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?
@mwhite9829 Thank you.
Usually 5ml per gallon, but it depends on what you buy. Check the label.
@D K My slurrys ppm was 415 & my PH was 6.19
Introduced CalMag & have even more yellowing today @mr.growit
415 PPM is super low for being in flowering. How many days into flowering are you? What nutrients are you giving the plant, at what dose, and what PPM are you aiming for?
@Mr. Grow It I really don’t know much about PPMs… I’m currently 30 days into flowering & I’m using General Hydroponics nutes & the dosage has been:
Wk 1 - .5/.5/.5
Wk 2 - 1/1/1
Wk 3 - 1/.5/1.5
Wk 4 - 1/.5/1.5
I just introduced CalMag in week 4. I have no idea what I should want my PPMs to be at.
Here's what I aim for when in flowering:
Weeks 1-4 - 750-950
Weeks 5+ - 1000-1600 Not sure if you have my book but there is a section on PPM which gives a bit more detail.
I do not but will definitely pick it up. How would you recommend I bring that number up?
Do you offer the book in PDF form?
@AllDay Yes, if you buy off my website, the book comes in both pdf and epub formats. If you're on a mobile phone, I highly recommend using an e-reader app like Moon App to view the epub version since it has the ability to click links in the table of contents. It just makes viewing much easier.