Learning How To Foliar Feed Cannabis

Foliar feeding can provide cannabis plants with nutrients and protection directly through their leaves, allowing for faster absorption than traditional root feeding. Instead of applying fertilizer to the soil, growers use a foliar spray to deliver a liquid solution directly to the leaves.

This guide explains what foliar feeding is, how foliar fertilizer works, when and how to apply it, which sprays you can use, and what to avoid during flowering.

What Is Foliar Feeding?

Foliar feeding is a technique where you spray liquid fertilizer directly onto the leaves of your plants. Instead of the roots doing all the work, the leaves can absorb nutrients directly.

Foliar feeding can be particularly useful for delivering micronutrients such as iron, manganese, and zinc. However, it works best as a supplemental treatment rather than a replacement for feeding through the root zone.

How Does Foliar Fertilizer Work?

When you spray nutrients onto the leaves, they can enter the plant through tiny openings called stomata. From there, nutrients can move through the plant's vascular system.

Foliar feeding provides a more direct route than the traditional roots-to-shoots path. The spray solution should also be properly pH-adjusted before you apply it to the leaves.

When Is the Best Time to Foliar Feed Cannabis?

Timing matters when applying a cannabis foliar spray. The ideal conditions are generally early morning or late evening, when temperatures and light intensity are lower.

High humidity can help keep the stomata open and improve absorption, while spraying in excessive heat can cause the solution to evaporate before the leaves absorb it.

Foliar Feeding by Growth Stage

• Seedling: Early morning or late evening
• Vegetative: Early morning or late evening
• Flowering: Avoid spraying
• Late flowering: Avoid spraying

Outdoor growers have less control over temperature, humidity, and light, so timing can be more difficult to manage.

Types of Foliar Sprays

Foliar sprays generally fall into two groups. Some are designed to treat problems on the leaf surface, such as certain fungal issues. Others are absorbed into the plant and transported through its vascular system.

Common types of foliar sprays include:

• Nutrient sprays: Provide nutrients that plants may be lacking.
• Pest control sprays: Help deter or control pests. Neem oil is one example and should only be used during the vegetative stage.
• Growth enhancers: Contain compounds intended to support plant growth.

What Can You Put in a Foliar Spray?

Common ingredients used in foliar sprays include:

• Epsom salts: Provides magnesium and sulfur.
• Seaweed extract: Contains trace minerals and other compounds used to support plant vitality.
• Molasses: Provides carbohydrates that can support beneficial soil microbes when used appropriately.
• Neem oil: Used as a natural pesticide and fungicide.
• Compost tea: Contains nutrients and supports microbial activity.

How to Foliar Feed Cannabis

Before applying a foliar spray, gather your equipment and prepare the solution under suitable conditions.

What You Need

You'll need a pump sprayer, pH meter, measuring spoons, distilled water, and your chosen nutrient or spray product.

Spray in the early morning or late evening to reduce the risk of leaf burn and support absorption.

Mixing the Solution

A basic foliar spray recipe uses 1 gallon of distilled water with 1 teaspoon each of Epsom salts, seaweed extract, and molasses.

Adjust the solution to a pH between 5.8 and 6.2 before spraying.

Spraying the Plants

Hold the sprayer about 6–8 inches from the plant and apply a fine, even mist to the leaves. Cover both the tops and undersides of the leaves, since the undersides contain more stomata.

Avoid soaking the leaves until they drip. After spraying, monitor the plants for the next 24–48 hours and watch for signs of burn or improvement.

How Often Should You Foliar Feed?

For most foliar sprays, once a week during the vegetative stage is generally sufficient. Start with a diluted solution if you're new to foliar feeding and increase the concentration only if needed.

Monitor your plants rather than applying more spray simply because a schedule says it's time. Overapplication can increase the risk of leaf burn and other problems.

Can You Foliar Spray During Flowering?

Foliar spraying during flowering carries additional risks. Sprays can leave residue on developing buds, while excess moisture can increase the risk of mold and mildew.

For these reasons, avoid spraying during flowering, particularly during the later stages. If foliar feeding is necessary earlier in the plant's life cycle, complete it during the vegetative stage whenever possible.

Is Foliar Feeding Effective for Cannabis?

Yes, foliar feeding can be useful when plants need nutrients quickly, particularly when delivering micronutrients. It should be viewed as a supplemental method rather than a replacement for feeding the root zone.

Results depend on the nutrient or spray being used, application conditions, and the plant's needs.

Common Problems With Foliar Feeding

Foliar Burn

Leaf burn can occur when the spray solution is too concentrated or when plants are sprayed in excessive heat or intense light. Start with a diluted solution and apply it during the early morning or late evening.

Mold and Mildew

High humidity combined with wet foliage can create conditions that encourage mold and mildew. Maintain good air circulation and avoid oversaturating plants.

Nutrient Lockout

An improperly pH-adjusted foliar spray can interfere with nutrient absorption. Always check and adjust the pH of your solution before applying it.

Homemade Foliar Spray Recipes

Homemade sprays can be less expensive and allow you to control the ingredients, but they require careful preparation.

Basic Foliar Spray Recipe

Ingredients:

• 1 gallon distilled water
• 1 teaspoon Epsom salts
• 1 teaspoon seaweed extract
• 1 teaspoon molasses

How to mix it:

       1. Combine the ingredients in a spray bottle.

       2. Adjust the pH to between 5.8 and 6.2.

       3. Apply the solution evenly to the leaves.

Wrapping Up

Other commonly used combinations include neem oil with water and mild dish soap for pest control, or compost tea with fish emulsion and kelp extract for nutrient and microbial support.

There you have it—a complete guide to foliar feeding your cannabis plants. It might seem like a lot at first, but once you get the hang of it, foliar spraying can be a quick and efficient way to boost your plant’s health and growth. 

Why not start with high-quality seeds that give you the best foundation for thriving plants? Check out our extensive collection of cannabis seeds and strains at Homegrown Cannabis Co.

Foliar Feeding FAQs

How Often Should I Foliar Feed?

Once a week during the vegetative stage is generally enough for most foliar sprays. During flowering, minimize spraying or avoid it altogether.

What's the Best Time of Day to Foliar Feed?

Early morning or late evening is generally the best time to foliar feed because light and temperatures are less intense.

Can I Use Tap Water?

Distilled or reverse-osmosis water is preferable when preparing foliar sprays because tap water can contain minerals or other substances that may affect the solution.