Brown spots yellowing leaves

[Diesel200034]

Ok this is my first grow all white widow photos was good then 2 weeks into flower was getting brown spots on leaves on just 1 plant . I flushed with ph 6.5 and took nutes down had alittle tip burn I was running half strength fox farm trio once week and water every other sometimes not only if dry . Now got lot of dead leaves and spots got worse I did cal mag thought was calcium deficiency and no luck so back nutes to 1/4 strength and it’s spreading to my other 2 plants . Please help lol .also I’m in soil temps 69 to 75 humidity 55% image widget

[dilvish]

how much cal mag did you use...you need one teaspoon per gallon and flush the plant with it in a proper nutrient mix making sure the PH is above 6.2. it definitely looks like a calcium deficiency. Have you calibrated your PH tester? the PH level may be way off if you are using a method that isn't accurate.

Unless you are using way too much, the plants rarely get too much calcium so add it for the next few waterings and don't scale back nutrients because of a problem. Typically if you are measuring and adding the correct amounts at each watering the issue isn't the nutes, it's the PH level and possibly overwatering.

[Diesel200034]

I did give them 1 tsp per gallon of cal mag seemed to help then got worse quick . I asked a buddy and he thought was nute burn that’s when I back off nutes and flushed , my run off from flush was low like 6.0 . I do have a meter but I can try and get more solution and re calibrate it to make sure . And thank you for info about nutes I didn’t know not to back them off lol . I really do appreciate the help I’ll start them back on calmag 1tsp and calibrate my meter to make sure .

[OldManGrower]

6.0 is too low for soil. You have nutrient lockout due to low PH. Water with 7.0 PH and check your runoff. The runoff needs to be in the mid 6's.

[dilvish]

Yes makes sure your PH readings are accurate...the cal mag is pointless unless the PH is above 6.2. I suspect the PH is way off and you are likely overwatering maybe? That's something to consider too.

I have a fairly cheap PH meter myself and I didn't calibrate it on my last grow...although the grow turned out good, when i went to calibrate it for tis new grow it was off by 2 full points. Generally speaking I allow for some variance but usually no more than 0,2 to 0,5 so 2 whole points was not good!

[Ckbrew]

The crispy dry leaves in the last pix says to me the plant is eating itself to stay alive, so nutrient problem- most are Ph related, might be a root problem, is it over watered?. The brown spots look like calcium deficiency. If you correct calcium, the damaged leaves will not make the brown patches heal. Those are the ones I would prune first. Are you using a Ph meter? My experience was that they drift and need to have calibration checked frequently. Such a drift wound up causing some issues for my plants at one time. I now check calibration before each use.

[Diesel200034]

Ok I’m heading to store to get solution to calibrate my meter , also I water twice a week just water and nutes once week so mon nutes we’d and Friday water 4 cups and give them couple sprays with water bottle almost everyday is this too much water ? Should I not do foliage spray ?

[dilvish]

Cannabis likes humidity but spraying can have some dire outcomes. The plant gets all it needs from the pot watering. If humidity is 50-60% you shouldn't need to spray anyway. As far as "four cups" that may not be enough for one plant so make sure they get a good soaking and have good drainage. 10% runoff is about right. Underwatering could be one of the reasons you have a problem. Having said that, at those temps the soil isn't going to dry out quickly so you may be okay.

[Diesel200034]

I recalibrated my meter was reading over .5 off so I’m guessing this was the cause so when I was feeding it was under 6.0 when I thought was around 6.5 . But thank you for advice on spraying I will pull back on spraying all the time . Around how much water do you think in 4 gallon pots like 8 cups ? I don’t get that much runoff at all with the 4 cups

[dilvish]

If you aren't getting any run off using 4 cups then definitely need more. there should be about 10% runoff. read some more articles on watering practices. Don't be afraid to give the plant a good soaking...just ensure it dries out within a few days, meaning temps should be Between 75 - 85 F during veg

[Diesel200034]

thank you guys again for the advice .Ok when I watered my run off was still very low. So I flushed with about 2 gallons a piece at around 7.0 and my run off I got up to 5.7 is the highest I got . I don’t know how soil got so acidic . I don’t really know what to do they are in 5th week of flower and buds aren’t really filling out and still having dead leaves and yellowing

[dilvish]

are you testing the PH of the water going in or just coming out? thats important. If the PH was off during the majority of the grow then yes the plants are not absorbing the nutrients and likely not getting enough water. At 5 weeks into flower there really isn't much else you can do unless the PH is properly corrected and the watering as well. once you control that then start adding bloom nutrients as recommended by the manufacturer and dont cut back

[Diesel200034]

Yes testing both ways I flushed with 7.0 to try and bring it up and tested runoff was 5.7 at highest and ppm was 170 going in and run off was 800-1000 ppm