Calcium Deficiency?

Thread starter #1
I have a nutrient deficiency with one of my plants. Details:
Strain AK-47
Soil: Fox Farm Ocean Forrest
PH: 6.5 — 6.7
Light: Apollo Horticulture LED Grow light 400w X 2 (only using 1 atm)
Pot size 4.5 gal
RH% 45-55%
Temp: 78-82 degrees
Indoor only
Have you flushed the soil — Not yet

A week ago I re-potted this plant because it was getting big and I started to notice some browning on the leaves (see picture). I 'THINK' this is a calcium deficiency, but I cannot be sure as the symptoms are easily confused with other problems. I have 3 other plants (1 other Ak-47 and 2 Northern-lights) which were germinated and planted at the same time in the same type of soil (FF) and none show the characteristics seen in this one plant.

All 4 plants are growing fast — my concern with taking any kind of action is; I am not 100% sure what action to take, and I do not want to flood it with nutrients or other stuff before I ask some people who have greater experience with a diagnosis.

For a calcium deficiency I have Dyna-Grow Foliage Pro. My plan to address this problem is to flush the soil with approximately 10 gal of water, measure the run off PH then add a tablespoon of Dyna-Grow to 1 gal of water and water it. I'll use that for several days and see where I stand after a week or more. I realize the leaves with brown spots will not turn green and I'll have to watch newer growth for repeat symptoms. If I need to get some garden lime or some other remedy I can do so with no issue.

The browning on the leaves is more pronounced than the images show. I've never seen this particular problem pop up with my plants. Any further suggestions?

Thread starter #4
Thanks for the reply - I did verify the PH is 6.4 - 6.7 with a meter. I am pretty sure this is a calcium deficiency. As I previously stated I have not seen this particular problem before and in this batch I have 4 plants growing. Two different strains - everything else is the for all 4 however for some reason this one plant is having a problem. Not too sure why this has occurred and I am trying to address it.


420 Member
The reason you see it in one plant, and not the others could be one of a few reasons.

Cannabis strains all have different tolerances, and nutrient requirements. While 1 strain may be fine with a certain level of nutrients, another strain may show signs of nute burn when fed at the same strength, or it may show signs of deficiencies, even though it's receiving the same strength of nutes.

This holds true for plants of the same phenotype as well. These would be identical strains all grown from seed. So on the surface they're the same strain, but genetically they're all slightly different. Think about two siblings in a family. They have the same parents, but one may enjoy rock music, the other might prefer metal.

Plants of the same genotype should not exhibit this varied sensitivity. These would be plants cloned from a mother plant. The mother, and the 2 clones will all have identical genetics, and should all have no problem being fed the same concentrations.
But even in this case, there's always the risk of human error. For example, maybe a nutrient solution wasn't mixed thoroughly, and one clone received higher concentrations than the other. The same holds true in the case of lighting, circulation, etc.. human error can contribute to one genotype receiving more than another..

Addressing the problem is easy.
1. Never panic or worry.
2. Verify proper PH.
3. Rule out pests (This is a quick and easy step for an observant grower)
4. Diagnose the deficiency, which in this case looks like the early stages of Calcium, and supplement the deficient plant.
5. Watch the plant closely to make sure the deficiency symptoms do not advance further.

In many deficiencies, it will permanently damage a leaf, and the problem will be there for the remainder of the grow. But don't worry about that. We're not in it to grow nice fan leaves, the goal is to grow nice buds. So unless a leaf is mangled and completely destroyed, I leave it on for the remainder of the grow. If you run into future deficiencies, it is likely that it will show up on these already damaged leaves, so let them 'take one for the team' and it keeps your other leaves looking nicer, and healthier.
It's definitely a calcium deficiency. Get some Advanced Nutes Sensi Cal/Mag Xtra or a similar calcium supplement. Be careful if you use it during flowering that it has low nitrogen levels. Foliar feed them everyday for 3 days, mix according to directions on the bottle, and incorporate it into your feelings on a regular basis and u should b ok. I'm not sure what u r growing in but adding dolomite lime to your mix also helps with calcium as well as ph. Happy Growing!