When it comes to nutrients, N, P & K love the limelight! It’s easy to overlook calcium and magnesium. Don’t do this – they’re both macro nutrients. Without them, plants won’t survive. The good news is, it’s simple to add calcium and magnesium. A good ol’ CalMag will do the trick. In fact, adding CalMag is as a quick fix for most common deficiencies, since most CalMags also contains iron and nitrogen.