Cal Mag Deficiency: How to Spot and Restore Plant Health

Calcium magnesium deficiency in cannabis is a big reason your plant may struggle with cal mag. This usually occurs when there’s a lack of nourishment in the soil. On top of this, you’ll want to ensure your plants are receiving a stable amount of sodium, potassium, aluminum, and manganese.

A balance of all these nutrients is essential to promote the health of your plant cells. If plant cells are unhealthy (for these reasons), you’ll likely notice stunted or slow growth in the roots. Furthermore, your plants may be left oversaturated, leading to atypical shoot and apical bud growth.

If your plants develop curled leaf edges or leaves with brown/yellow spots, they’re likely struggling with magnesium and calcium deficiencies.

Such instances are likely to occur in highly acidic soil, as plants in these conditions find it difficult to absorb calcium and magnesium. However, if your soil is highly alkaline, there’s also a chance the phosphate ions are directly reacting to the magnesium and calcium.

In order to garner the best for your plant’s health, you’ll want to ensure your pH levels range from 6.5 to 7.5.

Lower transpiration rates occur when plants aren’t receiving proper water evaporation to their leaves and flower pores. This naturally leads to nutrient deficiencies as the plant cannot transport these nutrients effectively.

There are a few reasons why a plant may be struggling with transpiration rates, including:

• Chilly weather
• High humidity
• Insufficient watering
• Still air

We recommend taking a closer look at your plant’s environment to ensure all these elements are sufficient.

When it comes to watering, you’ll want to keep an eye out for two separate occurrences that may be causing deficiencies.

The first is treated water which some farmers collect from rainfall or the tap. While on the surface it may seem ideal to treat this kind of water, it can actually strip it away of calcium and magnesium. In turn, you’ll want to avoid reverse osmosis or distilling your plant’s water supply.

The second is soft water which some farmers opt for simply because it does effectively keep plants alive. Still, the difficulty with soft water is it comes with lower pH levels (in turn, lower magnesium and calcium levels).

However, that’s not to say you should use hard water as this comes with pH levels too high for proper cannabis nutrients.

It’s important to also consider the type of soil you’re using as your plant’s medium. If you’re using sandy and coarse soil, it’s likely not providing your plant with enough calcium and magnesium. In turn, you’d rather use clayey or loamy soil.

As mentioned, your pH levels should be anywhere between 6.5 to 7.5. If you’ve noticed your pH levels are too low, you can use some lime to reduce the acidity of your soil. Vice versa, if pH levels are too high, you can add gypsum or bone meal.

Before you make (and as you go about) alterations, it’s worth using a testing tool to check the pH levels within your soil.

Plants that aren’t receiving enough calcium and magnesium through their environment can always get these nourishments through fertilizer. If your plants are already struggling with calcium and magnesium, it’s best to flush the plants with pH-neutral water and then use a more balanced formula.

If your plants are struggling with cal mag deficiency due to low transpiration rates, it’s important to ensure they’re receiving the proper airflow. For this, make sure your plants are in a well-ventilated area where the air is continuously moving. From there, you’ll also want to ensure the plant is receiving consistent water to ensure your transpiration rates are never too low.

Gardening stores offer products that come with pre-mixed supplements. While this can be an easy fix, it’s vital you pay attention to the varied serving sizes and ensure you’re buying the right one for your plant. With that, be sure to always follow instructions from the manufacturer as such supplements can worsen your plants when misused.

If your local store doesn’t carry cal-mag supplements (or you simply prefer a DIY approach), you can always opt to make calcium-magnesium at home. The best way to do so is by mixing Epsom salts with calcium nitrate in a 1:1.5 ratio. More specifically, for every gallon of water, you’ll want 4.5 grams (0.15 ounces) of Epsom salt and 6 grams (0.2 ounces) of calcium nitrate.