Calcium and magnesium are vital minerals for the growth and development of marijuana plants. They help make the frames, you know, the body skeleton that holds your buds. The plant also needs Cal-Mag to facilitate photosynthesis.
Calcium and magnesium come as Cal-Mag supplements and are on every grower’s nutrient list. The plant needs Cal-Mag in different amounts at different stages.
However, supplementing your plant’s nutrients, including Cal-Mag, is a balancing game. You give them too little, and your plant will suffer deficiencies. You give them too much, and you’re staring at another mayhem.
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Should I Use Cal-Mag Every Watering?
It’s good practice to use Cal-Mag every watering up to the later stages of the plant’s growth. The dosage will, however, be different. When giving Cal-Mag to solve existing deficiencies, use the 5ML per gallon, while when using Cal-Mag to avoid the deficiency, use 1.5ML per gallon.
Stop using Cal-Mag when watering in the last stages of flowering if the plant is in good health. If you continue to supplement Cal-Mag in the later stages of flowering, you risk harvesting harsh buds due to nutrient residues in the buds.
The cannabis plants need calcium and magnesium throughout the growth stages. However, the frequency and dosage of the Cal-Mag supplement are dependent on such factors as the grow medium, the degree of deficiencies, and the water you use in watering.
When using hydro systems with RO water, you will use Cal-Mag supplements more frequently and at a higher dose than when you used tap water. Unlike tap water that has varying levels of minerals in it, reverse osmosis leaves no calcium or magnesium in the water.
When you grow in coco coir, you will need more Cal-Mag supplements than when you use soil as the grow medium. Coco coir is known to lock out calcium, and so it’s essential to supplement Cal-Mag adequately.
RELATED READ: How to Cure Calcium and Magnesium Deficiency in Cannabis
How Often Should You Use Cal-Mag?
Cal-Mag supplements rarely cause nutrient toxicity because the plant needs them throughout the growth phases. Thus, you can use them almost every time you water the plants. However, keep the dosage on the low, at 1.5ML when you’re not supplementing to correct an ongoing Cal-Mag deficiency.
Diagnose your plants. Look that leaves for any signs of calcium and magnesium deficiencies. The degree of the plant’s nutrient deprivation will also influence how often you use Cal-Mag.
Spotted leaves, yellowing leaves, stunted growth are some of the signs to look for when diagnosing your plant for Cal-Mag deficiencies.
However, not every time you supplement Cal-Mag, the plant needed it. Sometimes the problem is pH imbalance or watering troubles. Check the pH before concluding that the yellowing leaves are a result of calcium deficiency.
An imbalance in pH causes nutrient lockout and thus starving the plant of various nutrients. Adding Cal-Mag will not solve your woes if you don’t stabilize the pH.
Does Cal Mag Raise Or Lower pH?
Adding Cal-Mag affects the pH in varied ways depending on the concentration of its components.
Fertilizers that are higher in nitrate nitrogen like Cal-Mag 15:5:15 will increase the pH, while fertilizers that are higher in ammoniac nitrogen as 20:20:20 lowers the pH of the grow medium.
Though adding Cal Mag can affect your pH, you shouldn’t use supplements to bring the pH down. Adding more calcium can lock out other nutes, stressing your plant even further.
Instead of relying on nutrient supplements to shake the pH level in your grow medium, investing in a pH calibration solution kit will help you keep the grow medium within the correct pH range.
And when checking the pH of the grow medium, do not check the meter atop the soil— check the runoff water’s pH because it gives you the real pH in the roots.
RELATED READ: What Causes Brown Spots on Cannabis Plant Leaves?
Should I Use Cal Mag During Flowering?
If you’re using coco coir, then you should use Cal-Mag throughout the plant’s growth. For soil, it is good to add Cal-Mag since they spur photosynthesis, creating enough food to sustain the plant throughout the flowering stage.
Calcium also improves the plant’s defenses against pathogens and helps in the absorption of other minerals like iron and magnesium. When calcium drops, the plant will also be deficient in iron and magnesium.
You should thus ensure all that your plant doesn’t stall in growth and bud development when you can avoid the situation by adding Cal-Mag.
There is a lot of misleading information on the subject of adding Cal-Mag during flowering.
While others believe that supplementing Cal-Mag burdens the buds with nutrient residues that lower your weed quality, it is during flowering that the plant needs the most nutrients.
Most times, if you fail to supplement Cal-Mag during flowering, you’ll see the leaves turning yellow and having brown spots.
Use Cal-Mag so that the plant doesn’t run into deficiency and waste energy healing from the deficiencies.
In conclusion, you should use Cal Mag every watering when you’re growing in coco coir.
In soil, you can still use Cal Mag every watering to keep your plant from wanting the nutrients. However, you can also only use Cal Mag when the plant asks for it.