Molasses as a Fertilizer for Cannabis

Molasses, a thick, dark, and nutrient-rich byproduct of sugar production, has become a popular supplement in the cannabis gardening world.

It offers a range of benefits for cannabis plants, from improved nutrient uptake to enhanced flavors and aromas in the final product.

In this article, we'll explore the basics of molasses and why it's an essential addition to any cannabis grower's toolkit.

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The Natural Advantage

In recent years, many cannabis growers have embraced natural supplements to promote plant health and growth. These organic additives work in harmony with the plant's natural processes and the surrounding environment, reducing the need for harsh chemicals and synthetic fertilizers.

Molasses, with its rich nutrient profile and ability to support beneficial soil microorganisms, is a prime example of how natural supplements can give your cannabis plants a healthy and sustainable boost.

While molasses helps your plants make better use of available nutrients, it also provides them with a range of essential vitamins and minerals. By incorporating molasses into your cannabis garden, you're not only nourishing your plants but also promoting a thriving ecosystem in the soil that leads to more robust and productive growth.

Molasses For Cannabis as a Fertilizer

What is Molasses?

Molasses is a thick, sweet syrup produced during the sugar refining process from sugar cane or sugar beet. There are different types of molasses, which vary in color, flavor, and sugar content. The three main kinds are:

  1. Light molasses: Also called mild or Barbados molasses, light molasses is produced after the first boiling of sugar cane or sugar beet juice. It has a light, sweet flavor and a light amber color. It is commonly used for baking and as a sweetener in recipes.

  2. Dark molasses: Dark molasses is obtained after the second boiling of sugar cane or sugar beet juice. It has a stronger flavor and darker color than light molasses. Dark molasses is used in recipes that require a more robust flavor, like gingerbread cookies and baked beans.

  3. Blackstrap molasses: Blackstrap molasses is produced after the third boiling of raw sugar cane juice or beet juice, and it is the most concentrated and nutrient-rich form of molasses. It has a strong, bitter flavor and a very dark color. It's also high in minerals, such as iron, calcium, magnesium, and potassium, as well as vitamins like B6 and niacin.

For use with weed plants, I recommend using unsulphured molasses. Unsulphured molasses is made from sun-ripened sugar cane and does not contain sulphur dioxide, a preservative that may be harmful to plants.

Transform your compost tea game with the all-natural garden elixir, organic molasses! With a deep, rich flavor, our organic food-grade molasses is the perfect addition to your compost tea, feeding the essential bacteria and fungus that drive your microbial extraction process. 

With its heat-resistant properties, our molasses guarantees consistent, flavorful results every time.

Sweet and Potent Source of Nutrition

When it comes to supporting the health and growth of your cannabis plants, molasses is truly a powerhouse of nutrients. This sticky, sweet substance is packed with essential elements such as potassium, calcium, magnesium, iron, and various trace minerals that plants need to thrive.

Let's take a closer look at these nutrients and how they contribute to the overall health and growth of your cannabis plants.

The Nutrients in Blackstrap Molasses

Molasses, particularly blackstrap molasses, contains a variety of nutrients that can be beneficial for plants. Some of the primary nutrients found in molasses are:

  1. Carbohydrates: Molasses is rich in carbohydrates, primarily in the form of sucrose, glucose, and fructose. These sugars serve as an energy source for beneficial microbes in the soil, which can help improve soil structure, nutrient availability, and aid in plant development.

  2. Minerals: Molasses is high in essential minerals such as potassium, calcium, magnesium, and iron. These minerals contribute to various plant functions, such as cell development, enzyme activity, and photosynthesis.

  3. Potassium: It plays a crucial role in regulating water balance, nutrient transport, and enzyme activity in plants. It also contributes to the overall strength of the plant, supporting the growth of thick stems and healthy roots.

  4. Calcium: It is necessary for the development and structure of cell walls, as well as for various enzymatic and hormonal processes. Calcium also helps regulate the uptake of other nutrients by plants.

  5. Magnesium: It is an essential component of chlorophyll, the green pigment responsible for photosynthesis. Magnesium also aids in the activation of various enzymes and the synthesis of proteins in plants.

  6. Iron: It is a vital component of several enzymes and proteins involved in photosynthesis, respiration, and nitrogen fixation. Iron deficiency in plants can result in chlorosis, or yellowing of leaves.

  7. Vitamins: Blackstrap molasses contains some B vitamins, such as B6 and niacin. These vitamins play a role in plant metabolism, enzyme activity, and enhance beneficial soil bacteria.

Timing is Key: Using Molasses in Late Flowering

While molasses can be beneficial throughout your cannabis plant's life cycle, its application during the late flowering stage can be particularly advantageous.

This critical period in your plant's growth is when buds are maturing, and the development of taste and aroma becomes paramount.

By using molasses during this stage, you can help your plants reach their full potential and produce top-quality flowers with outstanding flavor and fragrance profiles.

Feeding Your Cannabis: Quantity, Frequency, and Application

A general guideline for feeding molasses to cannabis plants is to use 1 to 3 tablespoons per gallon of water or fertilizer solution. This range allows for flexibility, depending on your plant's needs and stage of plant growth.

Start with a lower amount and gradually increase it based on how your plants respond.

How Often to Use Molasses on Your Plants

While there isn't a one-size-fits-all answer to how often you should use molasses on your plants, a good rule of thumb is to apply it every 2-3 weeks during the vegetative stage, and then more frequently during the flowering stage, particularly during the late flowering phase when plants need an extra nutrient boost.

Remember, it's essential to monitor your plants closely and adjust the frequency based on their health and growth. If you notice any signs of nutrient burn or other issues, dial back the frequency or quantity of molasses until your plants recover.

Watering Solution or Foliar Spray?

Molasses can be added directly to your watering solution, ensuring it's thoroughly mixed before applying it to your plants. This method allows for easy and even distribution of nutrients and helps support the soil's microorganisms.

Alternatively, you can use molasses as a foliar spray by mixing it with water and applying it directly to the leaves. This method offers quick nutrient absorption and immediate availability but comes at the cost of covering your plants in sticky residue.

We prefer to feed plants with molasses directly into the soil.

Bigger Buds and Increased Trichomes: Myth or Reality?

While molasses can contribute to overall plant health and soil quality, it is not a direct factor in increasing bud size or trichome production.

Molasses mainly provides an energy source for beneficial microbes in the soil, which in turn can enhance nutrient availability, leading to better plant growth. The minerals and vitamins in molasses also contribute to various plant functions.

To encourage bigger buds and increased trichome production, consider the following factors:

  1. Genetics: The genetics of the plant play a significant role in bud size and trichome production. Select strains known for producing larger buds and a higher concentration of trichomes.

  2. Light: Adequate light is essential for bud development and trichome production. Ensure your plants receive the appropriate light spectrum, intensity, and duration for their growth stage.

  3. Nutrients: Proper nutrient management is crucial for plant health and bud development. Focus on providing the right balance of macronutrients (nitrogen, phosphorus, and potassium) and micronutrients (such as calcium, magnesium, and iron) throughout the plant's growth cycle.

  4. Environmental factors: Temperature, humidity, and airflow also influence bud size and trichome production. Maintain optimal environmental conditions for your plants to ensure healthy growth and development.

  5. Pruning and training techniques: Implementing pruning and training methods, such as topping, low-stress training (LST), or the Screen of Green (SCROG) technique, can help maximize bud development and overall plant yield.

While molasses can contribute to better soil quality and overall plant health, it is not a direct factor in increasing bud size or trichome production. A combination of proper genetics, lighting, nutrients, environmental conditions, and cultivation techniques will have a more significant impact on bud and trichome development.

Sweet Alternatives: Comparing Sugars for Cannabis Cultivation

Let us explore the world of sugars and their potential benefits for cannabis plants. Several sugar sources can be used as supplements in cannabis cultivation, including molasses, honey, corn syrup, beet juice and agave nectar.

Let's dive into the world of these sweet alternatives and find out which sugar is best for your cannabis plants.

Molasses vs. Honey, Corn Syrup, and Agave Nectar

Blackstrap Molasses is a popular choice for cannabis growers, as it contains a mix of sucrose, glucose, and fructose, along with essential nutrients like potassium, calcium, magnesium, and iron. This combination of sugars and nutrients makes it a potent supplement for your cannabis plants.

Honey, another natural sugar source, contains primarily fructose and glucose. While honey also has some nutrients, it lacks the mineral content found in molasses. However, it can still benefit cannabis plants, as it feeds beneficial soil microbes and may help with overall plant health.

Corn syrup, on the other hand, is a highly processed sugar source that contains primarily glucose. While it can provide some energy to the soil microbes, it lacks the nutrient content of molasses and honey. As a result, it may not be as beneficial for cannabis plants.

Agave nectar is another alternative that has gained popularity in recent years. Like honey, agave nectar is rich in fructose, but it also contains some sucrose and glucose. Although agave nectar may offer some benefits to cannabis plants, it lacks the mineral content found in molasses.

The Sweetest Choice: Which Sugar is Best for Cannabis?

When comparing these sugar sources, blackstrap molasses stands out as the most promising product for cannabis cultivation due to its diverse sugar content and rich nutrient profile. While honey, corn syrup, and agave nectar can offer some benefits, they don't provide the same level of nutrients and minerals as molasses.

It's important to remember that using sugar supplements in your cannabis cultivation should be done in moderation and as part of a well-rounded nutrient program.

Molasses Flush: A Sweet Finishing Touch

The Sweet Science of Molasses Flush

As we wrap up our journey through the world of molasses and cannabis cultivation, let's discuss the concept of a molasses flush and its benefits.

A molasses flush is the process of using molasses to help remove excess nutrients and salts from the growing medium while enhancing the aroma and taste of your buds. This sweet finishing touch can give your cannabis plants the extra boost they need to reach their full potential.

How to Perform a Molasses Flush and When to Do It

Performing a blackstrap molasses flush is quite simple.

During the last two weeks before harvest, mix 1 to 2 tablespoons of molasses per gallon of water, and use this solution to water your plants.

This will help break down and remove the salts in the growing medium, ultimately improving the root environment.

As a result, your plants will be able to uptake nutrients more efficiently and produce more terpenes, enriching the aroma and taste of your buds.

Conclusion: Reaping the Sweet Benefits of Molasses

In conclusion, using molasses for cannabis offers numerous benefits, from providing essential nutrients to enhancing the aroma and taste of your buds. When used carefully and in moderation, molasses can be a valuable addition to your nutrient program.

I encourage you to experiment with molasses and monitor your plants for optimal results. By paying close attention to your plants and adjusting your molasses usage as needed, you'll be well on your way to growing healthy, robust cannabis plants with the help of this sweet, natural supplement.


  1. Paudel, Gopal, et al. "Effect of Molasses and Organic Fertilizer in Soil Fertility and Yield of Spinach in Khotang, Nepal."

  2. Weedmania420. (n.d.). "Can You Use Molasses During Flush?" Weedmania420.

Author Biography | Christopher McDonald

Christopher McDonald, founder of Happy Hydro and avid gardening enthusiast, is devoted to revolutionizing sustainable gardening. As an authority in plant care with over 20 years of experience, Christopher balances leading his thriving company with tending to his lush garden. In his free time, he relishes exhilarating backpacking trips, psychedelic journeys, and cherishing moments with his family.

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