What Is Foliar Feeding? When And How To Foliar Feed

You may think of fertilizer as a product to be solely used in the soil, but you may be surprised to know that spraying nutrients onto plants’ leaves is another excellent way to provide your plants with nourishment. 

This method of fertilizing is called foliar feeding. In this article, we discuss the use of foliar fertilizing (liquid fertilizer) and share advice to help you make the most of this innovative way of feeding your plants.

Foliar feeding plants with liquid food

When To Use Foliar Feeding?

For best results, you should always use a product specifically intended to be applied to the plants’ leaves. 

Be sure to diagnose your plant’s problems carefully and accurately before applying a foliar fertilizers. Taking a generalized approach wastes materials and can be quite costly. 

Use Foliar Feeding When Your Plants Need A Nutrition Boost

Different types of nutrients are used to address specific plant conditions and needs. 

For example, the group of veggies known as Cole crops (e.g. greens, cabbage, broccoli) often suffer from magnesium deficiencies as evidenced by yellowing of the leaves

This can be addressed through the application of Epsom salts. This simple product can be applied as a spray and/or a soil additive.

Apply Micronutrients Routinely To Help With Nutrient Deficiencies

When your garden plants show indications of needing micronutrients such as:

  • Molybdenum
  • Manganese
  • Copper
  • Boron
  • Zinc
  • Iron

… applications of foliar food is a good way to provide them. 

A couple of applications of these important micronutrients applied twice per growing season results in strong, healthy plants. Just be sure the product you use is formulated especially for a foliar application so your plants will be able to absorb the nutrients. 

Additionally, test your soil pH level before making foliage spray applications of micronutrients. If the pH level is higher than 7.5, many types of plants will have trouble absorbing them efficiently through the leaves.

Use Foliar Feeding of Macronutrients When Your Plants Are Ailing

When routinely applying macronutrients, such as sulfur, magnesium and calcium, soil application is generally better than applying by a foliar method. 

Although plants in need can absorb some magnesium with Epsom salts spray applications, you should not count on foliar methods to provide all of your plants’ needs for this mineral.

The same holds true for calcium. You should routinely apply calcium to the soil, but if plants such as tomatoes or watermelons suffer from the condition known as blossom end rot, a foliar application of calcium can be very helpful in stopping it in its tracks.

Practice Foliar Feeds During the Coolest Times of Day

In terms of the best time of day for applying foliar sprays, very early morning, late afternoon or early evening is best. Applying a foliar fertilizer at these times will give your plants plenty of time to soak up the nutrients without having the moisture evaporate in the sunlight.

You should always follow the instructions on the packaging of any foliar feeding product you use. Failure to do so can cause a phytotoxic reaction or burning of the leaf tissue. 

This reaction can also be spurred by very high temperatures. Don’t apply a spray when the temperature is higher than 85° degrees Fahrenheit.

How Do You Apply Foliar Fertilizers?

To apply a foliage spray, you can use a hand-held spray bottle, a backpack sprayer or a spray attachment to your garden hose. The size of your garden will dictate the type of implement you choose.

Follow these guidelines for application:

  • Spray the entire plant – both topsides and undersides of the leaves.
  • Spray on overcast days because direct sunshine can rapidly dry out the product leaving a film of harmful salts on the leaves.
  • Avoid spraying immediately before a rain because this will dilute and waste your product.
  • Water before applying nutrient sprays rather than after.
  • For fruits and garden veggies, avoid applying nutrient sprays during the final month before harvest.

Remember that foliar applications should not be depended upon to provide all of your plants’ nutrient needs. 

The reason for this is that only about 15% to 20% of the nutrients you apply will be absorbed by the leaves because the top sides of the leaves are typically fairly well sealed by a waxy substance that is intended to protect them from the elements. 

The stoma, which absorb nutrients applied to the leaves are found on the undersides of the leaves. For this reason, when you apply a foliar spray, you should be certain to apply it carefully to the undersides of the leaves as well as the topsides.

What Plants Do Best With Foliar Feeding?

Young plants, plants with very tender leaves, and greenhouse plants will reap the most benefit from foliar spraying because their leaves are tender and better able to absorb the nutrients. 

More mature plants and/or those that tend to develop a thick protective layer over the top side of the leaves are less able to take advantage of nutrition applied to the leaves.
[source]

JOIN Our FREE Plant Care Newsletter 

By entering your email address you agree to receive a daily email newsletter from Plant Care Today. We'll respect your privacy and unsubscribe at any time.