Foliar Fertilization vs. Root Fertilization for Cannabis

Everyone knows the basic needs of every plant – sun and water. The sunlight interacts with the chlorophyll in the leaves to facilitate photosynthesis. The water is absorbed through the roots (and leaves) and acts as a transport system within the plant, also providing rigidity.

In addition to sunlight and water, plants need nutrients. As a matter of fact, nutrients are just as important as sunlight and water. It’s easy to forget about nutrients because traditionally, plants just pull them from the air and soil. And just as our knowledge of botany has grown, so have our advancements in nutrient delivery.

Getting to the Roots of Nutrient Delivery

Before we jump into innovations in nutrient delivery systems, let’s take a look at why nutrients are so important to the development of healthy, high-yielding cannabis plants.

NPK and Other Essential Nutrients

There are 16 nutrients that cannabis plants require to grow, develop, and bud. Six of these nutrients make up over 95% of the plant’s weight and mass. Those nutrients / elements are:

  • Carbon – Absorbed from the air.
  • Oxygen – Absorbed from the air.
  • Hydrogen – Absorbed from water.
  • Nitrogen – Absorbed from the soil or nutrient solution.
  • Phosphorus – Absorbed from the soil or nutrient solution.
  • Potassium – Absorbed from the soil or nutrient solution.

The vegetative structures of all plants, including cannabis, are made of carbon. Plants use oxygen for respiration, like all biological life. Oxygen is necessary for plant cells to make energy available for a wide range of activities. You can read more about the benefits of balanced plant nutrients here.

General Hydroponics HGC718045
Liquid nutrients such as FloraGro provide critical minerals such as nitrogen, phosphorous, potassium to your cannabis crop.

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Each nutrient is critical for cannabis and hemp plants to grow strong and healthy. Delivering these elements to your cannabis plants is very important to ensure increased flowering and greater trichome yields. And the two primary points of absorption are via the roots or the leaves.

Introducing Hydroponics: Innovating Root Fertilization

By far, the most common form of root fertilization has been through good, old-fashioned dirt. This type of solid-medium fertilization is often accompanied by pests, varied fertility, and the challenges associated with remote horticulture in locations with very little soil (or none at all.)

As conventional mitigation of these issues became increasingly difficult, new solutions for mass-agriculture began to emerge. In the 1860’s, there was an experiment by two German botanists that resulted in the first, standardized nutrient solution (liquid medium) for plants.

William Frederick Gericke
William Frederick Gericke is known as one of the pioneers of modern hydroponic cultivation. He is attributed with coining the term, “Hydroponics.”

The nutrient solution would remain “just an experiment” until later in the 1930s, when William Gericke applied his method of growing crops in a soilless medium. Enter the official introduction to hydroponics. The results were undeniable, although mainstream horticulture was not yet ready for the shift.

Fast-forward to today’s modern cannabis cultivation grow rooms and greenhouses. Not only are hydroponics widely accepted, this method of root fertilization has been optimized to greatly improve cannabis plant yields.

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Turning Over a New Leaf – Nutrient Supplementation

The process by which critical plant nutrients are supplemented by means of spraying their leaves has been around for over 100 years. When performed correctly and under the proper conditions, foliar fertilization can be a powerful addition to a cannabis farmer’s tool-kit.

What is Foliar Fertilization?

The term “foliar” is defined simply as, “relating to leaves.” And so it comes as no surprise that Dr. Derrick Oosterhuis of the University of Arkansas defines foliar fertilization as,

The application of foliar sprays of one or more mineral nutrients to plants to supplement traditional soil applications of fertilizers.

Dr. Derrick Oosterhuis, Presentation at 2007 Indiana CCA Conference

Foliar fertilization is becoming increasingly popular, and for good reason. It works. Cannabis plants growing in soils that have reduced availability of nutrients such as Nitrogen or Potassium are perfect candidates for foliar sprays.

Although foliar absorption can be highly efficient, cannabis plants require large amounts of critical nutrients. Plant leaves are not designed to absorb minerals in the quantities required to support its development.

It’s important to note that foliar sprays should not be used to replace soil or hydroponic delivery systems, rather in conjunction with them. Foliar sprays are perfect for supplementing and quickly correcting nutrient imbalances within a cannabis crop. This can save malnourished plants and help maximize trichome yields.

Note: Foliar spraying is also widely used to apply natural pesticides (such as Neem Oil) to the leaves and stems of cannabis plants to increase their natural immunity to insects and fungus.

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Foliar Sprayers and Wands

Most cannabis cultivators utilize foliar spraying without even realizing it. Whether you are supplementing nutrients or battling mold and insects – the solution to keeping your prized crop healthy will involve applying an NPK or Neem oil solution to the leaves and stems of your plants.

Before we show you a few options for foliar sprayers, let’s review a few best practices. You can reduce waste and improve foliar absorption by following a few rules of thumb:

  1. This may be obvious, however don’t apply a nutrient or pesticide prior watering your cannabis plants.
  2. Always be sure to thoroughly spray both the top and undersides of the leaves.
  3. Double check your nutrient solution concentration. If it’s too strong, you can damage the leaves of your plants.
  4. In most applications, avoid foliar sprays when your cannabis plants are flowering.
  5. It’s generally a good idea to use the finest mist available on your hand or backpack sprayer to achieve maximum surface area coverage.
  6. Always verify the instructions included with your pesticide or nutrient solution and don’t be afraid to ask questions!

Finally, cannabis and hemp cultivators need some basic equipment to apply their nutrient solution. At Omega, we have several options to help meet the needs of your greenhouse and grow room.

For smaller grow rooms and premium cannabis crops, we have 2-liter hand sprayers. Always be sure to wash and rinse sprayers if you must use it for multiple types of solutions or pesticides. Ideally, you’ll want to have dedicated sprayers for mineral supplementation vs. pesticides.

Rainmaker Lithium Ion Backpack Sprayer
For larger crops of cannabis and hemp, rechargeable backpack foliar sprayers save farmers and cultivators time by eliminating manual pumping and reducing the number of trips to refill.

If you have a large grow room or greenhouse, backpack sprayers allow you to scale your foliar spraying. This will save you time by both reducing manual pumping, as well as saving you several trips to your supply room to refill.

Sometimes you will need to apply a solution to all your cannabis plants. And other times you may only need to spot-treat plants that require additional nutrients or Neem applications. We offer a variety of foliar sprayers so you can find the best applicator for your cultivation business.

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Is Root or Foliar Fertilization Better?

If you’re debating which method of fertilization is best for your cannabis and hemp crop, the answer is simple: both. Ensuring your hydroponic solution and soil have the proper balance of minerals is critical because this is how plants get most of their nutrients.

If the leaves of your cannabis plants start to become discolored or wilted, test your soil or solution to determine which nutrient they need supplemented, and then use a foliar sprayer to quickly course-correct. By balancing both, you ensure strong vegetative growth and larger blooms.

Need more help?

We hope you found this article helpful and informative. Keeping your plants safe from insects and providing them the essential nutrients they need is important and we’re here to help.

If you have questions about our selection of nutrients and which solutions are the best fit for your needs, feel free to reach out to our team. We’re happy to help and provide additional resources and answer any other questions you may have.

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