DIY Calcium Phosphate for creating DIY CalMag+

DIY Calcium Phosphate for creating DIY CalMag+

**Note: I didn’t make this recipe, I’m just sharing it to help my fellow growers! Original poster: Emmie from**

Everyone knows you can easily add magnesium to your plants using either Epsom salt or molasses. Most people are left needing to buy a calcium supplement because finding a source of calcium for fertilizer is a little more difficult. It also takes more time to prepare than simply adding Epsom salt or molasses to your water. Once you make the calcium phosphate, you can add it to your water with either molasses or epsom salt to create CalMag+.


  • Dozen egg shells
  • Apple cider vinegar
  • Molasses or epsom salt

Before you get started

Before you get started, make sure your egg shells are thoroughly washed and the membrane inside is removed. Let them dry overnight before continuing. Once your shells are clean and dry, crush them up in your hands so they’re in small pieces.

Creating Calcium Phosphate

For the next part, you’ll need a frying pan. Heat the egg shells in the frying pan on medium heat until most of the shell pieces turn brown, even black with a little white. This will take roughly 5-10 minutes to achieve. The heating process changes the shells; the burned ones will supply the calcium and the white ones will supply the phosphorus. **WARNING: the burnt egg shells have an unpleasant odor**

Next, let the burned shells cool down before using a coffee grinder to turn the shells into a fine, dust-like powder. This makes it easier for the apple cider vinegar to break down the shells. Make sure to measure out the amount of shell powder before adding it to a jar. You’ll want to place the jar into a sink for the next part because it will fizz considerably. Add in 5 parts apple cider vinegar to the 1 part egg shell powder. Once the fizzing has mostly stopped, you can seal the jar up and ferment for 20 days. After the 20 days, your calcium phosphate is ready to use. Simply, filter the mixture into another jar for storage.

How to create your DIY CalMag+

To create your own DIY CalMag+, simply add 1 Tbsp Calcium phosphate & 1 Tbsp of either Molasses or Epsom salt to a gallon of water.

How to use DIY CalMag+

Add 2ml/L of water to create a foliar spray, solution to correct deficiencies, or as a regular part of your feeding schedule. Repeat after one week, if necessary.

Let me know your thoughts in the comments. Don’t forget to subscribe to my blog at the bottom of the page. Feel free to follow me on social media:
Instagram @marijuana.mama_420
Facebook @420.Mama.Grows
Pinterest @marijuana_mama420
Twitter @MarijuanaMama42

Marijuana Mama 420

One thought on “DIY Calcium Phosphate for creating DIY CalMag+

  1. Be careful with the vinegar, something like that could really jinx your ph levels pretty easily IMO. Just go to a plant nursery and get some dolomite limestone plus some organic bone meal and mix with your soil before you plant your seed, those should have all the cal/mag/phos your plant needs for cheap. Just dose up the soil good then you can add various teas and such as/if needed during the grow.

Leave a Reply

Your email address will not be published.

%d bloggers like this: