Doing research I thought I learned that yellowing leaves means nutrient deficiencies. A couple weeks ago I had several yellow leaves & come can find out my partner was still using the veg formula into flowering. We made the adjustment & we still have yellow leaves. What do we need to do?
We feed, feed, water, feed, feed, water. Could this have something to do with the problem?



Looks like it needs some magnesium. Do you give it calmag? I would check your soil pH and PPM also by doing a slurry test and report back your numbers.
@D K I actually don’t give it calmag. Read somewhere you don’t need it in soil… Was that inaccurate? I don’t have a ppm meter but can get one.
@AllDay Yes, cannabis needs both calcium and magnesium. Most base nutrients don't seem to have enough in it. @D K gives some good advice there to check the pH and PPM as well.
Cannabis loves calcium and magnesium. I would pick some up and give it a try to see if things improve. If you have some plain Epsom salt on you, give that a try with your next feeding at a TBL per gallon, but definitely get a ppm and pH meter to keep an eye on your numbers. All plants have different needs.
@D K How much Calmag should I use & just mix it in water?