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Solving Calcium Deficiency in Cannabis

calcium deficiency cannabis

Table of Contents

What Does Calcium Do for Cannabis Plants?

Calcium Deficiency Cannabis is a must-solve problem because calcium is a very important nutrient that is essential to the health and growth of your cannabis plants. It provides structure to the plant and strengthens it against stressors like heat. Additionally, calcium plays a key role in early root development and proper plant germination, while supporting healthy flowering and vegetation. It also promotes vitamin and protein synthesis and is necessary for potassium absorption.

Calcium is a semi-fixed nutrient, which means it will remain within the cell walls unless there is extreme Calcium Deficiency in Cannabis Plants, at which point, it will become soluble. This explains why the symptoms tend to appear in the middle and older leaves.

How to Identify Calcium Deficiency in Cannabis

If your plant has Calcium Deficiency Cannabis, you will notice the problem through bronze or Brown Spots on Cannabis Leaves that, sometimes, appear purple under LEDs. The leaves don’t always yellow, but you might also see some yellowing on newer leaves and fan leaf parts that have been exposed to light.

As mentioned, calcium is a semi-mobile nutrient and moves slowly through the leaves. This means that, after you feed it to your plants, newer foliage might not show signs of deficiency. This includes all the leaves that have been exposed to light recently.

Common Symptoms of Calcium Deficiency

Leaves

The most tell-tale sign of calcium deficiency in cannabis plants is black spots on fan leaves. Most symptoms will appear on foliage that is currently in the vegetative stage and on growing leaves. You might think ‘I don’t have black spots on my fan leaves’, well there are other symptoms. Generally, the leaves might show the following:

  • Crinkling
  • Dead spots
  • Mottling or spotting
  • Small size or distorted shape
  • Stunted growth
  • Curled tips
  • Dying-off

Roots

If calcium deficiency is left to take root in the plant, it may begin to affect the root system in the following ways:

  • Roots begin to turn brown or die off
  • Underdeveloped root systems
  • Bacteria begins to proliferate on roots
  • Weakens roots
  • Roots are vulnerable to slimy root rot

Abnormal Plant Growth

Overall, the plant will show the following signs of deficiency:

  • Slow or under-developed buds and flowers
  • Crinkling young shoots
  • Stunted growth
  • Weak branches are stems that break easily
  • Plant is unable to withstand heat
  • Stems hollow out and decay from the inside

What Causes Calcium Deficiency in Cannabis Plants?

Calcium Deficiency Cannabis is more common in situations where the grower is using filtered or soft water or growing the plants in coco. However, the most common cause of this problem is low pH in the root systems. Generally, Calcium Deficiency in Cannabis is more likely to occur when:

  • You grow your cannabis plants using reverse osmosis (RO) or filtered water. Most tap water contains enough calcium levels to sustain your plants but RO water might not.
  • You grow your cannabis plants in coco coir or a hydro setup without supplementing calcium.
  • The grow medium has a low pH level, which means it is too acidic to allow calcium absorption by the plants, even if the nutrient is available.
  • The soil is not being supplemented with calcium.
  • The grow medium has excess potassium, which can cause calcium lockout.

How Do You Solve Cannabis Calcium Deficiency?

As we have seen, there are multiple causes of calcium deficiency, which means there are also several solutions. The most effective ones you should try are:

Fix the pH

Most cases of Cannabis Calcium Deficiency can be attributed to low pH levels around the root system. Therefore, your first step should be to measure the pH of your grow medium and correct it if necessary. The ideal level will depend on the type of grow medium:

· Soil: 6.2 – 7.0 pH

· Coco or Hydro: 6.2 – 6.5 pH 

If you find that the pH level is not ideal, flush the grow medium and root system with clean, pH’d water to remove all excess nutrient salts. You want to use water containing a proper amount of cannabis-friendly nutrients, including calcium. This should restore normal pH levels and you should soon see the Brown Spots on Cannabis Leaves go away.

Dolomite Lime

If you are growing your cannabis organically and would like to supplement the calcium in your grow medium, you can do so through Dolomite Lime. This compound is an excellent source of magnesium and calcium and can easily be mixed into your grow medium. It corrects the pH because it also has a neutral pH of around 7.0, which is recommended for cannabis growing. Additionally, it will work slowly over several months so you don’t need to worry about replenishing the levels again.

Dolomite Mite
Dolomite Mite is an excellent source of Calcium for deficient cannabis plants

Tips: You can purchase Dolomite Lime online but, if you account for shipping fees, it is cheaper to buy it at a local gardening store.

Cal-Mag Supplement

Lastly, you can treat Calcium Deficiency in Cannabis by supplementing calcium levels in your grow medium through a Calcium-Magnesium (Cal-Mag) supplement. This is an excellent solution because calcium and magnesium deficiencies tend to appear together. After application, you should begin to see healthy new leaves within a week. The older, already-affected foliage might not recover, however.

Plant Problems with Similar Symptoms to Calcium Deficiency

Sometimes, Cannabis Calcium Deficiency can be difficult to diagnose since it is usually accompanied by other deficiencies like iron and magnesium. Some growers also find it confusing because it tends to produce different symptoms of different strains. That said, you can always diagnose calcium deficiency through the tell-tale Brown Spots on Cannabis Leaves.

Final Word on Calcium Deficiency

Cannabis plants will usually absorb as much calcium as you give them as long as the conditions are optimal. Calcium Deficiency Cannabis occurs when these conditions change, such as when the pH is too low or you are growing your plants hydroponically, in coco coir, or using RO water without supplementing calcium. If you notice this problem, you need to flush your soil system and feed your cannabis plants through the suggestions made here. Within no time, your plants should be free of Cannabis Calcium Deficiency.

If you think calcium deficiency isn’t the problem with your cannabis, it could be one of the other cannabis deficiencies.

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Ed Rushford
Ed Rushford
Ed Rushford’s impact on cannabis growing is undeniable. Though he tends to focus primarily on 2 areas, plant training techniques and dealing with disease, pests, and other problems, he has offered many insights into how cannabis plants live and grow. That’s not to say that Ed is unfamiliar with the complete life cycle of cannabis, from seed to harvest, but he uses his widespread knowledge to hone in on the minutia and niche areas of growing cannabis. Ed’s goal is to spread knowledge and allow for everyone to become better growers. While Ed has a particular penchant for the SCROG, Schwazzing and Mainlining techniques in his own garden, he has basically mastered every growing technique which has allowed him to choose the ones he personally favors. When it comes to pests and diseases, Ed draws on his own experiences as a novice grower way back in the day and builds upon his own learning curves to provide comprehensive guidance on dealing with plant problems in a pinch.
Ed Rushford
Ed Rushford
Ed Rushford’s impact on cannabis growing is undeniable. Though he tends to focus primarily on 2 areas, plant training techniques and dealing with disease, pests, and other problems, he has offered many insights into how cannabis plants live and grow. That’s not to say that Ed is unfamiliar with the complete life cycle of cannabis, from seed to harvest, but he uses his widespread knowledge to hone in on the minutia and niche areas of growing cannabis. Ed’s goal is to spread knowledge and allow for everyone to become better growers. While Ed has a particular penchant for the SCROG, Schwazzing and Mainlining techniques in his own garden, he has basically mastered every growing technique which has allowed him to choose the ones he personally favors. When it comes to pests and diseases, Ed draws on his own experiences as a novice grower way back in the day and builds upon his own learning curves to provide comprehensive guidance on dealing with plant problems in a pinch.

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