What Is Foliar Feeding? Does It Benefit Plants?

What Is Foliar Feeding? Is It Worth It As A Canadian Gardener?

Does Foliar Feeding Plants Really Work?
Does Foliar Feeding Plants Really Work?

As a soil scientist my main priority is ensuring plant health is at its peak. However when we run into issues such as a poor root system or undesirable pH action outside of the soil is required. Foliar feeding is the perfect solution for meeting the needs of a plant in need of some TLC. In this gardening in Canada blog post we will be looking at the science behind how effective foliar feeding is and whether or not you should try it.

What Is Foliar Feeding?

Foliar feeding of plants is simply delivering nutrients via the stomata on a plant leaf. This is in stark contrast to the typical nutrient delivery system which is the soil. Foliar feeding arguably is a hot topic with lots of controversy and debate.

Initial idea of foliar feeding was brought forth in a study done in the 1950s. This study concluded that plants are able to take nutrients through the leaves. This is done via specialized organs on the bottom side of the plant which are called stomata. The stomata are regulated by guard cells.

How Is Foliar Feeding Taken Into The Plant?

Stomata are known for their role in photosynthesis and respiration. It wasn’t until the study that the idea of providing nutrients through the stomata was possible. Since the study in the 1950s there have been other studies done looking at foliar feeding and its success. As well as an equal number of studies critiquing the process.

Needless to say the results are all over the map. However there is one commonality throughout all the studies. This commonality is the fact that there is an undoubtable benefit to foliar feeding your plants in a high stress scenario. This is particularly true if the plant roots are the source of the stress.

Foliar feeding can help you get through a bout of root rot, poor pH, and overall changes in soil environment. What foliar feeding will not do is provide essential nutrients in a high enough quantity for a plant with a proper functioning root system. 

Purpose Of Foliar Feeding 

When looking for a proper definition for the purpose of foliar feeding it is important to take into context the condition of the plant. This is why I would characterize foliar feeding as an emergency nutrient delivery system. This means the purpose of all you’re feeding is specific to plants under stress, in particular route stress.

The purpose of foliar feeding comes down to whether or not the plant is healthy. If a plant has a healthy root system it is able to uptake all the nutrients it needs to survive. This means foliar feeding can be detrimental and potentially harmful to a healthy plant.

The only other time I would say it is advantageous to be foliar feeding is in poor soil nutrient conditions. For example if you have a sandy soil that is not able to hold onto nutrients and you’re in the process of improving the soil conditions you may want to consider foliar feeding your plants. This means a healthy plant in a poor soil condition is able to benefit from a foliar feeding schedule.

Macronutrients & Foliar Feeding

Foliar feeding for the purpose of macronutrients is nearly useless. It’s as simple as that. Plants that have a healthy root system are efficient in the uptake of macro nutrients. While there are some exceptions to this such as calcium and magnesium. For the most part plants looking for nutrients such as nitrogen, phosphorus and potassium are all bio available for plant needs even when the plant is stressed.

This is due to the wide pH in which the plant nutrients are absorbed into the plant. If you didn’t know nutrient bioavailability to plants is greatly affected by the soil pH. The macronutrients of a plant have a wide range of pH that can allow for absorption.nutrient deficiencies typically are caused by poor soil conditions rather than lack of nutrients. For more on this check out my YouTube video on soil pH and how to test for it.

Micronutrients And Foliar Feeding

If you’re feeding micro nutrients this is exactly what foliar feeding was designed for. Because micro nutrients have a very sensitive window in pH values and absorption. When the pH of the soil is less than ideal these micro nutrients are not bioavailable for plant uptake.

Due to this phenomenon foliar feeding has found its place in the industry. Micronutrients are needed in small doses and therefore utilizing those tiny stomata pores is an ideal setup. Micronutrients is also helpful in helping a plant survive a stressful situation.  

What Is Used In Foliar Feeding?

When we look at foliar feeding products we tend to see both major brands and homemade DIY solutions. The truth is that the DIY foliar feeding solutions do not always work. This is because foliar feeding was initially developed by fertilizer companies. This means all the research that has gone into the industry standard foliar feed products. Industry forms of the foliar feed contain surfactant that will help the product stick to the leaves.

What is the home DIY foliar feed sprays is different from the industry grade products. This is because the industry standard for your foliar feeds is the use of surfactants. Which helps the mixture to stick to the leaves. In a home made solution it is likely that the fertilizer will simply roll off the surface. This means there will not be in time for it to be absorbed through the stomata.

In theory if you are making foliar feeds at home you will want to add a cling factor to the mix. The readily available cling factor would be the addition of dish soap. The soaps presence will help the fertilizer cling to leave after being applied. This will allow for ample time of absorption and therefore fertilization.

Easy DIY Foliar Spray

Simply take a fertilizer with a broad spectrum of nutrients and add it to the recommended level of water. From there pour the solution into a 500 ml spray bottle, leaving a small amount of room. To this spray bottle you will want to add approximately 5 drops of dish soap.

Give this solution a shake and you are officially have a DIY foliar spray that works. For tips on DIY pest recipes check out my pest blog post.

You are now prepared for foliar feeding success

It’s official you are now prepared to succeed in foliar feeding. Keep in mind the purpose of foliar feeding is to help plants that have a stressed root system or are in poor soil conditions. If you notice that your plant is in this condition try utilizing this method to help provide much need micronutrients.

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