, avoid foliar feeding late in flower if you have consumable flowers to harvest.
Should I use foliar spray?
Overall, it depends on your current nutrient regiment, how far along your plants are, your grow environment and other factors. While you could go through most of your growth cycle only feeding via foliar applications, most people don't.
Your plants require plenty of different nutrients to thrive, and some of them (and some of the most important) are absorbed much more efficiently through the roots.
Knowing the best applications for foliar feeding and whether it will be beneficial to your grow will aid in making your decision.