A Cal Mag overdose can completely ruin your cannabis grow if you don’t act quickly and work to rectify the situation before the damage is done. As soon as you notice the symptoms, you only have a few days to be able to address the situation and fix it! Thankfully when you know what you’re looking for, cal mag overdose in cannabis is pretty easy to identify!
What Is Cal-Mag Overdose In Cannabis?
Cannabis plants need a variety of nutrients to ensure they can grow, reach the flowering stage and eventually yield cannabis buds. Some of these nutrients include Magnesium, Nitrogen, Calcium, and a few others! But just like anything, too much of something good or not enough of something good can lead to issues.

Cal Mag stands for Calcium and Magnesium. Both of these nutrients are important to the overall growth of cannabis plants. That being said, if your plant has too much of either of these nutrients, it can be detrimental to the overall health of your plant.
If you have too much of a nutrient in plants, this is referred to as an overdose. So a cal mag overdose is simply having too much calcium and magnesium and in turn, it harms your cannabis plant.
Read our guides on Nitrogen Deficiency and Potassium Deficiency in cannabis!
Signs Of Cal-Mag Overdose In Cannabis
When your cannabis plant has too much calcium and magnesium, it will begin to become sick and will display a handful of signs which indicate this decrease in health.
- Curling and clawing leaves
- Leaves shriveling in size
- Discolored edges of leaves (brown, gray or rust colored)
- Leaves falling off
How To Fix Cal Mag Overdose In Cannabis:
Although cal mag overdose can kill your cannabis plants, if you act quickly enough, you should be able to turn it around and get your cannabis plant back to full health and get a successful yield!
When you first notice signs of the calcium or magnesium overdose, you need to act quickly because the clock is ticking.
Once you’ve identified that it is a cal mag overdose, you need to immediately stop giving any additional calcium or magnesium products to your plants. Whether it’s nutrients or other feeding products, your plants are struggling with the current amount of nutrients, so they definitely don’t need anymore.
Continue to water and even consider adding a little extra water to help flush the excess nutrients out of your plants system. Overwater them for a day or two to ensure that your plants clean out their systems and are back to full health.