Foliar Spray: What Is It and Do I Need It?

Image shows a women spraying Foliar Spray onto a plant.

Growing and maintaining healthy plants isn't always an easy task.

Sometimes, even when everything seems to be going right, they still might not be able to obtain enough nutrients through soil alone for whatever reason.

One way to address this issue is foliar spray, a somewhat controversial method whose popularity, despite the concerns of skeptics, has grown tremendously in recent years.

While foliar spraying isn't by any means a replacement for healthy soil, it's a fast and easy way to boost the nutritional needs of your plants. 

In this article, we'll discuss this unique method why it might just be right for you. 


Woman spraying plant


What is Foliar Feeding?

Foliar feeding is the technique of spraying the leaves of a plant with a dilute mixture of water and fertilizer. As opposed to traditional fertilizer, which is absorbed by the roots and stem, the spray is taken directly by the foliage.

The liquid foliar solution enters by way of stomata — tiny openings on the undersides of plant leaves. These pores allow gases such as carbon dioxide, oxygen, and hydrogen, which are involved in the process of photosynthesis, to enter the plant during the day. At night, the stomata close, since light is unavailable and photosynthesis can no longer take place. (Note: it's essential to spray only when the stomata are open). 


Sun beaming through the trees creating a glare


Stomata are also able to absorb nutrients and quickly transport them throughout the entire plant; hence, the utility of direct foliar feeding. 

Many studies have demonstrated the efficacy of foliar spraying. For example, a University of Michigan research trial showed an increase in yield from 12% to 25% when compared to conventional fertilization. The study also found that when liquid fertilizer is directly sprayed onto to foliage, more than 90% is used by the plant, but when a similar amount is applied through soil, only 10% is utilized. 


Why is it controversial?

Skeptics of foliar spraying often point to the fact that by nature, leaf surfaces aren't built to take in nutrients like the roots and stem are. After all, the primary function of stomata is to regulate the flow of gases that aid in phototosynthesis — not to absorb nutrients from liquid fertilizer. 

Many people would claim that plants already receive sufficient nutrient uptake from suitable soil that is kept healthy and properly taken care of, so there's no need for additional feeding, especially since direct spray provides a more concentrated fertilizer dose, which can contribute to leaf burn over time.

Additionally, the science on this issue is somewhat mixed. While much research has shown that foliar feeding significantly increases plant yield and quality, there exist other studies that show no effect or even indicate the contrary. 


Various houseplants


Benefits of Foliar Feeding

When feeding exclusively through soil, there are so many things that can go wrong, especially for outdoor plants. In other words, there is a wide range of environmental conditions out of your control that may impact soil quality and inhibit nutrient absorption. For example, the negative influences of pests, extreme temperatures, and dryness can all hinder the plant's ability to take in essential nutrients.

Foliar fertilizers are great supplements for plants that may be unable to receive enough nutrients from the soil alone. This is particularly helpful for houseplants like Bonsai trees, which grow in small pots without access to very much soil in the first place and don't receive organic nutrients from fertilizers in nature like decomposed leaves and manure.

Direct foliar spraying allows for more precision and efficiency in feeding. Instead of applying large quantities of fertilizer into the ground, much of which will not even be used up, you can use foliar spray to target and treat specific nutrient-deficient plants. 

Foliar feeding also takes place quickly. Direct absorption from the leaves means that nutrients bypass the root vascular system and are essentially fast-tracked to parts of the plant that need them, so you'll see results almost immediately! 


Many leaves with rain droplets on them


Types of Foliar Feeding

There are generally two types of foliar feed: water-soluble powder, which requires you to mix with water to create the spray, or liquid solution, which requires no additional preparation.

If you're making a mixture, there are many pre-made powders available on the market. However, many people actually prefer to create their own homemade recipes using natural ingredients such as seaweed, herbal tea, and fish emulsion. You can find examples of various easy homemade recipes online. 

Also remember that you'll also need an effective sprayer. For small potted plants, a typical hand-held bottle will do. For outdoor plants and crops, you'll probably need a larger backpack sprayer or a spray attachment to your garden hose. 

On the other hand, pre-made liquid solution, such as Shin Nong's own PRO ORGANIC fertilizer, typically comes in a convenient, ready-to-use spray bottle. Just follow the instructions on the label and spray away, and you'll see results in no time! 

Regardless of which type you decide on, rest assured that the right foliar spray can serve as a quick and efficient way to provide necessary nutrients to plants around or outside the house.


Spraying plant outside


Our Perspective

At the end of the day, foliar feed is of course no replacement for healthy soil, but it can serve as a fantastic treatment for nutritional deficiencies and help ensure healthy plant growth if applied correctly. (Check out our blog on how to correctly apply the spray.)

Although there does exist some skepticism within the scientific and plant-growing community as to whether foliar fertilizers are entirely necessary, most would agree that they can indeed be used as a quick and efficient supplement to boost nutrient uptake and leave your plants looking lush, green, and healthy. 


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