Cal-Mag stands for Calcium and Magnesium, two of the macronutrients that are rarely discussed when we talk about plant fertilizer, but they are critical for plants. You can buy Cal-Mag fertilizer to add to your regular fertilizer, or you can buy fertilizer that contains calcium and magnesium. Which option is better and do you need either one?
If calcium and magnesium are so important to plants why are they not included in all fertilizer? It is more complicated than you think.
