Thu. Jul 18th, 2024

Growing Weed with Eggshells | DIY CalMag Recipe


When it comes to growing weed plants, providing them with the right balance of nutrients is essential for their overall health and productivity. Calcium and magnesium are two micronutrients that are often deficient in weed plants, leading to stunted growth and lower yields. Commercial cal/mag supplements can be expensive, but did you know that you can create your own nutrient-dense supplement using just a few household items? We will show you how easy it is growing weed with eggshells by making your own DIY cal/mag fertilizer using only eggshells, vinegar, and molasses. Not only is this method cost-effective, but it also allows you to have full control over the quality and composition of the supplement. Let’s dive in and learn how to give your cannabis plants the nutrients they need to thrive.


Understanding the Benefits of Growing Weed with Eggshells

Eggshells may seem like ordinary kitchen waste, but they actually contain a wealth of nutrients that can benefit your cannabis plants. An empty eggshell is composed of 95% calcium carbonate, making it an excellent source of calcium. It also contains other vital nutrients like magnesium and phosphorus. However, simply adding eggshells directly to the soil will not provide immediate benefits to your plants. The nutrients in eggshells are not readily available for absorption by the plants. Therefore, we need to change the chemical composition of the eggshells to make them bioavailable. This is where the DIY cal/mag fertilizer comes into play.


Creating Homemade Cal-Mag Fertilizer from Eggshells

Growing weed with eggshells by making your own Cal-Mag is a simple process that anyone can do with just a few household items. Here’s a step-by-step guide on how to transform eggshells into a nutrient-rich supplement for your cannabis plants:

Step 1: Prepare the Eggshells


After cooking your breakfast, wash the eggshells both inside and out. Allow them to dry in a warm spot for a day or two until they are completely dry. Once dry, crumble the shells into small pieces directly into a dry baking pan. Place the baking pan on medium to high heat and toast the shells until they start to turn brown or black. This process helps change the chemical composition of the eggshells, making them more suitable for plant absorption.

Step 2: Grind the Eggshells into a Fine Powder


Once the toasted eggshells have cooled, use a coffee grinder or a mortar and pestle to grind them into a fine powder. This will ensure that the nutrients are evenly distributed and easily accessible for your plants. Transfer the powdered eggshells to a large Bottle.

Step 3: Create the Calcium Solution


Place the powdered eggshells in a large glass jar and cover them with vinegar. You can use apple cider vinegar or any other vinegar you have available. Start by adding the vinegar slowly, as it will cause a chemical reaction that will create fizzing. The reaction will continue for a few hours, so it’s best to leave the jar overnight or until all the fizzing has stopped.

Step 4: Ferment the Mixture

After the fizzing has stopped, transfer the mixture to a jar with a tight-fitting lid and let it sit for a couple of days to ferment. This fermentation process further breaks down the eggshells and enhances the nutrient availability. Once the fermentation is complete, filter the liquid through a fine-mesh sieve into another jar, discarding any remaining solids.

Step 5: Add Molasses and Water


The resulting liquid is a highly concentrated calcium-based solution. To make it suitable for plant use, you will need to dilute it and add magnesium separately. Add one tablespoon of the fermented eggshell solution to a bottle, followed by one tablespoon of unsulphured organic blackstrap molasses. Then, add one gallon (3.8L) of water to the bottle and shake well. Check the pH of the mixture and adjust it to 6.5 using vinegar, sodium hydroxide, or pH-up or down solutions. Your homemade cal-mag fertilizer is now ready to be used on your cannabis plants!

Using Homemade Cal-Mag Fertilizer on Cannabis Plants

Now that you have your homemade cal-mag fertilizer, it’s time to use it on your cannabis plants. Here are some guidelines on how to apply the fertilizer for optimal results:

Soil Gardens:

  • Use 1 teaspoon of the homemade cal-mag fertilizer per gallon of water.
  • Apply the diluted solution with every watering as part of your standard fertilizer program.

Accelerated Formula:

  • Use 2 teaspoons of the homemade cal-mag fertilizer per gallon of water.
  • Apply the diluted solution with every watering for faster growth and increased nutrient uptake.


  • Use the homemade cal-mag fertilizer with your preferred hydroponic formula.
  • Ensure that the nutrient levels are within the desired range: Nitrogen (N) 160-250 ppm, Magnesium (Mg) 45-75 ppm, Calcium (Ca) 160-280 ppm, Iron (Fe) 2-7 ppm.

Remember to monitor your plants’ response to the fertilizer and adjust the dosage accordingly. It’s always a good idea to start with a lower concentration and gradually increase it as needed.


Bonus Tip: Growing Weed with Eggshells as Seedling Trays

Eggshells can also serve as natural and biodegradable seedling trays, reducing the need for plastic pots or trays. Here’s a simple method to start your weed seedlings in eggshells:

Step 1: Prepare the Eggshells

Take an egg and gently tap the pointy end with a teaspoon to create a small opening. Peel away a small amount of the shell to open up the seedling pot. Rinse out the eggshell gently, removing any remaining membrane or yolk.

Step 2: Fill the Eggshells with Soil

Place the eggshell back in the egg carton with the larger hole facing up. Fill the shell three-quarters full with soil using a teaspoon or tablespoon. Create a small hole in the middle of the soil using a small tool, such as a small screwdriver. Place the cannabis seed directly into the hole and cover it with some more soil. Water the seedling lightly using a tablespoon or a similar implement.

Step 3: Transplanting the Seedling

When it’s time to transplant, gently tap the bottom of the eggshell with a spoon until it cracks. Peel away the cracked shell to reveal the seedling’s root system. Now, you can easily transplant the seedling, including the eggshell, into a larger pot or directly into the soil.


By harnessing the power of eggshells, vinegar, and molasses, you can create your own nutrient-rich cal-mag fertilizer at home for your cannabis plants. This DIY method not only saves you money but also allows you to have full control over the quality and composition of the supplement. Remember to adjust the dosage and monitor your plants’ response to ensure optimal growth. Additionally, using eggshells as seedling trays adds an eco-friendly touch to your gardening practices. Give your cannabis plants the nutrients they deserve and watch them thrive with this homemade solution. Happy growing!

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