Nitrogen and Potassium Deficiency?

[Danielsaaan]

Hey all,

Problem: Yellowing leaves and leaf tips.

Medium: Fox Farms Ocean Forrest with additional Perlite.

Feed and Supplements: Fox Farm trio

Water source: Tap water pH to 6.0-6.5

Strain and Age: FastBuds Gelato - 44 days

Climate: 81 F, RH 40-50%. Tower fan for air circulation

Light: MarsHydro FCE4800

Additional Info: Today was the first time I included flower nutes with a feed. I fed 1/2 dose Grow Big, and normal doses of Big Bloom, Tiger Bloom, and Kelp, pH 6.2.

Picture:

I think I may be a little late incorporating flower nutrients, but will this help the problem? When should I notice improvement? Should I remove these leaves/not? Why? Appreciate any and all help!

Thank you,
Dan

 

[namvet25]

Plant looks good but try and add some calcium and clean out those bad leaves .

 

[tronN00dles]

Don’t feed 1/2 strength one element and full strength the others. You’re throwing off the NPK ratios has established with their feedchart. This leads to lockout. If you scale Grow Big, you need to scale Big Bloom and Tiger Bloom.

Rather than aiming for 1/2 strength, go by ppm/EC. Aim for an EC around 1.2 for autos then adjust as necessary. If you don’t have a TDS pen, has targets on their feedchart. Looking at the feedchart, I’m seeing mid bloom is around 2.5-3.0 EC, so you’re probably okay at half strength. But just keep that scaling factor consistent across all bottles.

tron

 

[Danielsaaan]

Don’t feed 1/2 strength one element and full strength the others. You’re throwing off the NPK ratios has established with their feedchart. This leads to lockout. If you scale Grow Big, you need to scale Big Bloom and Tiger Bloom.

Rather than aiming for 1/2 strength, go by ppm/EC. Aim for an EC around 1.2 for autos then adjust as necessary. If you don’t have a TDS pen, has targets on their feedchart. Looking at the feedchart, I’m seeing mid bloom is around 2.5-3.0 EC, so you’re probably okay at half strength. But just keep that scaling factor consistent across all bottles.

tron

Thanks tron! Will keep that in mind. Do you agree with the diagnosis I came up with though? I have an Apera pH pen, but that’s it
Much appreciated.

 

[tronN00dles]

Thanks tron! Will keep that in mind. Do you agree with the diagnosis I came up with though? I have an Apera pH pen, but that’s it
Much appreciated.

In my opinion, if you're using a reputable liquid nutrient line-up, it's counterproductive to chase individual "deficiencies". Any decent liquid trio specifically designed for cannabis should have all the nutrients you need. If you're seeing something that looks like a deficiency, chances are it's related to either pH, ppm/EC, or an imbalance of competing nutes, i.e., too much Ca-Mg relative to P-K can lock out P-K. In these cases, it's less an issue of a "deficiency" and rather an issue of malabsorption.

The correct course of action with a liquid trio line up is to follow the feedchart as per the manufacturer, and adjust your pH according to your medium (~6.5 for soil); and for autos in particular, dilute nutrients to 500-650ppm Hanna or 1.0-1.3 mS/cm (often refered to as 1.0 - 1.3 EC, or 1000-1200 uS/cm). This could be 1/2 strength with some lineups, 1/4 strength with others. If you don't have a TDS pen, look for these values on the feedchart and scale as necessary. So if a feedchart says Week 5 is 1.6EC, scale those nutes to 75% if you're targeting 1.2EC.

This article sums it up better than I can: https://www.autoflower.org/threads/a-word-on-nutrients.82004/

***Note - The above is the single most helpful thing I've found when it comes to liquid nutes with autos.

Back to your question, yeah yellowing from the bottom-up can be indicative of a nitrogen deficiency, but the solution isn't necessarily to "add more nitrogen". It's to ensure you're feeding balanced nutes at the proper ppm/EC and pH. You mention today was the first day you fed "flower nutes"- are you considering Big Bloom a flowering nute? Because according to the feedchart here: https://www.thegrowshow.org/fox-farm-feeding-schedule, Big Bloom should be fed from the start.

If I were a betting man, I'd think any 'deficiency' issue you're seeing is lockout-related from messing with the feedchart ratios and throwing your N-P-K-Ca-Mg ratios out of balance. Also, your plant is a smidge on the dark green side up top and those burnt edges indicate high ppm/EC's...

Having said all that, your plant still looks good. I wouldn't do anything drastic, but perhaps remove the depleted leaves from the bottom, give an extra plain pH'ed watering in between feeds, and then resume feeding as per the feedchart ratios, just diluted appropriately by ppm/EC as per the tutorial above.

Good luck!

tron

 

[Danielsaaan]

In my opinion, if you're using a reputable liquid nutrient line-up, it's counterproductive to chase individual "deficiencies". Any decent liquid trio specifically designed for cannabis should have all the nutrients you need. If you're seeing something that looks like a deficiency, chances are it's related to either pH, ppm/EC, or an imbalance of competing nutes, i.e., too much Ca-Mg relative to P-K can lock out P-K. In these cases, it's less an issue of a "deficiency" and rather an issue of malabsorption.

The correct course of action with a liquid trio line up is to follow the feedchart as per the manufacturer, and adjust your pH according to your medium (~6.5 for soil); and for autos in particular, dilute nutrients to 500-650ppm Hanna or 1.0-1.3 mS/cm (often refered to as 1.0 - 1.3 EC, or 1000-1200 uS/cm). This could be 1/2 strength with some lineups, 1/4 strength with others. If you don't have a TDS pen, look for these values on the feedchart and scale as necessary. So if a feedchart says Week 5 is 1.6EC, scale those nutes to 75% if you're targeting 1.2EC.

This article sums it up better than I can: https://www.autoflower.org/threads/a-word-on-nutrients.82004/

***Note - The above is the single most helpful thing I've found when it comes to liquid nutes with autos.

Back to your question, yeah yellowing from the bottom-up can be indicative of a nitrogen deficiency, but the solution isn't necessarily to "add more nitrogen". It's to ensure you're feeding balanced nutes at the proper ppm/EC and pH. You mention today was the first day you fed "flower nutes"- are you considering Big Bloom a flowering nute? Because according to the feedchart here: https://www.thegrowshow.org/fox-farm-feeding-schedule, Big Bloom should be fed from the start.

If I were a betting man, I'd think any 'deficiency' issue you're seeing is lockout-related from messing with the feedchart ratios and throwing your N-P-K-Ca-Mg ratios out of balance. Also, your plant is a smidge on the dark green side up top and those burnt edges indicate high ppm/EC's...

Having said all that, your plant still looks good. I wouldn't do anything drastic, but perhaps remove the depleted leaves from the bottom, give an extra plain pH'ed watering in between feeds, and then resume feeding as per the feedchart ratios, just diluted appropriately by ppm/EC as per the tutorial above.

Good luck!

tron

Thank you!