In this guide we will cover how to diagnose a calcium deficiency correctly, and how to fix the problem. Many growers will rush to assume a cannabis plant problem is calcium deficiency. Don’t rush, make sure you’re right in your diagnosis, so you can treat the plant for the issues it is having.
- 1: Your medium does not have enough calcium in it that is available to your plant.
- 2: The PH of your medium is off, and needs restoring so Calcium is within the correct range.
When growing cannabis in hydroponic setups like DWC or coco, you are more likely to experience a calcium deficiency. This is because calcium will be best absorbed by your plant when the medium is at 6.0 – 6.2 ph. The optimum pH used in hydroponics, is 5.8, so sometimes, calcium can be slightly out of range.
You are unlikely to see a deficiency if you’re growing outdoors. But indoor growers will usually see signs of calcium deficiency around 2 or 3 weeks into the flowering cycle.
If you’re unsure of any deficiency, ask for help in our cannabis growers forum, and get advice from experienced growers. Do not be afraid to ask for help.
If you have any questions about calcium deficiency in a cannabis plant, then feel free to ask for help in our cannabis growers forum
Knowing this, you can help prepare for your next grow, and supplement a little more calcium, just as you flip the light to flower cycle.
Time will be needed for the microbes in the medium to break the nutrients down and make them available to the plant. It is better to try and offer the plant more calcium as they get older.
When calcium is at optimal levels in a cannabis plant, it will remain in the cell walls. When there is a deficiency, it will dissolve and become mobile, as the plant tries to move it to where it’s most needed. This means, when a calcium deficiency in a cannabis first sets in, you will see changes in the middle, and older growth of the plant.
Calcium deficiency in a cannabis plant will affect the uptake of nutrients. Diagnose a cannabis plant problem, and get help in our cannabis growers forum
CaliMagic is Well Suited For Hydro, Coco Coir, or Soil
You can buy Dolomite Lime online, but with shipping, it’s almost always waaaay cheaper to pick up a bag at a home improvement or gardening store such as Lowes, Home Depot, gardening centers, etc. If possible, try to get a finer grade of dolomite compared to something that is more coarse.
Dolomite is a good source of calcium and magnesium and can be mixed with your soil. The great thing about dolomite is it works slowly over the course of a few months.
Calcium Deficiencies Appear on New or Actively Growing Leaves
- Grower is using filtered or reverse osmisis (RO) water to feed plants – the amount of calcium found in tap water varies, but some tap water has enough calcium to prevent calcium deficiencies
- PH is Too Low – If grow medium is acidic (below 6.2 pH, Calcium can get locked out even if the Calcium is physically there)
- Growing cannabis in hydroponics or coco coir without supplementing extra Calcium (it’s recommended to use a Calcium supplement in hydro or coco)
- When growing in soil that hasn’t been supplemented with calcium (usually from dolomite lime)
- Too much potassium can also sometimes cause the appearance of a calcium deficiency
- Outdoors – calcium deficiency is more likely to appear in acidic soil (below 6.2 pH)
Found near the top of the plant under the light
To supplement with extra Calcium… (it’s very rare to give a cannabis plant too much calcium, however, too much calcium can lock out other nutrients so don’t go overboard)
Listed below are common cannabis Calcium supplements, along with some general information about each one. After supplementing with Cal-Mag and correcting the pH, you should expect to see new healthy growth within a week. Remember, the old leaves will probably not recover, but new growth should be green and healthy.
Calcium moves relatively slowly through the plant (it is a semi-mobile nutrient), which means it tends to “stay put” after it’s been given to a leaf. It tends to show up on leaves that are actively growing and getting some amount of light.
Calcium deficiencies cause tiny brown spots that appear on new and middle growth. Learn how to fix this problem for good!