Problem: Signs of a cannabis calcium deficiency can be hard to pin down since calcium deficiencies are often accompanied by magnesium, iron, and other deficiencies. However, some of the major signs of a calcium deficiency are in the leaves which will display dead spots, crinkling, spotting, or small brown spots. Another sign of a cannabis calcium deficiency is new leaves will appear small and distorted with curled tips The insides of the plant and well as the flowers/buds may show signs of decay. Roots may show signs of bacteria and may be dying off or be under developed.
Solution: If the pH of your root zone is off, then your cannabis cannot properly absorb calcium through its roots so the first step is to ensure that you have the correct pH for your growth medium. Learn more about pH and cannabis. Different strains of cannabis tend to have different nutrient problems, but calcium, magnesium, and iron deficiencies often appear together in cannabis. Therefore many growers decide to purchase some sort of Calcium-Magnesium (often called Cal-Mag) supplement for their grow room in case this common deficiency appears. I have listed some available Cal-Mag supplements that I have used along below 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.
