HELP! Plants yellowing too soon!?

[Sdubus10]

Hi guys, this is my first post here but I've gained a ton of knowledge from this community and figured it may be my best bet at getting answers!

Here's the problem and my setup! (long post but I want to include as much of the details as I can)

PROBLEM- I've got 4 plants that are 5.5 weeks into flower and just before 5 weeks into flower, 3 of the 4 starting turning yellow. I know it's normal for this to happen but I feel this is too early. I don't have enough experience yet to know for sure if it's a deficiency or nute burn, etc. One thing I've noticed is that the 1 plant (purple punch) that has almost zero yellowing is always the first plant that I water.. Not sure if the order I'm watering in plays a part. I mix up my water thoroughly between each plant.

TENT- 4x4 tent with passive intake, a few oscillating clip fans inside, 2 levoit humidifiers inside to regulate vpd (using only distilled water in them), ac infinity exhaust and controller 67. cfm at 106 and tent size is 107 cubic feet.

SOIL- fox farms ocean forest in 7gal pots. I added some mychorrizol and a little extra Perlite.

FOOD- Feed every other watering using Fox farm nutrients using their feed chart using all their stuff, not just the trio. Also use cal-mag and hyrdrogaurd. Have been feeding around 1/2 the recommended amounts. Started nutrients 4 weeks after sprouting.

WATER- Mainly using filtered tap water that I let sit out for at least 24 hours. I have used distilled water as well. Have always ph'd to 6-6.5 and have done my best to keep EC at the proper levels based on ec charts I've found online. Normally around 1/2 the recommended nutrients gives me the correct EC levels.

PLANTS- Feminized Purple punch, mango kush, banana kush, Tropicana cookies.

LIGHT- Spider farmer upgraded se5000 (measured ppfd with apogee mq-610 par meter). Have the ppfd just under 1100 at the very top of canopy which is 13" above canopy at 100%. No added co2.

TEMP/HUMIDITY/VPD- Have maintained 79-82 during the day and 73-76 at night. I've had the VPD near perfect the entire grow so far.

GROW TECHNIQUE- For this grow I have followed nebulas Manifolding, plant training, and defoliation techniques as closely as possible.



Plants have looked fantastic until now aside from a little bit of what I think is nutrient burn. Any answers are very much appreciated!! Thank you so much.

[Going2fast]

Very nice looking crop. Congratulations. They look like they may need a little more nutes or maybe bump that pH up to 7. Ive had the same issue with autos. Could be lockout. Chemical nutes will raise the pH and the salts buildup isn't helping. Run some plain water at 7 ph thru them to get some runoff and see what it reads. If low flush them.

[Sdubus10]

Sorry, I forgot to mention they're all feminized, not autos. I always add my water, then nutes, mix really well, then check and adjust pH. After that I check ec/ppm. Readjust as needed. Then water.

So if I run plain ph'd water at 7 and they read lower than 7 in the runoff, I need to flush?

[Going2fast]

I saw that I was making a comparison. But yeah if it's 7 going in and 6 coming out I would flush them to get the pH back down. In my experience with liquid nutes they tend to build up fast.

[Sdubus10]

So if runoff pH is lower than going in, then I'm using too many nutrients and/or lots of salt buildup? What if runoff pH is higher than going in?

Sorry, I'm just a bit inexperienced in some areas. Thank you for understanding.

[OldManGrower]

My thoughts, such as they are:
I grow indoors in my own soil mix. I ph my water to ranger from 6.65 to 6.85. My runoff is always 6.5-6.6. I think your PH while in the correct range, needs to be higher.
Flush your plants with PH'd water and cal-mag. No nutes.
Cut back on the nutes to just the basics.
I do not know how much cal-mag you use, but you need to increase it.

Life cycle yellowing starts at the bottom and goes up. You definitely have a nutrient problem and need to "reset" your grow while there is still time. You have a nice grow going, good luck to you.

Also, your detailed information was very helpful.

[Sdubus10]

Thank you, I'm new to this but I'm sure you can tell I'm very detail oriented and research as much as possible! Still a lot to learn though!

That being said, if I'm in the correct pH range, what is the reason for increasing my pH a bit more?

Regarding the flush, should I also use the fox farm sledgehammer flush formula too or only ph'd water with calmag?

And yeah I've wondered that about calmag. I only use half the recommended dosage with fox farms stuff because full strength burnt my plants up my last grow. But I use a different brand calmag. I believe it's sensi calmag Xtra and I've been doing a lot less than recommended on that too. But I believe that's because it says to use like once a week and I use it every other water. So 2-3 times a week. Figured I should use less at a time since I'm using it more often than the directions.

Lastly, with it very likely being a nute problem, in your opinion do you think it's from too much or too little nutes?

Thank you so much!

[OldManGrower]

Cal-mag shouldn't burn plants. My girls get it from day one. I believe, from my own experience. that weed grown in soil appears to prefer a slightly more acidic environment. I would rather be closer to 7 than to six. I would not use the flush formula or any other junk. Too many chemicals. Nutes are vitamins for plants. Some vitamins pass through the body easily while others get stored up in the body until they become toxic. The same goes for nutes and plants. Every item that goes into your soil eventually builds up and becomes toxic. I am not advocating a strict organic routine, but rather the point that is less is more.

[Sdubus10]

That's all good to know! I really appreciate your help thus far!

When flushing like this would you recommend the same amount of water as I normally give (1 gallon per plant currently) or should I do like 2 gallons per plant for this flush?

Do you think I've likely been feeding them too many nutrients VS too little?

Thanks again!

Ps- after this grow I may look into other nutrients. I do feel like this is quite excessive.. (SEE Pic)

[Sdubus10]

[crucialbunny]

It's been my experience that some strains start giving up their sun leaves a bit sooner than others. For example; some years ago I grew some Super Glue plants and I had a similar situation as you are concerned with now. They harvested sooner than the other strains but still produced really nice potent buds. If your sugar leaves were yellowing then I might be concerned but I don't see that in your pics. If the leaves were browning or becoming splotchy it could be a nutrient issue but from what I can see they're just getting drained. I suppose it's possible that you have some lock-out going on but if that was the case I would expect to see it in the entire plant and not just sun leaves. Great looking grow and don't be surprised if they finish up sooner than you were expecting.

[Sdubus10]

Okay great, I was wondering that myself.. Meaning that they may finish a bit sooner than expected! I'll definitely be watching the trichomes early then just in case!

[bboyfromwayback]

If they turn yellow then fall off it’s lack of nitrogen. If they turn yellow and start to die off at the tips but still hang on (especially upper leaves) it’s likely a combination of ph and lights too intense