Do you have Calcium Deficiency in your Marijuana Plants ?

You may notice some spotting on new leaves on your cannabis plants, yellowing between the veins.

These are some of the first signs to watch out for with a calcium deficiency.

One thing marijuana plants love is calcium, and if you're not supplementing with enough of it you will run into issues pretty quick.

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When lacking calcium in your plants, it can also appear to have an iron or magnesium deficiency.

If you are not sure if your plants are getting enough calcium with their nutrient feeding, there is plenty of information here to give you a definitive answer.

Let's check out your plants,

Signs of Calcium Deficiency

  • Upper leaf issues show spotting first
  • Lower leaves curl and twist
  • Yellow, brown spots appear on leaf and tips
  • Stunted growth
  • Flower development is slow
  • Brown or dark spots on leaves
  • Random pattern of spots
  • Stems start to become weak
  • Roots have little development
  • The roots begin to die in extreme cases

Click on image to enlarge,

calcium deficiency marijuana diagram

Image

Why is calcium important to marijuana?

calcium symbol

Calcium is vital for the plant's growth.

It is an immobile nutrient so the plant cannot find the mineral in older leaves to assist in the plant's growth.

Calcium in a marijuana plant helps build the cell walls and assists in growing root systems.

It also helps the plant against heat stress.

This secondary nutrient works alongside magnesium, which is also necessary for healthy plant growth.

Calcium deficiency affects all plants.

For example;

You may have noticed if you grow tomatoes in the summer outside without with calcium you get blossom end rot. According to Wikipedia.

Calcium Deficiency marijuana

Brownish spots appearing on a leaf

Causes of Calcium Deficiency

Here is a list of some of the reasons of lacking calcium

  • Not using enough calcium when growing or any at all
  • Growing hydroponically and not supplying enough calcium to the marijuana plant.
  • Low PH soil (check your soil ph values )
  • Using Reverse Osmosis (RO) water, all minerals are removed.
  • This is the best water, you can use for growing. You must supplement with calcium.

You can also run into Calcium Lockout.

Calcium lockout happens when the ph is below a certain level which causes the grow medium to become acidic which stop's the uptake of calcium by your plants.

Here are some PH values to watch for if they are below these values:

When growing in soil: PH levels of 6.0

Hydro and Soil Less Mediums: PH levels of 5.4    

Calcium-Deficiency-marijuana-leaf

Early signs, yellow spots before they turn brown

How to Fix Calcium Deficiency

If you have determined you are deficient in calcium, then you should start with the following to help your marijuana plants recover quickly.

Flush plants: An essential first step to purge any leftover nutrients

Correct the PH level in water/ nutrients.

The optimal ranges should be in the following markers:

Soil, 6.0 - 6.5 pH range. Hydro or coco coir, 5.5 - 6.3 pH range

Add extra calcium nutrients a little at a time

You could try Dolomite, but a jug of cal mag would do just fine.

Some growers use tap water with great success! Just make sure you over 155 ppm. Most tap water contains calcium and magnesium in small quantities.

Calcium for Marijuana:

Here are some of the popular calcium for your marijuana plants.

Safergro Biomin Calcium can be used for a rapid uptake of calcium in your plants.

It's only a calcium supplement for your plants.

It also provides vital amino acids to the plant and can be used with soil or hydroponically and is 100 percent organic.

calcium-deficiency-cannabis

Late stages of calcium deficiency

Cal Mag for Cannabis:

Botanicare CAL-MAG Plus Plant Supplement is the one, two, three punch for your marijuana.

It covers all the bases.

Like Calcium for one and also magnesium and iron, so you know your plants are getting the optimal amounts of supplements they deserve.

Cal mag plus can be used in all stages of growth from vegetative to transition and flowering.

It does contain some nitrogen as well 2-0-0. So be sure to take into account when using any other nutrients.

Cal Mag Plus has 2 percent nitrogen, 3.2 percent calcium, 1.2 percent magnesium, and .1 percent iron.

This can be used in all types of growing : soil or hydroponic

Hydro Organics Earth Juice Elements Cal-n-Mag Plant Food is specifically designed to treat deficiency of calcium and magnesium with your cannabis plants.

It is also a great supplement for any time of the grow and works great in all growing conditions indoors and outdoors, in soil or hydroponic.

Cal-n-Mag contains 2 percent nitrogen and 3 percent calcium and 1 percent magnesium

Advanced Nutrients Sensi Cal-Mag Xtra Plant Nutrient is an excellent combo supplementation which provides the optimal amounts of calcium, magnesium, and iron.

On top of that amino acids specifically designed for marijuana plants.

It's high on the nitrogen and comes in at a 4-0-0 ratio so take notice when in flower with your other blooming nutrients.

Sensi Cal-Mag is to be used with non-advanced nutrient products as they already had the required amounts of cal mag you need for your plants.

lower leaf curl marijuana

Lower leaves start to curl

Signs of Excessive Calcium

There are times when your plants cannot handle too much calcium.

It doesn’t happen too often, marijuana likes calcium and eats it like candy.

It still can happen so always manage your nutrients accordingly.

Here what to look out for:

  • Leaf wilt
  • Increased uptake of potassium, magnesium, manganese, iron
  • Stunted growth
marijuana leaf wilt

How to correct excess calcium

The easiest ways to resolve this issue is to simply:

Flush plants which is a great first step

Try and use some balanced nutrients.

Dial down the calcium magnesium supplementation.

Try a little at a time until you start to see improvement.

It could be as easy as a tablespoon difference.


Conclusion

When growing marijuana always supplement with calcium.

Look for a cal mag combo nutrient to make sure you have the proper amounts.

Getting the right amount the plants require can be tricky but you should be able to fix it before things become too severe.

Calcium deficiency with marijuana can creep up on your plants so be careful and always keep checking your plants for signs of any nutrient deficiencies.

Have you had an issue with calcium with your marijuana?

Let me know in the comments. 

Grow on my friends.

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4 thoughts on “Do you have Calcium Deficiency in your Marijuana Plants ?

  1. For Hydro proper uptake of Calcium is done with PH of 5.9-6.5. So the PH has to be on the higher end of the PH spectrum (hydro only).
    I had a Cal def. and raised the PH to 6.3 and seemed to clear right up.

  2. Hi my name is vincent this is my first grow and my plant is 6 days old the sides of the leaves are kinda curling up ? What could it be my plant is only about a inch tall and i have it under cfls about 2 inches away from the lights with a small fan about 6 inches high and six inches wide. What can be going wrong im using fox farm soil also. My ph i dont no what it is cause i dont have one and im using tap water from the sink. Help me

    • Hi Vincent,
      Sorry to here about your plant. I would suggest raising the light to at least 8-12 inches away. 2 inches is way to close. Tap water is ok but get yourself a cheap ph meter for like $15 with PH up / down. And shoot for 6.1 – 6.5. your PH levels are key. Your plant probably doesn’t have a calcium deficiency this early on.
      Hope this helps.

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