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Why Does My Cannabis Experience Cal Mag Deficiency?

As discussed, there are three likely reasons your cannabis plant is experiencing cal mag: improper pH levels, poor water quality, and unsuitable soil nutrients. Still, for each of these explanations, there are specific reasons why your cannabis plant may be experiencing a deficiency:

Nutrient Imbalance

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.

Soil That's Highly Acidic or Alkaline

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.

Low Rates of Transpiration

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.

Treated or Soft Water

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.

Sandy or Coarse Soil

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.

Why Does My Cannabis Experience Cal Mag Deficiency

How to Treat Cal Mag Deficiency

With these identification techniques, it should be easier for you to spot cal mag deficiency in weed. More notably, you should be able to identify the direct source of that deficiency.

But how do you resolve these issues?

We’ve laid out a few different ways to ensure your plants are receiving a balanced source of calcium and magnesium. Again, you’ll want to only tackle the issues your plants are running into, rather than all issues at once.

Fixing pH Imbalance

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.

Nourish Your Plant

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.

Ventilate Your Plants

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.

Use Cal-Mag Supplements

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.

Making Calcium-Magnesium Supplements At-Home

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.

Final Word

As you go about resolving your plant’s cal-mag deficiency symptoms, it’s important to keep a close eye on your plants. Honestly, this is essential when growing marijuana as a whole. While these plants can be very resistant, the best buds appear when they’re properly taken care of.